Severe Osteomalacia and Fractures Secondary to Vitamin D Deficiency

Background: Vitamin D deficiency is a common entity among the elderly. Low vitamin D levels can lead to poor bone mineralization, in addition to elevations in PTH levels with resultant increases in bone turnover. However, severe Vitamin D deficiency causing osteomalacia has become uncommon in the United States due to increased screening and treatment. Vitamin D supplementation is a mainstay of therapy for osteoporosis, yet its effect on bone density is generally thought to be modest. We present here an extreme case of vitamin D deficiency leading to severe secondary hyperparathyroidism and bone demineralization, with excellent response to supplementation. Clinical Case: Patient was a 73-year-old woman with hypertension who presented to the ER with acute on chronic back and lower extremity pain. She had these pains for about a year, but they had worsened over the last 4 days. She had been homebound for the past 1–2 years due to severe pain while ambulating, reported a five-inch loss of height and 50 pounds weight loss, and maintained a vegan diet. She had not had medical care in 15 years. Imaging studies demonstrated a displaced left femoral neck fracture, a nondisplaced right femoral neck fracture, multilevel thoracolumbar compression fractures, and a nondisplaced right scapular fracture. Blood tests revealed normal renal function, calcium 8.6mg/dL (nl 8.5–10.5), phosphorus 2.6mg/dL (nl 2.5–4.5), and alkaline phosphatase 2,821U/L (nl 45–164). Secondary osteoporosis workup was negative for hypercalciuria or multiple myeloma, but was notable for a PTH level of 2,190 pg/mL (nl 10–65) and 25-OH Vitamin D level of <5ng/mL (nl >30). C-telopeptide was measured at 3,346 pg/mL (nl <1000) and osteocalcin >300ng/mL (nl 8–32). DEXA scan showed T-scores of -4.2 at the lumbar spine and -6.8 at the distal forearm. She was started on high-dose vitamin D supplementation, with serum Vitamin D level rising to 42.1ng/mL after 6 months of treatment. This corresponded to a decrease in PTH to 141.1pg/mL and alkaline phosphatase to 375U/L. Repeat DEXA two years later showed 52.8% increase in bone mineral density at the lumbar spine, and 27.1% increase at the forearm. The patient’s body pains have significantly improved and she is now ambulatory again. Conclusions: Vitamin D deficiency is an uncommon cause of severe bone demineralization in the United States. However, in certain high-risk populations, it can present with debilitating osteomalacia and numerous pathologic fractures. Even in cases of osteoporosis with severe PTH elevation, Vitamin D deficiency must be ruled out as a potential secondary etiology, as it can be easily treated with potentially dramatic response.