J Endocrinol Invest (2014) 37:25–29 DOI 10.1007/s40618-013-0008-y
ORIGINAL ARTICLE
Low prevalence of growth hormone deficiency in Turkish patients with Hashimoto’s thyroiditis ¨ . A. Gu¨rlek S. Akin • K. Aydin • O
Received: 14 June 2013 / Accepted: 17 November 2013 / Published online: 8 January 2014 Ó Italian Society of Endocrinology (SIE) 2013
Abstract Background Hashimoto’s Thyroiditis (HT) is frequently isolated, but may also be associated with other autoimmune disorders. Autoimmune hypophysitis can result in growth hormone deficiency (GHD). Various prevalences of GHD have been reported in HT in several different ethnic populations. Aim The aim of this study was assessing the prevalence of GHD in Turkish population with HT. Materials and methods Two hundred twenty-seven (208 females and 19 males, mean age 40.1 ± 10.8 years, range 18–64 years) patients with euthyroid HT were included. Results All patients were euthyroid with or without T4 treatment (median TSH 2.2 mIU/L, range 0.2–4.2 mIU/L; median FT4 15.6 pmol/L, range 12–22 pmol/L; and median FT3 4.5 pmol/L, range 3.0–6.2 pmol/L), and median TPO-Ab was 817 IU/mL (range 63 to [3,000). One hundred and thirty-six of them were using medications including L-thyroxine (59.9 %). Insulin-like growth factorI (IGF-I) levels of 210 patients (92.5 %) were normal. Glucagon stimulation testing in 17 subjects revealed GHD (peak \3 mcg/L) in two subjects. We then performed insulin tolerance test (ITT) to both of them as the gold standard confirmatory test. One patient had no GH response to ITT, either. Our data reveal the prevalence of GHD (based on low IGF-I and ITT result) in this particular group of Turkish HT patients as 0.4 %. Conclusion We conclude that the isolated GHD is rarely observed in HT in our population. The prevalence of GHD is 0.4 % in this particular group of Turkish HT patients ¨ . A. Gu¨rlek (&) S. Akin K. Aydin O Department of Endocrinology and Metabolism, Hacettepe University Medical School, Sıhhiye, Ankara, Turkey e-mail: [email protected]
suggesting that routine investigation of GHD is not mandatory. Keywords Growth hormone deficiency Prevalence Hashimoto’s thyroiditis Turkish Autoimmune hypophysitis
Introduction Hashimoto’s thyroiditis (HT) is the most common cause of hypothyroidism in areas of the world in which dietary iodine is sufficient. It is characterized by gradual thyroid failure due to autoimmune-mediated destruction of the thyroid gland. HT is frequently isolated but may be associated with other autoimmune disorders. Autoimmune (lymphocytic) hypophysitis can result in growth hormone deficiency (GHD) and is associated with other autoimmune endocrine diseases like HT or non-endocrine autoimmune diseases [1]. Growth hormone (GH) is the most abundant hormone in the adult pituitary gland, and it plays an important role in maintaining the metabolic process. Adult GHD is a recognized and treatable clinical entity. In adults, GHD is associated with adverse changes in body composition that include decreased lean muscle mass, muscle strength and increased body fat mass, lipid metabolism, insulin sensitivity, and exercise capacity [2–5]. There is also an association with a diminished quality of life. GHD can be caused by a variety of conditions. Adult GHD may be acquired or congenital. Of the acquired causes; pituitary tumors, extrapituitary tumors, pituitary surgery or irradiation, inflammatory or infiltrative disease of the hypothalamic-pituitary region, head trauma or vascular injury are encountered. In some cases, the cause of GHD
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is unknown. An uncommon cause is autoimmune hypophysitis. Autoimmune hypophysitis is characterized by a lymphocytic and plasma cell pituitary infiltrate that may be isolated or associated with other endocrinopathies. Circulating anti pituitary antibodies (APA) have occasionally been reported, and the presence of isolated pituitary hormone deficiency may imply an autoimmune process selectively targeted to pituitary cell types. Isolated or combined deficiencies of GH, LH/FSH, ACTH and TSH deficiency have been described so far [6, 7]. De Bellis et al. [8] and Manetti et al. [9] evaluated pituitary function in patients with HT and found isolated GHD in 5 %. Recently, Eskes et al. [1] reported that the prevalence of GHD in Dutch patients with autoimmune hypothyroidism is 0.4 % (two of 515). We aimed to investigate, for the first time, the prevalence of GHD in Turkish patients with HT.
Materials and methods Study population Two hundred twenty-seven (208 females and 19 males) consecutive patients with HT were evaluated in a crosssectional observational study. All patients have been followed at the Hacettepe Medical School, Department of Endocrinology and Metabolism which is a tertiary referral center in our country. Table 1 shows the clinical characteristics and biochemical parameters of the study population. Inclusion criteria were age from 18 to 65 year and HT [defined, besides an elevated TSH, as thyroid peroxidase antibody titer (TPO-Ab) C60 IU/mL (at present or ever documented in the past), and adequate T4 treatment (defined as serum TSH values from 0.2 to 4.2 mIU/L)]. Exclusion criteria were the following: (1) a history of
Table 1 Characteristics of study population Variable
Hashimoto’s thyroiditis (n = 227)
Age (years)
40.1 ± 10.8 (18–64)
Sex (M/F)
19 M/208 F
BMI (kg/m2) WHR
27.2 ± 4.9 (15.9–42.5) 0.8 ± 0.1 (0.4–2.0)
TSH (mIU/L)
2.1 ± 1.2 (0.2–4.2)
FT4 (pmol/L)
16.1 ± 2.8 (12–22)
FT3 (pmol/L)
4.6 ± 0.6 (3.0–6.2)
TPO-Ab (IU/mL)
Range 63 to [3000
IGF-1 (mcg/L)
166.7 ± 76.0 (46–614)
Data for continuous variables are presented as mean ± SD (ranges are in parentheses)
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hypothalamic or pituitary disease, (2) hypothyroidism after thyroid surgery or I131, (3) acute or chronic inflammatory disease, (4) pregnancy, (5) diabetes mellitus, (6) renal or hepatic disease, (7) cancer, (8) acute or chronic infections, (9) using any medication affecting thyroid function tests, (10) use of medications known to interfere with the GHIGF-I axis (e.g., corticosteroids), (11) Malnutrition. The study protocol was approved by the Ethics Committee of Hacettepe University School of Medicine. Written informed consent was obtained from all participants. Methods All subjects underwent a physical examination, detailed history and anthropometric measurements including body mass index (BMI) and waist-to-hip ratio (WHR). BMI was calculated by the Quetelet Formula (weight in kilograms divided by the square of height in meters). Waist circumference was measured from the narrowest point between the lowest rib and the uppermost lateral border of the iliac crest. The hip circumference was measured at their widest point. Samples of venous blood were taken in the morning after fasting overnight. Blood samples were stored at -80 °C until examination. Thyroid hormone levels, including TSH, free T4 (FT4) and free triiodothyronine (FT3), were measured by electrochemiluminescence immunoassay method (Roche Diagnostics GmbH). Normal values in our laboratory are as follows: TSH 0.2–4.2 mIU/L, FT4 12–22 pmol/L, and FT3 3.1–6.8 pmol/L. TPO-Ab was determined by chemiluminescence immunoassay (Immulite 2000, CA, USA). TPO-Ab levels of [35 IU/mL were considered positive. GH was measured via the chemiluminescence method (DPC, Immulite 2000, CA, USA); the lowest sensitivity level for the assay was 0.01 mcg/L. IGF-I was measured via two-site immunoradiometric assay (DSL-2800 ACTIVE, Diagnostic System Laboratories, Inc., Texas, USA); the lowest sensitivity level for the assay was 2.06 mcg/L. The reference values by age are given in Table 2. APA was evaluated in one patient in Germany (the assay is not routinely available in Turkey). It was assayed by indirect immunofluorescence (Euroimmun AG, Lu¨beck, Table 2 Reference values for plasma IGF-I concentrations (mcg/L) Age (years)
IGF-I (mcg/L) Min.
Max.
20–30
219
644
30–40
140
405
40–50
64
336
50–60 60–70
71 94
284 269
J Endocrinol Invest (2014) 37:25–29
Germany). APA test was considered positive starting at dilution 1/10.
27 Table 3 Laboratory characteristics of the IGF-1 levels below or at the age-specific reference values in the study IGF-1 levels below the age-specific reference values (n = 17)
Test procedures In patients with IGF-I levels below the according to agespecific reference values, a glucagon stimulation test was performed. On the test day, the subjects were fasting and were asked not to smoke or to perform exercise before test. All tests started between 8:30 and 09:00 h. An intravenous catheter was placed in the forearm for blood sampling. Basal blood samples were taken at 0 min. Then, glucagon (glucogen hypokit 1 mg, Novo Nordisk) was given as an intramuscular injection. Further samples were taken at 90, 120, 150, and 180 min. The subjects remained fasting, nonsmoking and sitting during the tests. GH was measured in all samples. GHD was defined as a GH peak after glucagon below the 3 mcg/L [10, 11]. When GHD was diagnosed with this test, further confirmation was done with an insulin tolerance test (ITT). Blood samples were taken at 0 min for measuring GH. After the blood sample at 0 min, 0.15 U/kg insulin (Actrapid; Novo Nordisk, Mainz, Germany) was iv administered. For ITT, patients received 0.15 IU/kg of regular insulin iv to achieve blood glucose levels below 40 mg/dl. Additional blood samples for measuring GH were taken at 15, 30, 45, 60, and 75 min. The response was considered impaired, if the GH peak was below the 3 mcg/L [12]. Statistical analysis Statistical analysis was performed by the Statistical Package for the Social Sciences (SPSS v.15.0). Data are expressed as mean ± Standard Deviation (SD). Normality of distribution was assesed by Kolmogorov–Smirnov test. Quantitative variables for two independent groups were compared by independent samples t test. Non-parametric variables were analyzed by Mann–Whitney U test. Associations between variables were examined by Pearson’s correlation coefficient. In all statistical analyses, p \ 0.05 was considered statistically significant.
Results In total, 208 female (91.6 %) and 19 male (8.4 %) patients were included in the study, mean age 40.1 ± 10.8 years (range 18–64 years). All participants had normal renal and hepatic function. Glucose homeostasis was normal. All patients were euthyroid with or without T4 treatment (median TSH 2.2 mIU/L, range 0.2–4.2 mIU/L; median FT4 15.6 pmol/L, range 12–22 pmol/L; and median FT3 4.5 pmol/L, range 3.0–6.2 pmol/L), and median TPO-Ab
TSH (lIU/mL)
1.84 (0.56–3.87)
FT4 (pmol/L)
14.90 (12.4–19.2)
FT3 (pmol/L)
4.58 (3.6–5.4)
IGF-1 levels at the age-specific reference values (n = 210) 2.23 (0.25–4.2) 15.68 (12–22)
p
NS NS
4.58 (3.0–6.29)
NS
Data are presented as median (ranges are in parentheses) NS Non-significant
was 817 IU/mL (range 63 to [3000). One hundred and thirty-six of them were using medications containing L-thyroxine (59.9 %). Insulin-like growth factor-I (IGF-I) levels of 210 patients (92.5 %) were normal. IGF-I was below the agespecific reference values in 17 of 227 subjects (7.5 %). We found also that serum IGF-I levels were similar in female patients (n = 208, 167.4 ± 78.4 mcg/L) and male patients (n = 19, 158.7 ± 42.1 mcg/L). There was no significant correlation between IGF-I levels and gender (r = -0.032, p = 0.632). BMI was 25.9 (range 15.9–36.8) kg/m2 and 26.7 (range 17.5–42.5) kg/m2 in subjects with an IGF-I levels below the age-specific reference values and at the age-specific reference values, respectively (p = 0.44). There were no significant differences in TSH, FT4, FT3, and TPO-Ab levels among IGF-I levels below or at the normal range for age in patients with HT (Table 3). Median GH and median IGF-I levels in patients with IGF-I levels below the age-specific reference values were 0.16 (range 0.05–2.64) mcg/L and 130 (range 46–207) mcg/L, respectively. We analyzed the correlations between IGF-I levels and BMI, TSH, FT4, FT3, and TPO-Ab parameters in the patients with IGF-I levels below the age-specific reference values. We found that there was no significant correlation between these parameters (p [ 0.05 for all). The glucagon stimulation test was done in the 17 patients with IGF-I below the age-specific reference values. Two of them had a GH peak below the 3 mcg/L. In one patient (27 year, female), we performed an additional ITT, and the GH peak during the ITT was above the 3 mcg/L, excluding GHD. In the other patient (38 year, female), the basal GH concentration was undetectable and did not rise after glucagon, whereas the GH peak during the ITT was 0.79 mcg/L, indicating to GHD. This patient had no other pituitary deficiencies, and a normal magnetic resonance imaging of the pituitary gland. This patient had no APA in her serum. The other 15 patients had a mean GH peak of 7.8 ± 5.2 mcg/L (range 3.0–19.5 mcg/L) during the glucagon stimulation test indicating to a normal GH reserve. All of the GH peaks occured between 120 and 180 min (100 %).
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Thus, the prevalence of GHD in this particular group of Turkish HT patients was calculated as 0.4 % (one out of 227).
Discussion Our study is the first report showing that GHD is 0.4 % in this particular group of Turkish HT patients. GHD represents one of the first abnormalities of the pituitary gland function. Stochholm et al. [13] reported that the morbidity of adults with GHD was approximately threefold higher than that of a healthy population. Some studies reported that prevalence of GHD is 5 % in patients with autoimmune thyroid diseases [8, 9]. However, Eskes et al. [1] demonstrated that a low prevalence of GHD is 0.4 % in patients with HT. Similarly, in the present study, we found that GHD is 0.4 %. Our patient had signs of GHD, such as her BMI was 35.9 kg/m2 and depressed mood. She was given GH replacement therapy. In our study, we did not routinely evaluated serum APA, because of the unavailability of this test in our country. Therefore, we could evaluate APA level only in the particular patient who had GHD by dynamic test. In this patient, APA level was negative (\1/10 titer). The clinical significance of APA in this situation is, however, still controversial. Whether APA represents an autoimmune marker of pituitary deficiency is a matter of discussion. De Bellis et al. [8] reported that low APA titers were associated with a normal pituitary function, whereas patients with high APA titers had severe GHD. Another study by Manetti et al. [9] investigated the functional significance of APA by assessing pituitary function in APA-positive patients. They found that of 110 APA-positive autoimmune thyroid disease patients, 102 were submitted to dynamic testing for functional pituitary assessment; 36 patients (35.2 %) had mild or severe GHD. In the novel study [1], patients were selected based on IGF-I levels for GHD. The authors did not evaluate serum APA level because of the sensitivity of it, for GHD is insufficient. Serum IGF-I is used as an indicator of GH status, even though it is well known that it is influenced by many factors and that a normal IGF-I cannot exclude GHD. Current guidelines recommend the evaluation of adult GHD to be based on clinical findings, medical history, and using the appropriate GH stimulation test for biochemical confirmation [14, 15], with the exception of patients with more pituitary hormone deficiencies and low serum IGF-I levels [16]. The ITT is generally considered the gold standard test for the evaluation of GHD [15–17]. Gomez et al. [10], Conceicao et al. [18], and Berg et al. [12] used glucagon stimulation test for assessing GHD in patients with pituitary disorders. In addition Manetti et al. [9] used a GHRH/
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arginine test, De Bellis et al. [8] used an ITT and an arginine test, and Eskes et al. [1] used GHRH/GH-releasing peptide-6 test for diagnosing GHD. We performed glucagon stimulation test in subjects with low levels of IGF-I. We preferred this test for screening for GHD because it is very convenient, easily applicable and acceptable by the patient. In addition, it does not carry the risk of significant hypoglycemia as occurs during ITT. The major limitation of the study is the selection of patients for dynamic tests according to age-related IGF-I levels. It is clearly known that in patients with GH deficiency, IGF-I could be within normal reference ranges. If all the patients were performed dynamic tests, GH prevalence might be higher. Accordingly, Yuen et al. [19] recommended the glucagon stimulation test as the alternative test to the ITT for diagnosing adult GHD based on its availability, reproducibility, safety, lack of influence by gender and hypothalamic cause of GHD. In summary, we demonstrate a very low prevalence of GHD in Turkish patients with HT. Our observations also suggest that patients with HT do not need a routine investigation for GHD and further investigations should be reserved for patients with clinical findings suggestive of GHD. These observations, however, must be confirmed by larger-scale, and in particular, population-based studies. ¨. Conflict of interest The authors S. Akin, K. Aydin, and O A. Gu¨rlek declare that they have no conflict of interest.
References 1. Eskes SA, Endert E, Fliers E, Wiersinga WM (2010) Prevalence of growth hormone deficiency in Hashimoto’s thyroiditis. J Clin Endocrinol Metab 95:2266–2270 2. de Boer H, Blok GJ, Van der Veen EA (1995) Clinical aspects of growth hormone deficiency in adults. Endocr Rev 16:63–86 3. Doga M, Bonadonna S, Gola M, Mazziotti G, Giustina A (2006) Growth hormone deficiency in the adult. Pituitary 9:305–311 4. Doga M, Bonadonna S, Gola M, Solerte SB, Amato G, Carella C, Giustina A (2005) Current guidelines for adult GH replacement. Rev Endocr Metab Disord 6:63–70 5. Gola M, Bonadonna S, Doga M, Giustina A (2005) Clinical review: growth hormone and cardiovascular risk factors. J Clin Endocrinol Metab 90:1864–1870 6. Caturegli P, Newschaffer C, Olivi A, Pomper MG, Burger PC, Rose NR (2005) Autoimmune hypophysitis. Endocr Rev 26:599–614 7. De Bellis A, Ruocco G, Battaglia M, Conte M, Coronella C, Tirelli G, Bellastella A, Pane E, Sinisi AA, Bizzarro A, Bellastella G (2008) Immunological and clinical aspects of lymphocytic hypophysitis. Clin Sci (Lond) 114:413–421 8. De Bellis A, Bizzarro A, Conte M, Perrino S, Coronella C, Solimeno S, Sinisi AM, Stile LA, Pisano G, Bellastella A (2003) Antipituitary antibodies in adults with apparently idiopathic growth hormone deficiency and in adults with autoimmune endocrine diseases. J Clin Endocrinol Metab 88:650–654 9. Manetti L, Lupi I, Morselli LL, Albertini S, Cosottini M, Grasso L, Genovesi M, Pinna G, Mariotti S, Bogazzi F, Bartalena L,
J Endocrinol Invest (2014) 37:25–29
10.
11.
12.
13.
14.
Martino E (2007) Prevalence and functional significance of antipituitary antibodies in patients with autoimmune and nonautoimmune thyroid diseases. J Clin Endocrinol Metab 92:2176–2181 Gomez JM, Espadero RM, Escobar-Jimenez F, Hawkins F, Pico A, Herrera-Pombo JL, Vilardell E, Duran A, Mesa J, Faure E, Sanmarti A (2002) Growth hormone release after glucagon as a reliable test of growth hormone assessment in adults. Clin Endocrinol (Oxf) 56:329–334 Carmichael JD, Danoff A, Milani D, Roubenoff R, Lesser ML, Livote E, Reitz RE, Ferris S, Kleinberg DL (2006) GH peak response to GHRH-arginine: relationship to insulin resistance and other cardiovascular risk factors in a population of adults aged 50–90. Clin Endocrinol (Oxf) 65:169–177 Berg C, Meinel T, Lahner H, Yuece A, Mann K, Petersenn S (2010) Diagnostic utility of the glucagon stimulation test in comparison to the insulin tolerance test in patients following pituitary surgery. Eur J Endocrinol 162:477–482 Stochholm K, Laursen T, Green A, Laurberg P, Andersen M, Kristensen LO, Feldt-Rasmussen U, Christiansen JS, Frydenberg M, Gravholt CH (2008) Morbidity and GH deficiency: a nationwide study. Eur J Endocrinol 158:447–457 Molitch ME, Clemmons DR, Malozowski S, Merriam GR, Shalet SM, Vance ML, Stephens PA (2006) Evaluation and treatment of
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15.
16.
17.
18.
19.
adult growth hormone deficiency: an Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab 91:1621–1634 Molitch ME, Clemmons DR, Malozowski S, Merriam GR, Vance ML (2011) Evaluation and treatment of adult growth hormone deficiency: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab 96:1587–1609 Hartman ML, Crowe BJ, Biller BM, Ho KK, Clemmons DR, Chipman JJ (2002) Which patients do not require a GH stimulation test for the diagnosis of adult GH deficiency? J Clin Endocrinol Metab 87:477–485 Cook DM, Yuen KC, Biller BM, Kemp SF, Vance ML (2009) American Association of Clinical Endocrinologists medical guidelines for clinical practice for growth hormone use in growth hormone-deficient adults and transition patients-2009 update: executive summary of recommendations. Endocr Pract 15:580–586 Conceicao FL, da Costa e Silva A, Leal Costa AJ, Vaisman M (2003) Glucagon stimulation test for the diagnosis of GH deficiency in adults. J Endocrinol Invest 26:1065–1070 Yuen KC, Biller BM, Molitch ME, Cook DM (2009) Clinical review: 1s lack of recombinant growth hormone (GH)-releasing hormone in the United States a setback or time to consider glucagon testing for adult GH deficiency? J Clin Endocrinol Metab 94:2702–2707
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ORIGINAL ARTICLE
Low prevalence of growth hormone deficiency in Turkish patients with Hashimoto’s thyroiditis ¨ . A. Gu¨rlek S. Akin • K. Aydin • O
Received: 14 June 2013 / Accepted: 17 November 2013 / Published online: 8 January 2014 Ó Italian Society of Endocrinology (SIE) 2013
Abstract Background Hashimoto’s Thyroiditis (HT) is frequently isolated, but may also be associated with other autoimmune disorders. Autoimmune hypophysitis can result in growth hormone deficiency (GHD). Various prevalences of GHD have been reported in HT in several different ethnic populations. Aim The aim of this study was assessing the prevalence of GHD in Turkish population with HT. Materials and methods Two hundred twenty-seven (208 females and 19 males, mean age 40.1 ± 10.8 years, range 18–64 years) patients with euthyroid HT were included. Results All patients were euthyroid with or without T4 treatment (median TSH 2.2 mIU/L, range 0.2–4.2 mIU/L; median FT4 15.6 pmol/L, range 12–22 pmol/L; and median FT3 4.5 pmol/L, range 3.0–6.2 pmol/L), and median TPO-Ab was 817 IU/mL (range 63 to [3,000). One hundred and thirty-six of them were using medications including L-thyroxine (59.9 %). Insulin-like growth factorI (IGF-I) levels of 210 patients (92.5 %) were normal. Glucagon stimulation testing in 17 subjects revealed GHD (peak \3 mcg/L) in two subjects. We then performed insulin tolerance test (ITT) to both of them as the gold standard confirmatory test. One patient had no GH response to ITT, either. Our data reveal the prevalence of GHD (based on low IGF-I and ITT result) in this particular group of Turkish HT patients as 0.4 %. Conclusion We conclude that the isolated GHD is rarely observed in HT in our population. The prevalence of GHD is 0.4 % in this particular group of Turkish HT patients ¨ . A. Gu¨rlek (&) S. Akin K. Aydin O Department of Endocrinology and Metabolism, Hacettepe University Medical School, Sıhhiye, Ankara, Turkey e-mail: [email protected]
suggesting that routine investigation of GHD is not mandatory. Keywords Growth hormone deficiency Prevalence Hashimoto’s thyroiditis Turkish Autoimmune hypophysitis
Introduction Hashimoto’s thyroiditis (HT) is the most common cause of hypothyroidism in areas of the world in which dietary iodine is sufficient. It is characterized by gradual thyroid failure due to autoimmune-mediated destruction of the thyroid gland. HT is frequently isolated but may be associated with other autoimmune disorders. Autoimmune (lymphocytic) hypophysitis can result in growth hormone deficiency (GHD) and is associated with other autoimmune endocrine diseases like HT or non-endocrine autoimmune diseases [1]. Growth hormone (GH) is the most abundant hormone in the adult pituitary gland, and it plays an important role in maintaining the metabolic process. Adult GHD is a recognized and treatable clinical entity. In adults, GHD is associated with adverse changes in body composition that include decreased lean muscle mass, muscle strength and increased body fat mass, lipid metabolism, insulin sensitivity, and exercise capacity [2–5]. There is also an association with a diminished quality of life. GHD can be caused by a variety of conditions. Adult GHD may be acquired or congenital. Of the acquired causes; pituitary tumors, extrapituitary tumors, pituitary surgery or irradiation, inflammatory or infiltrative disease of the hypothalamic-pituitary region, head trauma or vascular injury are encountered. In some cases, the cause of GHD
123
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J Endocrinol Invest (2014) 37:25–29
is unknown. An uncommon cause is autoimmune hypophysitis. Autoimmune hypophysitis is characterized by a lymphocytic and plasma cell pituitary infiltrate that may be isolated or associated with other endocrinopathies. Circulating anti pituitary antibodies (APA) have occasionally been reported, and the presence of isolated pituitary hormone deficiency may imply an autoimmune process selectively targeted to pituitary cell types. Isolated or combined deficiencies of GH, LH/FSH, ACTH and TSH deficiency have been described so far [6, 7]. De Bellis et al. [8] and Manetti et al. [9] evaluated pituitary function in patients with HT and found isolated GHD in 5 %. Recently, Eskes et al. [1] reported that the prevalence of GHD in Dutch patients with autoimmune hypothyroidism is 0.4 % (two of 515). We aimed to investigate, for the first time, the prevalence of GHD in Turkish patients with HT.
Materials and methods Study population Two hundred twenty-seven (208 females and 19 males) consecutive patients with HT were evaluated in a crosssectional observational study. All patients have been followed at the Hacettepe Medical School, Department of Endocrinology and Metabolism which is a tertiary referral center in our country. Table 1 shows the clinical characteristics and biochemical parameters of the study population. Inclusion criteria were age from 18 to 65 year and HT [defined, besides an elevated TSH, as thyroid peroxidase antibody titer (TPO-Ab) C60 IU/mL (at present or ever documented in the past), and adequate T4 treatment (defined as serum TSH values from 0.2 to 4.2 mIU/L)]. Exclusion criteria were the following: (1) a history of
Table 1 Characteristics of study population Variable
Hashimoto’s thyroiditis (n = 227)
Age (years)
40.1 ± 10.8 (18–64)
Sex (M/F)
19 M/208 F
BMI (kg/m2) WHR
27.2 ± 4.9 (15.9–42.5) 0.8 ± 0.1 (0.4–2.0)
TSH (mIU/L)
2.1 ± 1.2 (0.2–4.2)
FT4 (pmol/L)
16.1 ± 2.8 (12–22)
FT3 (pmol/L)
4.6 ± 0.6 (3.0–6.2)
TPO-Ab (IU/mL)
Range 63 to [3000
IGF-1 (mcg/L)
166.7 ± 76.0 (46–614)
Data for continuous variables are presented as mean ± SD (ranges are in parentheses)
123
hypothalamic or pituitary disease, (2) hypothyroidism after thyroid surgery or I131, (3) acute or chronic inflammatory disease, (4) pregnancy, (5) diabetes mellitus, (6) renal or hepatic disease, (7) cancer, (8) acute or chronic infections, (9) using any medication affecting thyroid function tests, (10) use of medications known to interfere with the GHIGF-I axis (e.g., corticosteroids), (11) Malnutrition. The study protocol was approved by the Ethics Committee of Hacettepe University School of Medicine. Written informed consent was obtained from all participants. Methods All subjects underwent a physical examination, detailed history and anthropometric measurements including body mass index (BMI) and waist-to-hip ratio (WHR). BMI was calculated by the Quetelet Formula (weight in kilograms divided by the square of height in meters). Waist circumference was measured from the narrowest point between the lowest rib and the uppermost lateral border of the iliac crest. The hip circumference was measured at their widest point. Samples of venous blood were taken in the morning after fasting overnight. Blood samples were stored at -80 °C until examination. Thyroid hormone levels, including TSH, free T4 (FT4) and free triiodothyronine (FT3), were measured by electrochemiluminescence immunoassay method (Roche Diagnostics GmbH). Normal values in our laboratory are as follows: TSH 0.2–4.2 mIU/L, FT4 12–22 pmol/L, and FT3 3.1–6.8 pmol/L. TPO-Ab was determined by chemiluminescence immunoassay (Immulite 2000, CA, USA). TPO-Ab levels of [35 IU/mL were considered positive. GH was measured via the chemiluminescence method (DPC, Immulite 2000, CA, USA); the lowest sensitivity level for the assay was 0.01 mcg/L. IGF-I was measured via two-site immunoradiometric assay (DSL-2800 ACTIVE, Diagnostic System Laboratories, Inc., Texas, USA); the lowest sensitivity level for the assay was 2.06 mcg/L. The reference values by age are given in Table 2. APA was evaluated in one patient in Germany (the assay is not routinely available in Turkey). It was assayed by indirect immunofluorescence (Euroimmun AG, Lu¨beck, Table 2 Reference values for plasma IGF-I concentrations (mcg/L) Age (years)
IGF-I (mcg/L) Min.
Max.
20–30
219
644
30–40
140
405
40–50
64
336
50–60 60–70
71 94
284 269
J Endocrinol Invest (2014) 37:25–29
Germany). APA test was considered positive starting at dilution 1/10.
27 Table 3 Laboratory characteristics of the IGF-1 levels below or at the age-specific reference values in the study IGF-1 levels below the age-specific reference values (n = 17)
Test procedures In patients with IGF-I levels below the according to agespecific reference values, a glucagon stimulation test was performed. On the test day, the subjects were fasting and were asked not to smoke or to perform exercise before test. All tests started between 8:30 and 09:00 h. An intravenous catheter was placed in the forearm for blood sampling. Basal blood samples were taken at 0 min. Then, glucagon (glucogen hypokit 1 mg, Novo Nordisk) was given as an intramuscular injection. Further samples were taken at 90, 120, 150, and 180 min. The subjects remained fasting, nonsmoking and sitting during the tests. GH was measured in all samples. GHD was defined as a GH peak after glucagon below the 3 mcg/L [10, 11]. When GHD was diagnosed with this test, further confirmation was done with an insulin tolerance test (ITT). Blood samples were taken at 0 min for measuring GH. After the blood sample at 0 min, 0.15 U/kg insulin (Actrapid; Novo Nordisk, Mainz, Germany) was iv administered. For ITT, patients received 0.15 IU/kg of regular insulin iv to achieve blood glucose levels below 40 mg/dl. Additional blood samples for measuring GH were taken at 15, 30, 45, 60, and 75 min. The response was considered impaired, if the GH peak was below the 3 mcg/L [12]. Statistical analysis Statistical analysis was performed by the Statistical Package for the Social Sciences (SPSS v.15.0). Data are expressed as mean ± Standard Deviation (SD). Normality of distribution was assesed by Kolmogorov–Smirnov test. Quantitative variables for two independent groups were compared by independent samples t test. Non-parametric variables were analyzed by Mann–Whitney U test. Associations between variables were examined by Pearson’s correlation coefficient. In all statistical analyses, p \ 0.05 was considered statistically significant.
Results In total, 208 female (91.6 %) and 19 male (8.4 %) patients were included in the study, mean age 40.1 ± 10.8 years (range 18–64 years). All participants had normal renal and hepatic function. Glucose homeostasis was normal. All patients were euthyroid with or without T4 treatment (median TSH 2.2 mIU/L, range 0.2–4.2 mIU/L; median FT4 15.6 pmol/L, range 12–22 pmol/L; and median FT3 4.5 pmol/L, range 3.0–6.2 pmol/L), and median TPO-Ab
TSH (lIU/mL)
1.84 (0.56–3.87)
FT4 (pmol/L)
14.90 (12.4–19.2)
FT3 (pmol/L)
4.58 (3.6–5.4)
IGF-1 levels at the age-specific reference values (n = 210) 2.23 (0.25–4.2) 15.68 (12–22)
p
NS NS
4.58 (3.0–6.29)
NS
Data are presented as median (ranges are in parentheses) NS Non-significant
was 817 IU/mL (range 63 to [3000). One hundred and thirty-six of them were using medications containing L-thyroxine (59.9 %). Insulin-like growth factor-I (IGF-I) levels of 210 patients (92.5 %) were normal. IGF-I was below the agespecific reference values in 17 of 227 subjects (7.5 %). We found also that serum IGF-I levels were similar in female patients (n = 208, 167.4 ± 78.4 mcg/L) and male patients (n = 19, 158.7 ± 42.1 mcg/L). There was no significant correlation between IGF-I levels and gender (r = -0.032, p = 0.632). BMI was 25.9 (range 15.9–36.8) kg/m2 and 26.7 (range 17.5–42.5) kg/m2 in subjects with an IGF-I levels below the age-specific reference values and at the age-specific reference values, respectively (p = 0.44). There were no significant differences in TSH, FT4, FT3, and TPO-Ab levels among IGF-I levels below or at the normal range for age in patients with HT (Table 3). Median GH and median IGF-I levels in patients with IGF-I levels below the age-specific reference values were 0.16 (range 0.05–2.64) mcg/L and 130 (range 46–207) mcg/L, respectively. We analyzed the correlations between IGF-I levels and BMI, TSH, FT4, FT3, and TPO-Ab parameters in the patients with IGF-I levels below the age-specific reference values. We found that there was no significant correlation between these parameters (p [ 0.05 for all). The glucagon stimulation test was done in the 17 patients with IGF-I below the age-specific reference values. Two of them had a GH peak below the 3 mcg/L. In one patient (27 year, female), we performed an additional ITT, and the GH peak during the ITT was above the 3 mcg/L, excluding GHD. In the other patient (38 year, female), the basal GH concentration was undetectable and did not rise after glucagon, whereas the GH peak during the ITT was 0.79 mcg/L, indicating to GHD. This patient had no other pituitary deficiencies, and a normal magnetic resonance imaging of the pituitary gland. This patient had no APA in her serum. The other 15 patients had a mean GH peak of 7.8 ± 5.2 mcg/L (range 3.0–19.5 mcg/L) during the glucagon stimulation test indicating to a normal GH reserve. All of the GH peaks occured between 120 and 180 min (100 %).
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Thus, the prevalence of GHD in this particular group of Turkish HT patients was calculated as 0.4 % (one out of 227).
Discussion Our study is the first report showing that GHD is 0.4 % in this particular group of Turkish HT patients. GHD represents one of the first abnormalities of the pituitary gland function. Stochholm et al. [13] reported that the morbidity of adults with GHD was approximately threefold higher than that of a healthy population. Some studies reported that prevalence of GHD is 5 % in patients with autoimmune thyroid diseases [8, 9]. However, Eskes et al. [1] demonstrated that a low prevalence of GHD is 0.4 % in patients with HT. Similarly, in the present study, we found that GHD is 0.4 %. Our patient had signs of GHD, such as her BMI was 35.9 kg/m2 and depressed mood. She was given GH replacement therapy. In our study, we did not routinely evaluated serum APA, because of the unavailability of this test in our country. Therefore, we could evaluate APA level only in the particular patient who had GHD by dynamic test. In this patient, APA level was negative (\1/10 titer). The clinical significance of APA in this situation is, however, still controversial. Whether APA represents an autoimmune marker of pituitary deficiency is a matter of discussion. De Bellis et al. [8] reported that low APA titers were associated with a normal pituitary function, whereas patients with high APA titers had severe GHD. Another study by Manetti et al. [9] investigated the functional significance of APA by assessing pituitary function in APA-positive patients. They found that of 110 APA-positive autoimmune thyroid disease patients, 102 were submitted to dynamic testing for functional pituitary assessment; 36 patients (35.2 %) had mild or severe GHD. In the novel study [1], patients were selected based on IGF-I levels for GHD. The authors did not evaluate serum APA level because of the sensitivity of it, for GHD is insufficient. Serum IGF-I is used as an indicator of GH status, even though it is well known that it is influenced by many factors and that a normal IGF-I cannot exclude GHD. Current guidelines recommend the evaluation of adult GHD to be based on clinical findings, medical history, and using the appropriate GH stimulation test for biochemical confirmation [14, 15], with the exception of patients with more pituitary hormone deficiencies and low serum IGF-I levels [16]. The ITT is generally considered the gold standard test for the evaluation of GHD [15–17]. Gomez et al. [10], Conceicao et al. [18], and Berg et al. [12] used glucagon stimulation test for assessing GHD in patients with pituitary disorders. In addition Manetti et al. [9] used a GHRH/
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arginine test, De Bellis et al. [8] used an ITT and an arginine test, and Eskes et al. [1] used GHRH/GH-releasing peptide-6 test for diagnosing GHD. We performed glucagon stimulation test in subjects with low levels of IGF-I. We preferred this test for screening for GHD because it is very convenient, easily applicable and acceptable by the patient. In addition, it does not carry the risk of significant hypoglycemia as occurs during ITT. The major limitation of the study is the selection of patients for dynamic tests according to age-related IGF-I levels. It is clearly known that in patients with GH deficiency, IGF-I could be within normal reference ranges. If all the patients were performed dynamic tests, GH prevalence might be higher. Accordingly, Yuen et al. [19] recommended the glucagon stimulation test as the alternative test to the ITT for diagnosing adult GHD based on its availability, reproducibility, safety, lack of influence by gender and hypothalamic cause of GHD. In summary, we demonstrate a very low prevalence of GHD in Turkish patients with HT. Our observations also suggest that patients with HT do not need a routine investigation for GHD and further investigations should be reserved for patients with clinical findings suggestive of GHD. These observations, however, must be confirmed by larger-scale, and in particular, population-based studies. ¨. Conflict of interest The authors S. Akin, K. Aydin, and O A. Gu¨rlek declare that they have no conflict of interest.
References 1. Eskes SA, Endert E, Fliers E, Wiersinga WM (2010) Prevalence of growth hormone deficiency in Hashimoto’s thyroiditis. J Clin Endocrinol Metab 95:2266–2270 2. de Boer H, Blok GJ, Van der Veen EA (1995) Clinical aspects of growth hormone deficiency in adults. Endocr Rev 16:63–86 3. Doga M, Bonadonna S, Gola M, Mazziotti G, Giustina A (2006) Growth hormone deficiency in the adult. Pituitary 9:305–311 4. Doga M, Bonadonna S, Gola M, Solerte SB, Amato G, Carella C, Giustina A (2005) Current guidelines for adult GH replacement. Rev Endocr Metab Disord 6:63–70 5. Gola M, Bonadonna S, Doga M, Giustina A (2005) Clinical review: growth hormone and cardiovascular risk factors. J Clin Endocrinol Metab 90:1864–1870 6. Caturegli P, Newschaffer C, Olivi A, Pomper MG, Burger PC, Rose NR (2005) Autoimmune hypophysitis. Endocr Rev 26:599–614 7. De Bellis A, Ruocco G, Battaglia M, Conte M, Coronella C, Tirelli G, Bellastella A, Pane E, Sinisi AA, Bizzarro A, Bellastella G (2008) Immunological and clinical aspects of lymphocytic hypophysitis. Clin Sci (Lond) 114:413–421 8. De Bellis A, Bizzarro A, Conte M, Perrino S, Coronella C, Solimeno S, Sinisi AM, Stile LA, Pisano G, Bellastella A (2003) Antipituitary antibodies in adults with apparently idiopathic growth hormone deficiency and in adults with autoimmune endocrine diseases. J Clin Endocrinol Metab 88:650–654 9. Manetti L, Lupi I, Morselli LL, Albertini S, Cosottini M, Grasso L, Genovesi M, Pinna G, Mariotti S, Bogazzi F, Bartalena L,
J Endocrinol Invest (2014) 37:25–29
10.
11.
12.
13.
14.
Martino E (2007) Prevalence and functional significance of antipituitary antibodies in patients with autoimmune and nonautoimmune thyroid diseases. J Clin Endocrinol Metab 92:2176–2181 Gomez JM, Espadero RM, Escobar-Jimenez F, Hawkins F, Pico A, Herrera-Pombo JL, Vilardell E, Duran A, Mesa J, Faure E, Sanmarti A (2002) Growth hormone release after glucagon as a reliable test of growth hormone assessment in adults. Clin Endocrinol (Oxf) 56:329–334 Carmichael JD, Danoff A, Milani D, Roubenoff R, Lesser ML, Livote E, Reitz RE, Ferris S, Kleinberg DL (2006) GH peak response to GHRH-arginine: relationship to insulin resistance and other cardiovascular risk factors in a population of adults aged 50–90. Clin Endocrinol (Oxf) 65:169–177 Berg C, Meinel T, Lahner H, Yuece A, Mann K, Petersenn S (2010) Diagnostic utility of the glucagon stimulation test in comparison to the insulin tolerance test in patients following pituitary surgery. Eur J Endocrinol 162:477–482 Stochholm K, Laursen T, Green A, Laurberg P, Andersen M, Kristensen LO, Feldt-Rasmussen U, Christiansen JS, Frydenberg M, Gravholt CH (2008) Morbidity and GH deficiency: a nationwide study. Eur J Endocrinol 158:447–457 Molitch ME, Clemmons DR, Malozowski S, Merriam GR, Shalet SM, Vance ML, Stephens PA (2006) Evaluation and treatment of
29
15.
16.
17.
18.
19.
adult growth hormone deficiency: an Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab 91:1621–1634 Molitch ME, Clemmons DR, Malozowski S, Merriam GR, Vance ML (2011) Evaluation and treatment of adult growth hormone deficiency: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab 96:1587–1609 Hartman ML, Crowe BJ, Biller BM, Ho KK, Clemmons DR, Chipman JJ (2002) Which patients do not require a GH stimulation test for the diagnosis of adult GH deficiency? J Clin Endocrinol Metab 87:477–485 Cook DM, Yuen KC, Biller BM, Kemp SF, Vance ML (2009) American Association of Clinical Endocrinologists medical guidelines for clinical practice for growth hormone use in growth hormone-deficient adults and transition patients-2009 update: executive summary of recommendations. Endocr Pract 15:580–586 Conceicao FL, da Costa e Silva A, Leal Costa AJ, Vaisman M (2003) Glucagon stimulation test for the diagnosis of GH deficiency in adults. J Endocrinol Invest 26:1065–1070 Yuen KC, Biller BM, Molitch ME, Cook DM (2009) Clinical review: 1s lack of recombinant growth hormone (GH)-releasing hormone in the United States a setback or time to consider glucagon testing for adult GH deficiency? J Clin Endocrinol Metab 94:2702–2707
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