[Early prediction of hypothyroidism after subtotal thyroidectomy (author's transl)]

30 patients were classified euthyroid (group A, n = 13) and hypothyroid (group B, n = 17) 4 years after subtotal thyroidectomy. A retrospective analysis of the hormonal status was then performed. In both groups (A and B) a significant decrease of serum T3 was found 3 days after surgery. 3 months later T3 levels had returned to normal. Serum T4 showed no significant change, neither at day 3 nor 3 months after the operation. Serum thyrotropin (TSH) also showed no significant change 3 days after surgery in both groups. However, 3 months later serum TSH levels were found to be significantly increased in group B (greater than 4.8 microU/ml, Mean = 13.0 +/- 6.7 microU/ml, p less than 0.001) while in group A TSH remained normal (normal range: 0--3.4 microU/ml). Assuming a serum TSH of 5.0 microU/ml as critical level at 3 months after subtotal thyroidectomy 25% of eventually hypothyroid patients will be missed and 1% will be classified hypothyroid. It is therefore suggested that all patients with serum TSH of more than 4.8 microU/ml 3 months after surgery should be considered chronically hypothyroid. The patients with a serum TSH between 3.4--4.8 microU/ml should be kept on prophylactic thyroid hormone therapy until further 3 months later the final diagnosis is established.