Na-K-dependent ATPase in red cells and thyroid status.

Abstract

The Relationship between ouabain-sensitive ATPase (Na-K ATPase) activity in erythrocytes and the thyroid status was studied in 36 patients with Graves' disease ren served as control. Clinically euthyroid children treated with L-T4 were divided into 2 groups with regard to Na-K ATPase activity, normal and low. Analysis of the possible factors peared to be the endogenous T4 level, while in patients with dwarfism, the secretory capacity of TSH or TSH-releasing hormone (TRH) was contributory. Thus Na-K ATPase activity in red cells remains within the normal range after L-T4 replacement in the presence of a severe degree of primary hypothyroidism or in association with secondary or tertiary hypothyroidism.Other factors such as the L-T4 dose, duration of the therapy, serum T4 and T3 concentrations, were not significantly different in the two groups. These results indicate that (1) Na-K ATPase in red cells is decreased in hyper-or hypothyroid state, (2) restoration of normal activity requires 1-3 months of euthyroid period, and (3) it is a sensitive index of peripheral thyroid status over the preceding few months.