Loss of a parathyroid hormone-sensitive component of phosphate transport in X-linked hypophosphatemia.

Mutant hemizygotes with X-linked hypophosphatemia lack a parathyroid hormone-sensitive component of inorganic phosphate transport in kidney; female heterozygotes retain a variable proportion of this type of transport. The residual mechanism for reabsorption in affected males allows inorganic phosphate efflux from the kidney to urine so that net "secretion" is sometimes observed; the latter is directly proportional to the serum concentration of inorganic phosphate. Calcium acts on the kidney tubule to enhance net reabsorption by this component of inorganic phosphate transport.