Parathyroid hormone
Parathyroid hormone-induced calcium precipitation also contributes to the formation of calcium phosphate crystals, which thus impairs the renal function. An excess phosphorus triggers calcium precipitation and reduces calcium absorption in the gastrointestinal tract. This reduces the ionized calcium concentration in blood, which further induces a compensatory parathyroid hormone response. Parathyroid hormone is reported to accelerate urinary calcium load, which results in the formation of calcium phosphate crystals in the renal distal tubules and collecting ducts.