Hypophosphatemic rickets: A case of recurrent pathological fractures

Renal phosphate-wasting disorders are the most common form of hereditary rickets and osteomalacia in western countries, but are rarely reported in India. Therefore, we report here a case of hypophosphatemic rickets.

To report a case of hypophosphatemic rickets presenting with recurrent pathological fractures.

A 34-year-old premenopausal lady presented with recurrent pathological fractures, bone pain, and muscle weakness since 14 years of age. A thorough history was taken followed by clinical examination, and relevant biochemical and radiological investigations were done.

Height was 125 cm, arm span 145 cm, body weight 30 kg, and body mass index (BMI) 19.2 kg/m(2). Dental caries, kyphoscoliosis, shortening of left lower limb, bilateral coxa vara deformity of knee, muscle weakness, and bone tenderness were present. Calcium was 9.4 mg/dL, phosphorus: 1.8 mg/dL, albumin: 4.0 gm/dL, alkaline phosphatase: 360 U/L, creatinine: 0.4 mg/dL, a normal ammonium chloride (NH4Cl) loading test,24-hour urine calcium excretion: 102 mg/day, 25-hydroxyvitamin D3 [25(OH)D3]: 21.6 ng/mL, intact parathyroid hormone (PTH): 43.74 pg/mL, fraction excretion of phosphate (PO4): 40%, tubular maximum reabsorption of phosphate per unit of glomerular filtrate (TmP/GFR): 0.65 mg/dL, and fibroblast growth factor (FGF)23: 321.4 RU/mL. Skeletal X-rays showed multiple old fractures and pseudofractures. Magnetic resonance imaging (MRI) of the whole body showed no evidence of tumor. Fludeoxyglucose ((18)F)-positron emission tomography (FDG-PET) computed tomography (CT) scan revealed metabolically active marrow with multiple areas of fracture and FDG-avid lesions in both lungs but no CT-based findings.

Hypophosphatemic rickets or osteomalacia, possibly hereditary, is a rare cause of recurrent pathological fractures.