Influence of the thyroid on exocrine pancreatic function.

Exocrine pancreatic function was studied in 15 patients with hypothyroidism and 15 healthy subjects by means of the amino acid consumption test, a new tubeless test based on the measurement of plasma amino acid uptake by the pancreas during pancreatic enzyme synthesis stimulation. Nine of the 15 patients were also studied after they had become euthyroid following thyroxine treatment. Pancreatic function was significantly reduced in patients with hypothyroidism compared with healthy subjects. Treatment with thyroxine restored pancreatic function to normal. In two additional hypothyroid patients studied by means of duodenal intubation, pancreatic secretion of both bicarbonate and enzymes was found to be significantly decreased. It was concluded that the thyroid gland plays an essential role in maintaining the functional integrity of the exocrine pancreas in humans.