August 1975
LETTERS T O T H E EDITOR
279
Biochemical Abnormalities in Hypothyroidism
Received December 3, 1974; accepted for publication February 3, 1975. Key words: Hypothyroidism; Serum enzymes; Serum chemistry. Address reprint requests to Dr. Pain: Division of Clinical Chemistry, Institute of Medical and Veterinary Science, Box 14, Rundle St. P. O., Adelaide, South Australia 5000.
285:529-533, 1971 3. Nicoloff J T , Low JC, Dussault J H , et al: Simultaneous measurement of thyroxine and triiodothyronine peripheral turnover kinetics in man. J Clin Invest 51:473-483, 1972 4. Surks MI, Schadlow AR, Stock JM, et al: Determination of iodothyronine absorption and conversion of L-thyroxine (T4) to L-triiodothyronine (T3) using turnover rate techniques. J Clin Invest 52:805-811, 1973
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To the Editor: — In a recent informative thyroid extract, and 50 fig. of triiodothyroarticle, 1 Chertow and coauthors draw at- nine) were excessive. Full replacement in tention to significant elevations of serum the great majority of hypothyroid patients concentrations of CPK, LDH and SGOT is achieved with 0.10-0.20 mg. of thythat may occur in untreated hypothyroid- roxine. 2 Corresponding amounts of thyroid ism and which may be rectified by replace- extract and triiodothyronine are 6 0 - 1 2 0 ment therapy. They also point out that mg. and 2 0 - 4 0 fig., respectively (triiodoeven normal pretreatment concentrations thyronine is four times as metabolically of these same enzymes plus those of al- active as thyroxine, the production rate of bumin, total protein, and creatinine may triiodothyronine is 18-42 fig. per day, 3 decrease significantly following replace- and the extent of absorption of thyroxine ment. In addition to the rational mecha- by the gut is only 4 0 - 7 0 % , whereas that nisms for these changes advanced by the of triiodothyronine is virtually 100%4). authors, I would like to add the possi- Therefore, obviously some and probably bility of decreased catabolism of the most of the subjects studied by Chertow enzymes in hypothyroidism. It would be of and associates were in fact mildly hyperthyinterest to learn whether the authors noted roid due to overreplacement. Thus, while any changes in sodium and glucose con- the changes reported are real, some (e.g., centrations in these subjects, since hypo- those in proteins and creatinine) may in natremia due to water retention or sodium fact be exaggerated by overreplacement. s e q u e s t r a t i o n into p s e u d o m u c i n o u s In passing, I was surprised to see the material and hyperglycemia due to insulin abbreviations "gm %" and "mg %" used in resistance are well recognized conse- Figure 1, rather than the more acceptable quences of hypothryoidism. "g/100 ml" and "mg/100 ml." T h e observations recorded are of ROY W. PAIN, M.B., B.S., F.R.C.P.A. definite clinical importance, for should a Division of Clinical Chemistry hypothyroid patient be given replacement Institute of Medical and Veterinary Science therapy and subsequently experience chest Adelaide, South Australia pain, raised enzyme concentrations might then be misinterpreted as being due to References myocardial infarction resulting from too1. Chertow BS, Motto GS, Shah J H : A biochemical rapid replacement therapy. profile of abnormalities in hypothyroidism. My main purpose in writing, however, is Am J Clin Pathol 61:785-788, 1974 2. Cotton GE, Gorman CA, Mayberry WE: Suppresto point out that the daily replacement sion of thyrotrophin(h-TSH) in serums of dosages given to the patients studied (0.2patients with myxedema of varying etiology 0.3 mg. of thyroxine, 120-240 mg. of treated with thyroid hormones. N Engl J Med
LETTERS T O T H E EDITOR
279
Biochemical Abnormalities in Hypothyroidism
Received December 3, 1974; accepted for publication February 3, 1975. Key words: Hypothyroidism; Serum enzymes; Serum chemistry. Address reprint requests to Dr. Pain: Division of Clinical Chemistry, Institute of Medical and Veterinary Science, Box 14, Rundle St. P. O., Adelaide, South Australia 5000.
285:529-533, 1971 3. Nicoloff J T , Low JC, Dussault J H , et al: Simultaneous measurement of thyroxine and triiodothyronine peripheral turnover kinetics in man. J Clin Invest 51:473-483, 1972 4. Surks MI, Schadlow AR, Stock JM, et al: Determination of iodothyronine absorption and conversion of L-thyroxine (T4) to L-triiodothyronine (T3) using turnover rate techniques. J Clin Invest 52:805-811, 1973
Downloaded from http://ajcp.oxfordjournals.org/ by guest on June 5, 2016
To the Editor: — In a recent informative thyroid extract, and 50 fig. of triiodothyroarticle, 1 Chertow and coauthors draw at- nine) were excessive. Full replacement in tention to significant elevations of serum the great majority of hypothyroid patients concentrations of CPK, LDH and SGOT is achieved with 0.10-0.20 mg. of thythat may occur in untreated hypothyroid- roxine. 2 Corresponding amounts of thyroid ism and which may be rectified by replace- extract and triiodothyronine are 6 0 - 1 2 0 ment therapy. They also point out that mg. and 2 0 - 4 0 fig., respectively (triiodoeven normal pretreatment concentrations thyronine is four times as metabolically of these same enzymes plus those of al- active as thyroxine, the production rate of bumin, total protein, and creatinine may triiodothyronine is 18-42 fig. per day, 3 decrease significantly following replace- and the extent of absorption of thyroxine ment. In addition to the rational mecha- by the gut is only 4 0 - 7 0 % , whereas that nisms for these changes advanced by the of triiodothyronine is virtually 100%4). authors, I would like to add the possi- Therefore, obviously some and probably bility of decreased catabolism of the most of the subjects studied by Chertow enzymes in hypothyroidism. It would be of and associates were in fact mildly hyperthyinterest to learn whether the authors noted roid due to overreplacement. Thus, while any changes in sodium and glucose con- the changes reported are real, some (e.g., centrations in these subjects, since hypo- those in proteins and creatinine) may in natremia due to water retention or sodium fact be exaggerated by overreplacement. s e q u e s t r a t i o n into p s e u d o m u c i n o u s In passing, I was surprised to see the material and hyperglycemia due to insulin abbreviations "gm %" and "mg %" used in resistance are well recognized conse- Figure 1, rather than the more acceptable quences of hypothryoidism. "g/100 ml" and "mg/100 ml." T h e observations recorded are of ROY W. PAIN, M.B., B.S., F.R.C.P.A. definite clinical importance, for should a Division of Clinical Chemistry hypothyroid patient be given replacement Institute of Medical and Veterinary Science therapy and subsequently experience chest Adelaide, South Australia pain, raised enzyme concentrations might then be misinterpreted as being due to References myocardial infarction resulting from too1. Chertow BS, Motto GS, Shah J H : A biochemical rapid replacement therapy. profile of abnormalities in hypothyroidism. My main purpose in writing, however, is Am J Clin Pathol 61:785-788, 1974 2. Cotton GE, Gorman CA, Mayberry WE: Suppresto point out that the daily replacement sion of thyrotrophin(h-TSH) in serums of dosages given to the patients studied (0.2patients with myxedema of varying etiology 0.3 mg. of thyroxine, 120-240 mg. of treated with thyroid hormones. N Engl J Med
