X-linked hypophosphatemia (XLH) is the most common form of familial hypophosphatemic rickets and it is caused by loss-of-function mutations in the PHEX gene. Recently, a wide variety of PHEX gene defects in XLH have been revealed; these include missense mutations, nonsense mutations, splice site mutations, insertions, and deletions. Recently, we encountered a 2-year-9-month-old female with spor...

a 13 year- old girl had rickets clinically evident sicne she was 10 years of age. she received multiple doses of vitamin d3 without improvement.this patient manifested an unusal form of hypophosphatemic rickets with hypercalciuria. it is recommended that urinary calcium excretion be assessed in all patients with hypophosphatemic rickets before the initiation of any therapy

Serum phosphate levels are regulated in both calcium-dependent and -independent fashions. Active vitamin D increases while PTH decreases serum phosphate levels in association with the elevation of serum calcium. On the other hand, a calcium-independent phosphaturic factor, historically called phosphatonin is believed to exert a physiological function based on findings in hereditary and tumor-in...

Fibroblast growth factor 23 (FGF23) is a circulating factor that plays a central role in the renal reabsorption of Pi and metabolism of vitamin D. It is mainly produced by osteocytes in bone and exerts its effects on distant organs such as the kidney and parathyroid in an endocrine fashion. FGF23 increases renal Pi excretion by reducing the expression of type 2a and 2c sodium/phosphate (Na/Pi) ...

Opinions expressed in commentaries are those of the authors and not necessarily those of the American Academy of Pediatrics or its Committees. Commentaries are not peer-reviewed.

Chronic hypophosphatemia is one major cause of rickets and osteomalacia in growing children (see Preface of this volume). There are acquired and congenital forms. In most instances, the acquired forms can be controlled by acting on the underlying cause (insufficient phosphate intake, increased renal loss secondary to a mesenchymal tumor, or an altered renal tubular function). The inherited synd...