141 " IS " T4 TOXICOSIS A NORMAL BIOCHEMICAL FINDING IN ELDERLY WOMEN?
VALERIE QUINN K. E. BRITTON A. C. D. CAYLEY SHEILA M. ELLIS B. L. BROWN J. M. MIRALLES R. P. EKINS Department of Nuclear Medicine, Middlesex Hospital Medical School, London W1N 7RL
The lack of equivalence in the distribution of normal ranges for free thyroxine index (FT4I) and free triiodothyronine index (FT3I) in the over sixty-five age-group, as compared with the fifteen-sixty-five age-group, supports the idea that " T4 toxicosis " is a common biochemical finding in elderly women. The disparity between FT4I and FT3I ranges was also reflected in the true free T4 and free T3 levels which were measured in some cases. These results suggest that when an increased FT4I is found in an elderly woman with cardiac disease, caution should be exercised in interpreting the result as indicating that thyrotoxicosis is the cause of the cardiac disorder. Estimation of total T3, FT3I, or free T3 seems useful in confirming euthyroidism in such cases. Sum ary
binding globulin 3 Total T3 is determined by saturation analysisand free T3 index by dividing this measurement by that of the thyopac-3. True dialysed free T4 and free T3 are determined by saturation analysis.$.6 In this laboratory the stated normal ranges are as follows: total T4 45-115 ng. per m1.2; total T3 and FT31 600-1800 pg. per ml.; free T4 21-40 pg. per ml.5; free T3 3-9-7-4 New normal ranges for free T4 (7-5-17) pg. per ml.5 and free T3 (3-5-6-5 pg. per ml.) are attributable to a change in technique.6 1569 consecutive request forms were evaluated and the FT4i ranges defined for the group in which the clinical
diagnosis was " probable euthyroidism," " possible hypothyroidism," or " possible hyperthyroidism," excluding all those patients on thyroid-related therapy, after thyroid surgery, 1311 therapy, on oral contraceptives, with pituitary disorders, or who were pregnant. This reduced the numbers from 1569 to 1443. These samples were drawn from typical hospital patients. Results in the age-groups zero-fifteen years, fifteen-sixty-five years, and sixty-five TABLE
I-FT4I
AND
FT3I
VALUES BY AGE-GROUP
Introduction IN
a study of thyroid strategy 1 in which the conof cept decision-aiding ranges was put forward as an alternative to normal ranges, we re-evaluated our normal ranges for serum triiodothyronine (T3) and free thyroxine (T4) index.
TABLE II-MEAN AGE :f:S.D. AND RATIO OF FEMALES/MALES IN PATIENTS ACCORDING TO FT3I AND FT4I MEASUREMENTS
Methods The free T4 index (FT4I) is determined in this laboratory by dividing the total serum-thyroxine (T4), determined by saturation analysis,2by theThyopac-3’ value, which represents the available binding sites on thyroxineTABLE III--CLINICAL DETAILS IN PATIENTS OVER 60 WITH FT4I VALUES OVER 130
A.P. =Alkaline phosphatase, King-Armstrong units. Bil. = Bilirubin (mg./lOO ml.). c.c.p. = Congestive cardiac failure. L.v. + = Left ventricular impulse prominent and displaced.
ng./ml.
AND NORMAL
FT31
VALUES
N = Normal. P.T.H. *
=
Parathyroid.
Sinus rhythm. = Old technique.’
S.R.
=
335 ,
142 years and over were
considered in 335 patients in whom were measured.
both free T4 and T3 indices
Results
The distributions of values of FT4I and FT3I in two age-groups are shown in table i. The differences in mean FT4I and in mean FT3I between the two agefor the females. The groups were significant (P
VALERIE QUINN K. E. BRITTON A. C. D. CAYLEY SHEILA M. ELLIS B. L. BROWN J. M. MIRALLES R. P. EKINS Department of Nuclear Medicine, Middlesex Hospital Medical School, London W1N 7RL
The lack of equivalence in the distribution of normal ranges for free thyroxine index (FT4I) and free triiodothyronine index (FT3I) in the over sixty-five age-group, as compared with the fifteen-sixty-five age-group, supports the idea that " T4 toxicosis " is a common biochemical finding in elderly women. The disparity between FT4I and FT3I ranges was also reflected in the true free T4 and free T3 levels which were measured in some cases. These results suggest that when an increased FT4I is found in an elderly woman with cardiac disease, caution should be exercised in interpreting the result as indicating that thyrotoxicosis is the cause of the cardiac disorder. Estimation of total T3, FT3I, or free T3 seems useful in confirming euthyroidism in such cases. Sum ary
binding globulin 3 Total T3 is determined by saturation analysisand free T3 index by dividing this measurement by that of the thyopac-3. True dialysed free T4 and free T3 are determined by saturation analysis.$.6 In this laboratory the stated normal ranges are as follows: total T4 45-115 ng. per m1.2; total T3 and FT31 600-1800 pg. per ml.; free T4 21-40 pg. per ml.5; free T3 3-9-7-4 New normal ranges for free T4 (7-5-17) pg. per ml.5 and free T3 (3-5-6-5 pg. per ml.) are attributable to a change in technique.6 1569 consecutive request forms were evaluated and the FT4i ranges defined for the group in which the clinical
diagnosis was " probable euthyroidism," " possible hypothyroidism," or " possible hyperthyroidism," excluding all those patients on thyroid-related therapy, after thyroid surgery, 1311 therapy, on oral contraceptives, with pituitary disorders, or who were pregnant. This reduced the numbers from 1569 to 1443. These samples were drawn from typical hospital patients. Results in the age-groups zero-fifteen years, fifteen-sixty-five years, and sixty-five TABLE
I-FT4I
AND
FT3I
VALUES BY AGE-GROUP
Introduction IN
a study of thyroid strategy 1 in which the conof cept decision-aiding ranges was put forward as an alternative to normal ranges, we re-evaluated our normal ranges for serum triiodothyronine (T3) and free thyroxine (T4) index.
TABLE II-MEAN AGE :f:S.D. AND RATIO OF FEMALES/MALES IN PATIENTS ACCORDING TO FT3I AND FT4I MEASUREMENTS
Methods The free T4 index (FT4I) is determined in this laboratory by dividing the total serum-thyroxine (T4), determined by saturation analysis,2by theThyopac-3’ value, which represents the available binding sites on thyroxineTABLE III--CLINICAL DETAILS IN PATIENTS OVER 60 WITH FT4I VALUES OVER 130
A.P. =Alkaline phosphatase, King-Armstrong units. Bil. = Bilirubin (mg./lOO ml.). c.c.p. = Congestive cardiac failure. L.v. + = Left ventricular impulse prominent and displaced.
ng./ml.
AND NORMAL
FT31
VALUES
N = Normal. P.T.H. *
=
Parathyroid.
Sinus rhythm. = Old technique.’
S.R.
=
335 ,
142 years and over were
considered in 335 patients in whom were measured.
both free T4 and T3 indices
Results
The distributions of values of FT4I and FT3I in two age-groups are shown in table i. The differences in mean FT4I and in mean FT3I between the two agefor the females. The groups were significant (P
