Hereditary Hypophosphatemic Rickets with Hypercalciuria (HHRH)
HHRH is inherited in an autosomal recessive manner and is associated with high levels of vitamin D.
HHRH is caused by genetic mutations of the renal type 2c sodium-phosphate cotransporter (Loss of function).
The gene is located on chromosome 9q34, which contains the gene SLC34A3.
A novel mutation in this gene has also been reported in an Indian patient who had rickets since childhood and developed nephrolithiasis during adulthood.
Rickets and/or osteomalacia are the presenting feature like XLH.
Bone pain, muscle weakness, and pseudofractures are the common presenting complaints, while no dental abnormalities are reported.
Mild forms may present with hypercalciuria and nephrolithiasis without the bone disease. They are more prone to develop nephrolithiasis.
FGF23 level is normal and 1,25(OH)2D levels are appropriately elevated for low phosphorus levels.
Patients should be treated only with phosphorus supplementation.
Calcitriol should not be used.
Plasma calcitriol levels and urinary calcium excretion should be monitored.