Urinary Excretion of Cyclic AMP and Cyclic GMP in Primary Hyperparathyroidism with Reference to Clinical Signs and Symptoms

Abstract

35 patients with surgically proven primary hyperparathyroidism (PHPT) were evaluated with regard to urinary cyclic AMP and cyclic GMP excretion. They showed no signs of bone disease or impaired renal function. Preoperatively, cyclic AMP was increased in 28 patients (80%). Mean excretory value for the whole group was 8.5 ± 0.8 micromoles/g creat/24 hours, compared with controls, 4.2 ± 0.13 micromoles/g creat/24 hours. Cyclic AMP excretion was normalized after surgery.

Urinary cyclic GMP was increased in 14 patients (40%) compared with excretion rates of controls, 0.46 ± 0.03 micromoles/g creat/24 hours. Cyclic GMP increments persisted postoperatively, although at a lower level. There was an apparent lack of effect of one nucleotide on the other.

Clinical, pathological and biochemical data were analyzed and correlated for significant associations. The patients demonstrating augmented cyclic GMP excretion rates were not distinguishable from those with normal cyclic GMP production rates with regard to S-calcium, U-calcium, U-cyclic AMP, S-phosphate, cholelithiasis, nephrolithiasis, hypertension or age.

One of twelve patients meeting the criteria of normocalcemic PHPT had increased excretion of cyclic AMP and was submitted to parathyroid surgery. Microscopy showed four normal glands. Our data indicate that the increased excretion of cyclic GMP in urine was not a metabolic effect of the parathyroid hormone, since increments were noted also after resection of the parathyroids. Furthermore, it is not likely that the cyclic GMP increments reflected an increased secretion of calcitonin, since these increments were noted during hypercalcemia as well as normocalcemia. The source and cause of production of the cyclic GMP remain to be determined.

Key words

Primary Hyperparathyroidism - Cyclic AMP - Cyclic GMP