Phosphorus and phosphate irons play critical roles in bone structure and essential cellular
The purpose of this study is to learn more about the factors and hormones that regulate
phosphorus in the body by collecting blood and urine samples from patients with disorders of
Both children and adults will be enrolled in this study. Researchers will collect blood and
urine samples from participants on multiple occasions (2 to 6 times). Some blood specimens
will be taken after an overnight fast and participants may be asked to collect all their
urine during a 24-hour period. Researchers will analyze these blood and urine samples to
better understanding how the body handles phosphorus.
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
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
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.
Patients of any age, gender or ethnicity who will help fulfill the objectives laid out in
We propose to study patients primarily enrolled in other clinical center protocol(s).
They will continue to receive treatment/ interventions per the original protocols.
Patients with significant cognitive impairment who are unable to give informed consent or
patients having other significant mineral disturbances that could confound the parameters
being studied will be excluded.