A DOUBLE‐BLIND CROSS‐OVER 12‐MONTH STUDY OF l‐THYROXINE TREATMENT OF WOMEN WITH ‘SUBCLINICAL’ HYPOTHYROIDISM

Abstract

Twenty women, who had been randomly selected from women with subclinical hypothyroidism identified in a population study were treated with L-thyroxine and placebo in a double-blind cross-over design during 2 x 6 months. Three women did not complete the study, one because she moved to another part of the country, and two because of nervousness and sense of tachycardia. None of these 'drop-outs' had any objective signs of overtreatment; they had normal pulse rate and a serum T3 concentration within the reference interval. During L-thyroxine treatment serum procollagen-III-peptide concentration increased in 13 women out of the 17 women completing the study and at the end of treatment the mean concentration was significantly raised (P less than 0.001). Serum concentrations of procollagen-III-peptide then correlated with those of free thyroxine (P less than 0.01), total thyroxine (P less than 0.05), and reverse triiodothyronine (P less than 0.05). The same comparison revealed little or no effect on the concentrations of serum creatine kinase activity, transcortin or sex-hormone binding globulin. Heart rate-corrected preejection period and symptom score decreased (P less than 0.05). Four women starting with L-thyroxine showed a marked and prolonged (4-6 months) rise in thyrotrophin concentration during the subsequent placebo period, but remained clinically euthyroid. Four women (of 17) improved during therapy as judged by psychometric testing and their own rating. We could not by pretreatment observations identify these four women apart from serum free and total 3,5,3'-triiodothyronine concentrations in the lower part of the health-associated reference interval. Subclinical hypothyroidism is common among middle-aged and old women, and our findings indicate that approximately one woman in four with this 'subclinical' condition will benefit from L-thyroxine treatment.

Are neuropsychological changes relevant in subclinical hypothyroidism?

“…Because age may cause alterations in the cognitive function (13), we selected patients aged from 18 to 65 years, thereby avoiding the insertion of confounding factors, since the incidence of neuropsychological changes is higher outside that age group. Thus, our study differs from others (15,16), in which the patients were older than 65 years.…”

“…However, Jorde et al (18), using a battery of tests in a population study to assess attention, visual and verbal memory, intelligence and executive functions, found no difference between patients with SH and euthyroid individuals. Four studies (12,(15)(16)(17) reported an improvement in the performance of tests assessing the neuropsychological function of patients with SH when treated with thyroid hormones; nevertheless, one (18) found no significant change.…”

Multi-center study on the prevalence of hypothyroidism in patients with hypercholesterolemia

“…The male: female ratios were 5:4 in Ab-positive and 4:7 in Ab-negative hypothyroid patients, respectively. There were no statistically significant differences in BMI and in TSH values between Ab-positive (BMI 25.5 kg/m 2 and TSH 18.1 mU/L) and Ab-negative (27.0 kg/m 2 and ies done with double-blind placebo controlled, TC and LDL-C but not HDL-C improved in the four studies [29][30][31][32] but unchanged in the remaining four studies [33][34][35][36]. We are currently following up the patients with overt and subclinical hypothyroidism treated by T4 replacement to elucidate its effects on the lipid profile.…”

Variation in thyroid function in subclinical hypothyroidism: importance of clinical follow-up and therapy

“…Randomised clinical trials on HYPO-related symptoms and signs in patients with SCH have shown contradictory effects of L-T 4 replacement therapy (27,(47)(48)(49)(50)(51)(52)(53). As a consequence of the variation in results of thyroid function test in patients with SCH, diagnoses may shift between euthyroidism, SCH and HYPO.…”