An evaluation of the physicochemical risk for renal stone disease during pregnancy

Seventeen subjects were studied during the third trimester of pregnancy (PG ) and postpartum (NPG) to evaluate the effect of pregnancy on the physicoch emical risk of renal stone disease. Levels of urinary saturation for calciu m oxalate (CaOx), brushite (Br), uric acid (UA), and monosodium urate (NaU) were determined as well as urinary excretions of stone-forming elements. I n addition to urinary calcium excretion, assessment of calcium metabolism i ncluded serum calcium and parathyroid hormone. Urinary calcium excretion wa s 251 +/- 127 mg/day during pregnancy and 121 +/- 67 mg/day post partum (p < 0.001). This was associated with a higher intake of dietary calcium and a ltered renal handling, of calcium with an increase in the filtered load and a decrease in renal tubular reabsorption. The increase in urinary calcium resulted in a higher level of saturation of the urine for calcium oxalate ( NPG 2.1 +/- 1.0 vs PG 3.0 +/- 1.1, p < 0.02) and brushite (NPG 1.2 +/- 0.9 vs PG 1.9 +/- 1.1, p < 0.05) compatible with an increased risk of stone for mation.