Validation of Osteoporosis Scores with Urinary N-telopeptide Bone Marker in Assessment Bone Mineral Density in Autoimmune Rheumatic Diseases Patients

Author(s): Marwa A Besar, Youssef Abulatta, Mohamed Hussein, Mahmoud Abdelhadi

Introduction: Osteoporosis is a condition characterised by decreased bone strength. Many tools are used to assess osteoporosis e.g Dual-energy x-ray absorptiometry (DXA) and Fracture Risk Assessment Tool (FRAX). Also, different bone resorption marker can predict osteoporosis e.g Urinary N-telopeptide is a sensitive and specific marker of bone resorption. Objective: assess the validity DXA and FRAX scores in early detection of osteoporosis in autoimmune diseases. Also, serum vitamin D and urinary N-telopeptide as marker for bone resorption in them.

Method: A cross sectional observational study where a (180) autoimmune rheumatic patients were assessed by DXA, FRAX scores, serum vitamin D, serum uric acid and Urinary N-telopeptide.

Result: The mean age of studied patients (180) was 46±12.6 years old, BMI 33.7 (29.4-37.8), S Uric acid 6 (5-7), S vitamin D 26 (13.3-32), urinary Telopeptide 105 (89-175), Lt femur neck T score -0.9 (-1.5…-0.3), Lt forearm T score -0.8 (-1.7….-0.1), osteoporosis 2 (1-2), FRAX score osteoporosis % 3.7 (2.6-7.5), FRAX score hip fracture % 0.2 (0.1-0.6) and risk hip fracture 1 (1-1). Left femur neck T score and Lumbar T score were significantly correlated with age, S uric acid, percentage of FRAX score osteoporosis and FRAX score hip fracture.

Conclusion: If we suspect osteoporosis, it is better to go for urinary N-telopeptide and those who test positive can go for current gold standard DXA scan. Combination of two diagnostic tools; urinary N-telopeptide with osteoporosis scores could help early identification of high risk for fracture in autoimmune diseases.