The purpose of this study was to investigate the possible role of diminished phosphate clearance by the fetal kidney in production of relative fetal hyperphosphatemia. Stimuli known to affect renal phosphate clearance in adults were investigated in young fetal lambs. Our studies confirm that the fetal lamb kidney responds to exogenous and endogenous parathyroid hormone (PTH) with inhibition of tubular phosphate reabsorption. Renal tubular phosphate reabsorption in the fetus is in part related to sodium reabsorption. These studies indicate that so-called “immaturity” of renal phosphate clearance in utero is not a significant factor in production of fetal hyperphosphatemia.Speculation
The fetal kidney responds early in gestation to stimuli that influence renal clearance of phosphate in adults.