Phosphorus and phosphate ions play an important role in cellular metabolism as well as bone structure. Scientific evidence suggests that, in addition to Vitamin D and PTH systems, novel factors, such as Fibroblast Growth Factor 23 (FGF-23) and Matrix extracellular phosphoglycoprotein (MEPE), may play an important role in phosphorus regulation. These factors have been best studied in rare genetic and acquired phosphate wasting disorders such as tumor induced osteomalacia (TIO), X linked hypophosphatemia (XLH) and autosomal dominant hypophosphatemic rickets (ADHR). Patients with other abnormal phosphate regulating states such as hyperparathyroidism and hypoparathyroidism, pseudohypoparathyroidism etc. undergoing phosphorus-altering interventions may provide important insight into the role of these hormones.

We are proposing an observational study with collection of blood and urine samples to study both established (e.g. mineral ions, bone markers, PTH-Vit D system, TMP-GFR) and novel (e.g. FGF-23 and MEPE) constituents of the phosphorus metabolism pathway. Patients with abnormal phosphorus regulating states will be enrolled and we will study the natural history of their disease and the effects of specific interventions that are likely to change phosphorus balance.

The outcome will potentially aid understanding of this new field of mineral regulating hormones and generate both interest and research in phosphorus metabolism. It is hoped that this will also encourage clinical trials in treatment of phosphate wasting disorders.