Forearm muscle metabolism in primary hypothyroidism.

Thyrotoxicosis is associated with increased skeletal muscle glucose metabolism and lipid oxidation in the fasted state. Conversely, in hypothyroidism, glucose metabolism is reduced. The present study has assessed in patients the effects of chronic thyroid hormone deficiency, on insulin-stimulated skeletal muscle metabolism, using a combination of the forearm and hyperinsulinaemic euglycaemic clamp techniques. Seven female patients presenting with primary auto-immune hypothyroidism were studied at presentation and 4-9 months after being rendered biochemically euthyroid. No significant differences were demonstrated between the hypothyroid and euthyroid states in forearm muscle blood flow, or in glucose or lipid metabolism.