In hypophosphatemic rickets, calcium levels may be within or slightly below the reference range; alkaline phosphatase levels will be significantly above the reference range.Carefully evaluate serum phosphate levels in the first year of life, because the concentration reference range for infants (5.0–7.5 mg/dL) is high compared with that for adults (2.7–4.5 mg/dL).Serum parathyroid hormone levels are within the reference range or slightly elevated, while calcitriol levels are low or within the lower reference range. Most importantly, urinary loss of phosphate is above the reference range.The renal tubular reabsorption of phosphate (TRP) in X-linked hypophosphatemia is 60%; normal TRP exceeds 90% at the same reduced plasma phosphate concentration. The TRP is calculated with the following formula:1 - [Phosphate Clearance (CPi) / Creatinine Clearance (Ccr)] X 100

Treatment
Oral phosphate, calcitriol; in the event of severe bowing, an osteotomy may be performed to correct the leg shape. The monoclonal antibody burosumab was first licensed in February 2018 by the European Medicines Agency, then licensed by the Food and Drug Administration in the United States of America in June 2018 as the first drug targeting the underlying cause for this condition.The leg deformity can be treated with Ilizarov frames and CAOS. It is also treated with medications including human growth hormone, calcitriol, and phosphate. Society and culture
International XLH Alliance – an alliance of international patient groups for individuals affected by XLH and related disorders. Jennyfer Marques Parinos is a Paralympic bronze medalist from Brazil who has XLH. She competes under a class 9 disability.
X-linked hypophosphatemia (XLH) is an X-linked dominant form of rickets (or osteomalacia) that differs from most cases of dietary deficiency rickets in that vitamin D supplementation does not cure it. It can cause bone deformity including short stature and genu varum (bow-leggedness). It is associated with a mutation in the PHEX gene sequence (Xp.22) and subsequent inactivity of the PHEX protein. PHEX mutations lead to an elevated circulating (systemic) level of the hormone FGF23 which results in renal phosphate wasting, and locally in the extracellular matrix of bones and teeth an elevated level of the mineralization/calcification-inhibiting protein osteopontin. An inactivating mutation in the PHEX gene results in an increase in systemic circulating FGF23, and a decrease in the enzymatic activity of the PHEX enzyme which normally removes (degrades) mineralization-inhibiting osteopontin protein; in XLH, the decreased PHEX enzyme activity leads to an accumulation of inhibitory osteopontin locally in bones and teeth to block mineralization which, along with renal phosphate wasting, both cause osteomalacia and odontomalacia. For both XLH and hypophosphatasia, inhibitor-enzyme pair relationships function to regulate mineralization in the extracellular matrix through a double-negative (inhibiting the inhibitors) activation effect in a manner described as the Stenciling Principle. Both these underlying mechanisms (renal phosphate wasting systemically, and mineralization inhibitor accumulation locally) contribute to the pathophysiology of XLH that leads to soft bones and teeth (hypomineralization, osteomalacia/odontomalacia). The prevalence of the disease is 1 in 20,000.X-linked hypophosphatemia may be lumped in with autosomal dominant hypophosphatemic rickets under general terms such as hypophosphatemic rickets.