title: Idiopathic hypercalciuria with bilateral macular colobomata: a new variant of oculo-renal syndrome.
abstract: Two siblings from a consanguineous family, suffering from nephrocalcinosis and nephrolithiasis caused by idiopathic hypercalciuria are described. The condition is associated with bilateral macular colobomata and tapeto-retinal degeneration. It is known that the latter can occur together with different nephropathies; however, until now it has never been described in combination with idiopathic hypercalciuria. Blood calcium levels were found to be normal, calcium excretion rates were, with one exception, more than 6 mg/kg/24 h corrected for 100 ml GFR. Hypomagnesemia of 1.5 and 1.2 mg/dl and hyermagnesuria of 1.9 and 2.5 mg/kg/24 h corrected for 100 ml GFR were found in both patients. Tubular phosphate reabsorption reached 87% and 84% at serum parathormone levels of 0.34 microgram/l and 0.31 microgram/l in the two patients, respectively. Under calcium and magnesium loading the clearance rates of calcium and magnesium were raised whilst there was only a small insignificant increase in the blood levels of these cations. Acid-base titrations showed normal excretion rates of acid and base in one patient and a mild proximal tubular acidosis in the other. Quantitative investigation of the renal concentrating and diluting capacity established a decrease in the formation of the medullary concentrating gradient in both patients.
mesh_terms: D000293:Adolescent; D002118:Calcium / Q000097:blood / Q000652:urine*; D002128:Calcium Metabolism Disorders / Q000150:complications / Q000235:genetics / Q000652:urine; D002648:Child; D003103:Coloboma / Q000150:complications; D005260:Female; D006801:Humans; D007669:Kidney Calculi / Q000000981:diagnostic imaging / Q000235:genetics; D007677:Kidney Function Tests; D008274:Magnesium / Q000378:metabolism; D008297:Male; D009397:Nephrocalcinosis / Q000000981:diagnostic imaging / Q000235:genetics; D009800:Oculocerebrorenal Syndrome / Q000145:classification; D010281:Parathyroid Hormone / Q000097:blood; D011859:Radiography; D015499:Renal Tubular Transport, Inborn Errors / Q000145:classification; D012162:Retinal Degeneration / Q000150:complications / Q000235:genetics / Q000473:pathology; D013577:Syndrome
chemical_list: D010281:Parathyroid Hormone; D008274:Magnesium; D002118:Calcium