Urinary excretion of cyclic AMP in primary hyperparathyroidism

[Evaluation of renal cyclic adenosine monophosphate, serum parathyroid hormone and phosphate reabsorption in recurrent calcium urolithiasis, healthy controls and hyperparathyroidism (author's transl)]

In three groups (n = 12 each) of male controls (22--43 years), patients with recurring calcium urolithiasis (21--36 years) and hyperparathyroidism (HPT; 17--71 years) proven by surgery renal cyclic adenosine monophosphate (RcAMP), fractional tubular phosphate reabsorption and serum parathyroid hormone (PTH) were measured during endogenous creatinine clearance. RcAMP (muMol/g creatinine) was: controls 1.48 +/- SEM 0.27; stone formers 2.037 +/- 0.343 (not significantly different); HPT 6.234 +/- 0.454 (p less than 0.001). There is no overlap between HPT and controls. Phosphate reabsorption is least in HPT (0.84 +/- 0.015), higher in controls (0.924 +/- 0.004) and stone formers (0.941 +/- 0.007). All differences are statistically significant. Under the conditions selected (moderate hydration of individuals) Serum PHT (pg-equiv/ml) is lowest in stome formers (less than 100--339), higher in controls (less than 100--933) and HPT (400--1150). there is no overlap in PHT between the former and the latter group but a marked one between controls and HPT. For clinical purposes the resulting diagnostic uncertainty in a given patient can be overcome by additional determinations of RcAMP and ionised serum calcium: when referring to serum PTH HPT patients fall outside, RCU patients within 2 standard deviations of either parameter in control subjects. This procedure presently appears superior to those proposed in the past (urinary cAMP etc.) but requires confirmation in larger patient populations. Moreover, since HPT prevails in middle and upper age decades, their RcAMP values and those of RCU patients should be related to a range seen in closely age- and sex-matched controls.

Urinary cyclic AMP in diagnosis and management of hypercalcaemia: studies of patients without primary hyperparathyroidism

Urinary adenosine -3' ,5' - cyclic monophosphate was measured in 14 patients with hypercalcaemia not caused by primary hyperparathyroidism. Increased levels were found in patients with malignant disease without bone metastases and believed to be examples of paraendocrine syndrome. Decreased levels were found in patients with metastatic carcinoma involving bone, and in patients with multiple myeloma, lymphoma and immobilisation after fracture. Results obtained during treatment for hypercalaemia are described in three patients. In two hypercalcaemic patients (one with hyperthyroidism and one with breast cancer with bone metastases) normal levels were found. This measurement is a useful substitute for assay of serum parathyroid hormone and is of value in the diagnosis of hypercalcaemia, in monitoring effects of treatment and in revealing underlying mechanisms.