Endocrine Abstracts

Introduction: X-linked hypophosphatemic rickets (XLH) is a very rare cause of growth deficiency that can be diagnosed even in adulthood. The mutation of the PHEX gene in these patients causes higher levels of FGF-23 and hypophosphatemia.

Case presentation: A 20-year-old male patient was admitted into our clinic due to short stature, walking difficulties, joint and muscle pain, predominantly in the lower limbs. He described the presence of symptoms since childhood. The family history revealed that his mother, aunt and maternal grandfather had short stature with similar appearance. In paediatrics service he was diagnosed with familial hypophosphatemic rickets at the age of two and was treated with 1-alpha(OH)D3 and a rich phosphorus diet until the age of seven. No genetic or FGF- 23 testing was performed at that time. On physical exam, the patient had a height of 156 cm, a disharmonic dwarfism, many dental abscesses, waddling gait, genu varum and lower limbs deformities. The laboratory tests showed a normal serum calcium and hypophosphatemia with FePO4 of 24%. Radiological findings revealed bilateral coxarthrosis and genu varum. Due to heredity, XLH was the most likely diagnosis in this case. FGF-23 was in the upper normal range confirming the diagnosis. Genetic testing and counselling were recommended, for the analysis of the PHEX gene mutation, due to the desire of this patient to have a child.

Conclusion: Being so rare, XHL as a cause of short stature can be easily overlooked. XLH should be considered in the differential diagnosis of short stature with low serum phosphate, regardless of age.