Bone Mineral Density is Decreased in Patients with Systemic Sclerosis and Correlates With Serum Intact Parathormone Levels: A Cross-Sectional Study

Abstract

Objective: To study bone mineral density (BMD) in Indian patients with systemic sclerosis and objectively verify whether an association exists between osteoporosis and systemic sclerosis. Methods: Adult patients suffering from systemic sclerosis (as per the 2013 American College of Rheumatology classification criteria for systemic sclerosis) attending the rheumatology clinic at Post Graduate Institute of Medical Education and Research, Chandigarh, India were recruited. BMD was measured using dual energy x-ray absorptiometry (DXA) and serum Vitamin D and iPTH levels were estimated. The 10-year probability of sustaining an osteoporotic fracture was estimated using the World Health Organisation fracture risk assessment tool with the Indian population reference. Results: 100 patients were included (89 women). Interstitial lung disease and pulmonary arterial hypertension were seen in 48 and 18 patients, respectively. Median (range) serum 25 hydroxy Vitamin D level was 17 ng/ml (3.7-225.7 ng/ml). Mean serum iPTH level was 79.6±38.1 pg/ml. 55 patients were categorized as Vitamin D deficient, 24 as insufficient, and 21 as Vitamin D sufficient. 21 patients had iPTH values above 75 pg/ml. 28% had osteoporosis of the lumbar spine while 6% had osteoporosis of the femoral neck. Serum iPTH correlated inversely with low bone mass at the hip (P = 0.023, r2 = 0.121). Low bone mass did not correlate with age, postmenopausal status, low BMI, corticosteroid use, serum 25 hydroxy Vitamin D levels, disease duration, presence of interstitial lung disease or pulmonary arterial hypertension. Conclusion: Low bone mass is highly prevalent in patients with systemic sclerosis and is associated with elevated serum iPTH levels.

Keywords

• Bone mineral density
• osteoporosis
• systemic sclerosis