Correlation between thyroxine, triiodothyronine and thyrotropin in geriatric patients with goitre.

Serum TSH, T4 and T3 have been assayed in three groups of older persons (greater than 60 years): in 28 normal subjects (A), in 80 patients with nontoxic goitre (B), in 22 patients with hyperthyroidism (C). Group B was divided in group B-1 (TSH 0.20-0.30 mU/l) and group B-2 (TSH greater than 0.30 mU/l). The test characteristics were determined by comparison of group C patients with group A patients and the former with group B patients. The specificity and posterior probability of TSH test calculated by the first comparison was 1.0 for both characteristics, and by the second comparison TSH test specificity was 0.75 and posterior probability 0.62. Specificity of thyroid hormones calculated in the second comparison was 0.96 for T4-test and 0.94 for T3-test. Therefore TSH test is the most adequate in clinical diagnostic of thyrotoxic goiter. The particularities of several groups were: B-2 group had significantly lower mean value of T4 than Group A, but there was no significant difference between mean values of TSH found. There were no correlations between TSH and T4 and between T4 and T3. Group B-1 had significantly lower mean TSH value than Group A and Group B, but the groups did not differ in mean T4 value. The correlation between TSH and T4 in group was positive as the correlation between T4 and T3. It is suggested that the value of serum T4 of Group B-1 may be inappropriately low due to defective immunological activity of T4 from autonomous follicles.(ABSTRACT TRUNCATED AT 250 WORDS)