The 24-h urinary cyclic adenosine 3', 5' monophosphate/creatinine ratio: an useful approach to the diagnosis of parathyroid disorders and function.

24-h urinary cyclic adenosine 3', 5'-monophosphate/creatinine (cAMP/Cr) ratio was assessed in 10 patients with hypoparathyroidism, 6 with primary hyperparathyroidism, 7 with normocalcemic hypercalciuria and recurrent nephrolithiasis, 14 with osteomalacia, 25 with Paget's disease and 53 with symptomatic postmenopausal osteoporosis. In hypoparathyroid subjects the mean values of 24 h cAMP/Cr ratio were significantly lower than the control values, whereas in patients with parathyroid adenoma the mean values were higher and fell after parathyroid surgery. Patients with nephrolithiasis due to absorptive hypercalciuria showed low or normal cAMP/Cr ratio, whereas in those with osteomalacia and mean values of cAMP/Cr ratio were significantly higher than the control values and decreased after vitamin D treatment. The mean value of the 24 h urine cAMP/Cr ratio was normal in patients with Paget's disease or postmenopausal osteoporosis and increased significantly after long term treatment with calcitonin or diphosphonate. This increase paralleled a significant decrease of calcium plasma level. A significant improvement of fractional calcium absorption was observed in women with postmenopausal osteoporosis at the end of treatment with calcitonin or diphosphonate.