Metabolic Responses to Acute and Chronicl-Dopa Administration in Patients with Parkinsonism

Abstract

The metabolic effects of L-dopa were studied in 23 patients with Parkinsonism. Levels of plasma growth hormone were elevated two hours after administration of 0.5 to 1.0 g of L-dopa, and this response persisted for at least one year. Plasma glucose was increased at two hours, and free fatty acids at four hours. Chronic therapy significantly increased serum cholesterol (approximately 10 per cent), but no change in serum triglycerides, thyroxine, fasting blood sugar, and 24-hour urinary excretion of 17-keto and 17-ketogenic steroids was observed. After one year of chronic L-dopa therapy, there was a decrease in glucose tolerance associated with a delayed and exaggerated insulin response. The changes in growth hormone and carbohydrate tolerance suggest that patients receiving L-dopa for long periods should be monitored for the possible development of frank acromegaly.