Plasma and urinary amino acids as indicators of proximal tubular function in primary hyperparathyroidism

Nineteen patients with histologically confirmed parathyroid adenomas were studied immediately before and 12 months after operation. The concentrations of 37 amino acids were estimated by chromatography in plasma and urine. In addition, proximal tubular function was studied by measuring the excretion of beta 2-microglobulin. No general aminoaciduria was registered either before or after operation but there were variations between preoperative and postoperative values in the plasma and urinary concentrations of a few amino acids. There were no correlations between preoperative and postoperative concentrations of calcium, parathyroid hormone or the various amino acids in plasma or urine. Nor was there any between the fall in serum calcium and the concentrations of the amino acids. There was no correlation between glomerular filtration rate and the amount of the different amino acids filtered. beta 2-Microglobulin excretion was normal both before and after operation in all but one patient. Aminoaciduria does not seem to be present in primary hyper-parathyroidism. Plasma and urinary concentrations of amino acids were unchanged after parathyroidectomy and proximal tubular function, assessed by measuring concentrations of amino acids in plasma and urine and urinary excretion of beta 2-microglobulin does not seem to be affected in primary hyperparathyroidism.