Predictive Values of Osteocalcin in Osteoporosis at the Kenyatta National Hospital

Abstract

Background Osteoporosis is increasingly becoming a major health problem in the Kenyan population, especially postmenopausal women. Two previous hospital-based studies put the prevalence at 24.5%. The disease is debilitating and affects the overall health of the population. Complications arising from this orthopaedic condition can be catastrophic; ranging from hip fractures to lumbar fragility fractures. To mitigate its effect, there is a need to identify early diagnostic modality. This allows planned intervention including pharmacological approach and lifestyle modifications aimed at preventing the progression of the disease. Currently, the gold standard for the diagnosis of the disease is Dual Energy X-ray Absorptiometry (DXA) scan. This is not affordable and accessible to many people in the Kenyan setting according to the International Osteoporosis Society audit. Therefore, the search for an alternative, affordable and accessible marker to pick up early osteoporosis and to serve as a clinical screening and diagnostic tool is a necessity. Objective To correlate Osteocalcin level with DXA findings in the diagnosis of osteoporosis in the Kenyan setting, in postmenopausal women and assess fracture risk Methodology This is an analytical cross-sectional study done on postmenopausal women ages 50 years and above. The study period was from 1st March –31st May 2018, at the Kenyatta National Hospital in Nairobi, Kenya. Participants were recruited at the Orthopaedic Clinic of Kenyatta National Hospital. These participants were taken to Medanta AfriCare in Nairobi for the neck of both femurs and lumbar spine densitometry. Samples of blood were simultaneously taken from each patient, centrifuged and transported to Lancet Kenya at 20 degrees Celsius for determination of Osteocalcin levels. Results A total of 61 postmenopausal women were assessed for necks of both femur and lumbar vertebrae DXA findings and serum Osteocalcin levels. 11 women constituting 18% were found to be osteoporotic while 22 (36%) were osteopenic. BMI did not have any association with BMD levels of both femur and lumbar spines and with serum Osteocalcin levels. There was a correlation between Osteocalcin levels and DXA findings for the neck of the femur. Women with normal T-score of greater than -1 SD were found to have serum Osteocalcin levels less than or equal to 15.5 ng/ml while those with Osteopenia (T scores between -1 and -2.5 SD) had Osteocalcin levels between 15.6 – 25 ng/ml. Women with Osteoporosis ( Tscore ≤ -2.5 SD) had consistent Osteocalcin levels greater than 25.1 ng/ml). Conclusion Eighteen percent of postmenopausal women are osteoporotic. The study revealed that there is a strong correlation between Serum Osteocalcin levels and BMD levels in postmenopausal women. Serum Osteocalcin levels are predictive of DXA findings. Therefore Serum Osteocalcin levels should be considered as a screening tool for osteoporosis in postmenopausal women, especially in low resource communities.