Autosomal Dominant Hypophosphatemic Rickets Presenting in a Phenotypically Normal Adult Female

Abstract EN

We describe a presentation of Autosomal Dominant Hypophosphatemic Rickets (ADHR) in a 22-year-old female with normal pubertal growth and development and a negative family history in first-degree relatives.

The patient presented with a 2-year history of upper and lower extremity proximal muscle pain and weakness and bilateral femoral neck and pubic bone insufficiency fractures.

She had a normal serum calcium but a low phosphate as well as 25-hydroxyvitamin D (25(OH)D) levels leading initially to a diagnosis of osteomalacia.

Urine phosphate reabsorption was low confirming a phosphate wasting disorder.

She had an elevated Fibroblast Growth Factor 23 (FGF23) level.

After Tumor-Induced Osteomalacia was ruled out by extensive imaging, she was sent for genetic testing for hereditary rickets which showed a previously reported missense variant in FGF23.

Subsequently, she found out that her father’s maternal aunt and grandfather had ‘bone disorder’ and were wheelchair-bound in adulthood.

After replenishment of vitamin D, treatment with calcitriol and phosphate leads to complete resolution of patient’s symptoms and laboratory abnormalities.