Two years follow-up study of eighty-eight patients with subclinical thyroid dysfunction

Objective To follow-up the patients with subclinical hypothyroidism and subclinical hyperthyroidism for 2 years and to analyse its natural course. Methods Questionaire was performed and sera was sampled in the population who took a physical examination in the clinic of endocrinology department of First Hospital of Peking University from September to December in 2002. Serum thyrotropin(TSH), thyroid hormone(TT4 and TT3), thyroid peroxidase antibody(TPOAb)were measured. Fifty-eight patients with subclinical hypothyroidism and 30 with subclinical hyperthyroidism were followed-up for study 2 years and the above parameters were reexamined. We eveluated the risk factors that affected the 2-year natural course of subclinical thyroid dysfunction. Results In the 58 patients with subclinical hypothyroidism 13(22.4%) returned to normal;44(75.9%)remained subclinically abnormal and 1(1.7%)progressed to clinical hypothyroidism.The palpable thyroid size and the concentration of serum TSH were the high-risk factors of progression to clinical hypothyroidism(P0.05 respectively). In 30 patients with subclinical hyperthyroidism, 22 patients(73.3%) returned to normal, 2(6.7%)remained subclinical abnormal, 1(3.3%)developed clinical hyperthyroidism and 5(16.7%) turned to subclinical hypothyroidism. The initial concentration of serum TSH affected the natural course of subclinical hyperthyroidism (P0.05). Conclusions Only a minor group of patients with subclinical thyroid dysfunction develop to clinical thyroid abnormalty in 2 years . Palpable thyroid size and high concentration of serum TSH(10 mIU/L)may predict the affect progression to clinical hypothyroidism, and the patients with serum TSH lower than 0.15 mIU/L may be a risk factor for progression to thyroid dysfunction.