ANALYSIS OF FACTORS IN HYPERTHYROIDISM, WHICH DETERMINE THE DURATION OF SUPPRESSIVE TREATMENT BEFORE RECOVERY OF THYROID STIMULATING HORMONE SECRETION

Abstract

SUMMARY In twenty‐three thyrotoxic patients a prospective study was undertaken to assess the time until restoration of TSH secretion. For several methodological reasons we chose to study a model in which the patients were deliberately continued on full dose treatment until biochemical hypothyroidism was established. The period until reappearance of TSH secretion varied between 42 and 293 days. In this time FTI had become subnormal, while T3 and the clinical index remained in the normal range. The interval until TSH restoration was not correlated with the parameters of thyroid status from the initial evaluation with the exception of a negative correlation with log PB131I 48 h (r= 0·511; P < 0·02). The average follow up period in our patients was 115 days during which FTI decreased exponentially to 19±7 ± 20±5. The disappearance of T3 followed a biphasic course in which after 2–4 weeks T3 decline practically ceased and concentrations remained normal. Assuming that a FTI between 100 and 65 was the threshold value beneath which hypophyseal TSH synthesis and secretion could be expected, we were able to determine the interval between the corresponding date and the date of returning TSH secretion in twenty‐one patients. This latency time was 34 ± 9±7 days and proved completely independent of the total time until TSH reappearance. In contrast there was a highly significant correlation (r= 0·987; P<0·001) between the time to reach the assumed threshold level and the time to recovery of TSH secretion. The disappearance of FTI, although widely variable from patient to patient, showed a constant rate throughout the full scale from elevated to practically absent concentrations. Thus, the initial part of the disappearance curve determines the length of time until restoration of TSH secretion. This is illustrated by the tight relationship (r= 0·92; P < 0·001) between FTI after 28 days of treatment and the time when TSH started to rise. Knowledge of the FTI on day 28 allows treatment to be tailored to the needs of the individual patient.

The Time to Thyroid-Stimulating Hormone Recovery During Medical Treatment in Graves’ Disease and Autonomous Hyperthyroidism

“…In both studied groups we did not observe significant correlations between the time to TSH recovery and the parameters of thyroid function from the pretreatment evaluation, findings supported in GD patients by Fischer et al (36). Yet, in GD patients, after controlling for the mean dose of ATDs/ day TTR was longer in patients with higher FT3, TT3 at diagnosis and higher TT3 at the first visit after ATDs administration.…”

“…All patients were further divided by the time to TSH recovery in 5 subgroups: <3, 3-6, 6-9, 9-12 and >12 months from the diagnosis. In the GD group the cumulative recovery rates of serum TSH were: 36 (Fig. 2).…”

Impaired local deiodination of thyroxine to triiodothyronine in dogs with symmetrical truncal alopecia

“…This is of interest since this is the type of deiodinase that is most prevalent in human skin (Kaplan et al, 1988) and since this type of enzyme is supposed to be of regulatory importance in maintaining the normal active thyroid hormone (i.e. T3) levels in various species and organs (Fischer et aL, 1982;Lum et aL, 1984;Silva and Matthews, 1984;Rudas, 1989).…”

Central Hypothyroidism in Children

“…The outcome of CCH babies of mothers with gestational hyperthyroidism recalls the hyporesponsiveness of the pituitary TSH in adult patients with hyperthyroidism: after the start of antithyroid medication T 4 normalizes quickly, but the recovery of TSH secretion (both basal and in response to TRH) is rather slow, taking weeks or months [110,111].…”