Spinal Ossification Due to Hypoparathyroidism: A Case Report

We present a 53-year-old female patient who was admitted for renal failure and where spinal ossification similar to ankylosing spondylitis was detected due to hypoparathyroidism. On physical examination, she had extreme inability to move her neck and waist, as in ankylosing spondylitis. X-Ray examination showed full-length paravertebral calcification and ossification but no sacroiliitis. She had a history of thyroidectomy 20 years ago. Laboratory examination revealed iPTH 3.3 pg/ml, Ca 4.4 mg/dl, P 5.0 mg/dl, Hb 8.9 gr/dl, Cr 6.7 mg/dl, and albumin 1.8 gr/dl. Idiopathic hypoparathyroidism may cause various musculoskeletal findings including ligamentous and tendinous ossification and soft tissue calcification. Ligament or entheseal ossifications may mimic or coexist with the radiological changes of diffuse idiopathic skeletal hyperosteosis (DISH) or ankylosing spondylitis. The diagnosis of ankylosing spondylitis can be excluded in the absence of sacroiliitis. DISH is a musculoskeletal disorder, rarely seen before the age of 50, and is characterized by ossification of the anterior longitudinal ligament of the spine and various extraspinal ligaments. DISH is diagnosed with typical radiographic abnormalities such as anterior longitudinal ligament ossification and osteophytes on direct roentgenograms. In conclusion, hypoparathyroidism may cause various musculoskeletal findings and is usually diagnosed many years after its onset because of its nonspecific symptoms and DISH-like radiological features.