The epidermis in thyroid disease*

Epidermal dimensions, replication and anabolic activity have been studied in thirteen patients with thyrotoxicosis and seven patients with hypothyroidism. Epidermal thickness and rete pattern were significantly reduced in hypothyroidism. The rates of epidermal cell division and anabolic activity in the epidermis were estimated by measuring the rates of incorporation of tritiated precursor compounds and were found to be increased in thyrotoxicosis. The mean autoradiographic labelling indices after the intracutaneous injection of tritiated thymidine were 9-1% in thyrotoxic patients and 4-3% in the hypothyroid group. None of the changes observed could be correlated accurately with the degree of thyroid gland activity, but increased thyroid activity was reflected in the epidermal changes better than decreased thyroid activity.