Incidence of different forms of thyroid dysfunction and its degrees in an iodine sufficient area.

Abstract

Study objective: The aim of the study was to determine the incidence of thyroid dysfunction in an iodine sufficient area (Vigo city, Galicia, North-West of Spain).

Design: Case-finding study during a 3-year (1990-1992) period.

Subjects: Subjects from a random sample of the population with abnormal results on FT4, sensitive-TSH or antithyroid autoantibodies.

Measurements: Thyroid size by ultrasound study. FT4 by RIA; TSA Ab by radio receptor assays; TSH, Tg Ab and TMS Ab by IRMA.

Major results: Overall incidence of thyroid dysfunction was 97.96 per 100,000 per year (CI 95% 78.86-117.06); female 162.45, male 17.44. Incidence rate of hyperthyroidism was 52.37 per 100,000 per year (CI 95% 38.41-66.36); 24.24 for Graves' disease, 11.63 for nodular hyperthyroidism, 13.57 for iatrogenic hyperthyroidism and 2.90 for others causes. Incidence rate of hypothyroidism was 45.58 per 100,000 per year (CI 95% 32.55-58.620 27.15 for hypothyroid autoimmune thyroiditis, 8.72 for postoperative hypothyroidism, 4.89 for miscellaneous hypothyroidism, 1.93 for amiodarone induced hypothyroidism and 2.90 for secondary hypothyroidism.

Conclusions: This investigation provides extensive data on incidence of clinical and subclinical thyroid dysfunction and its different forms in an iodine sufficient area.