title: Potential pitfalls of the 2-hour calcium-to-creatinine ratio and urinary cyclic adenosine monophosphate excretion in the differential diagnosis of idiopathic hypercalciuria.
abstract: We studied 44 patients with calcium urolithiasis on high (900 mg. daily) and low (400 mg. daily) calcium diets. With 24-hour urinary data, we categorized the patients as normocalciuric or hypercalciuric and subdivided the hypercalciuric patients into absorptive and renal types. Abbreviated tests, including the 2-hour fasting urinary calcium-to-creatinine ratio and 24-hour urinary (nephrogenous) cyclic adenosine monophosphate, did not predict accurately whether hypercalciuria was of the idiopathic, absorptive or renal type. However, 24-hour urinary calcium excretions on the low calcium diet had a sensitivity and specificity of more than 90 per cent for reproducing the categorized diagnoses.
mesh_terms: D002118:Calcium / Q000378:metabolism / Q000652:urine*; D002136:Calcium, Dietary / Q000008:administration & dosage; D003404:Creatinine / Q000652:urine*; D000242:Cyclic AMP / Q000652:urine*; D006801:Humans; D007408:Intestinal Absorption; D007668:Kidney / Q000503:physiopathology; D007677:Kidney Function Tests; D014545:Urinary Calculi / Q000209:etiology / Q000503:physiopathology / Q000652:urine*
chemical_list: D002136:Calcium, Dietary; D003404:Creatinine; D000242:Cyclic AMP; D002118:Calcium