Bilateral slipped capital femoral epiphysis in a male adolescent with familial hypomagnesemia with hypercalciuria and nephrocalcinosis (FHHNC), chronic renal failure, and severe hyperparathyroidism.

UNLABELLED: Slipped capital femoral epiphysis (SCFE) is the most common orthopedic hip disorder affecting otherwise healthy adolescents. The majority of SCFE cases are classified as idiopathic; rarely, it may be secondary to different endocrinopathies including hyperparathyroidism due to chronic renal failure (CRF). However, over the last decades, the association between SCFE and CRF has almost disappeared, probably due to better management of renal osteodystrophy. Familial hypomagnesemia with hypercalciuria and nephrocalcinosis (FHHNC, OMIM no. 248250) is a rare autosomal recessive tubulopathy characterized by renal wasting of calcium and magnesium leading to hypomagnesemia, hypercalciuria, nephrocalcinosis, and CRF. Patients usually show hyperparathyroidism before the onset of advanced CRF caused by FHHNC-related metabolic disturbances. We report on a 15-year-old patient with FHHNC and CRF who developed extreme hyperparathyroidism and high-grade bilateral SCFE after self-discontinuation of supportive treatment of underlying conditions.
CONCLUSION: We believe that SCFE was caused not only by untreated CRF but also by metabolic disturbances related to FHHNC. To prevent this complication, careful management of disturbances of calcium, phosphate, and magnesium homeostasis seems to be crucial.