Osteopetrosis, hypophosphatemia, and phosphaturia in a young man: a case presentation and differential diagnosis

Abstract

We report the case of a 30-year-old African-American male with osteopetrosis and hypophosphatemia, presenting with diffuse myalgias. Laboratory evaluation performed revealed a low serum phosphorus level with urinary phosphate wasting, low calcium, and 25-hydroxyvitamin D concentrations, as well as elevated alkaline phosphatase. Skull and pelvic radiographs revealed high bone density consistent with high bone mass found on bone mineral density reports. PHEX gene mutation analysis was negative. Patient was started on calcium and phosphorus replacement, and he clinically improved. This paper will review the different subtypes of osteopetrosis, and the evaluation of hypophosphatemia.

Figure 1

Bone mineral density (BMD) of the lumbar spine. Our patient presented with elevated bone mineral density at the lumbar spine (1.842 g/cm²). This value is 5.85 standard deviations above the mean for age- and sex-matched controls (Z-score); 5.85 standard deviations above the mean level of peak bone mass (T-score).

Figure 2

Skull films. Patient's skull films are shown. They are significant for a thickened calvarium and prominent thickening of the skull at the base with a normal and symmetric density. No narrowing of the intervertebral spaces and no fractures are seen.