Osteomalacia in Crohn's disease

Osteomalacia is a metabolic bone disorder characterized by impaired mineralization of the bone matrix. Vitamin D deficiency due to malabsorption syndromes may cause osteomalacia. This is a case of a patient with a 6-year history of seronegative spondyloarthropathy associated with Crohn's disease who was admitted to our outpatient clinic with symptoms of osteomalacia.

Osteomalacia is a metabolic bone disease characterized by an impaired mineralization of the bone matrix, frequently caused by disorders in vitamin D or phosphate metabolism. Vitamin D deficiency due to malabsorption syndromes (e.g., Crohn's disease, ulcerative colitis, celiac disease, and jejuno-ileal bypass for obesity) may cause osteomalacia.

A 43-year-old male presented with fatigue, low back pain, and morning stiffness. He had a 6-year history of seronegative spondyloarthropathy associated with Crohn's disease. Laboratory findings revealed low serum calcium, low 25-hydroxy vitamin D3, normal phosphorus, elevated parathyroid hormone, and alkaline phosphatase levels. Radiographs revealed grade IV sacroiliitis and Looser zones. He was diagnosed with osteomalacia due to the malabsorption of vitamin D. His symptoms and signs were relieved with supplements of vitamin D and calcium.

Osteomalacia should be considered in differential diagnosis when assessing low back pain in the patients with chronic inflammatory bowel disease. Vitamin D deficiency should be treated with vitamin D supplementation in patients with Crohn's disease to prevent osteomalacia.