Evoluția spontană a pacienților cu hipotiroidism subclinic

Abstract

We aimed to analyse the natural course of subclinical hypothyroidism, quantify the incidence rate of overt hypothyroidism and evaluate the risk factors for the development of definitive thyroid failure. Thirty-five patients with subclinical hypothyroidism (29 women and 9 men) over age 30 yr. were prospectively studied. Subjects were followed up for 36 months with repeated determinations of TSH, FT4. Nine patients (25.71%) developed overt hypothyroidism, twelve patients (34.28%) showed normalization of their TSH values and 14 patients (40%) remained subclincal hypothyroid. Kaplan-Meier analysis showed that the development of definitive thyroid hypofunction was significantly related to the presence of symptoms of hypothyroidism, goiter, positive thyroid antibodies, and mainly low normal free T4 and high TSH concentrations at baseline. A stepwise multivariate Cox regression analyses showed that the only significant factor for progression to overt hypothyroidism was serum TSH concentration. In conclusion, serum TSH concentration is the most powerful predictor for the outcome of spontaneous subclinical hypothyroidism in patients over 30 years. Subjects with mildly elevated TSH have a low incidence rate of overt hypothyroidism. We recommend follow up with clinical and biochemical monitoring in these patients.