ABSTRACT: The prevalence of secondary contributors to osteoporosis in our population of SE Asian patients is high. Though various low thresholds Z score values have been proposed as suggestive of a high likelihood of secondary osteoporosis, they appear to have only limited discriminatory value in identifying a secondary cause.
Many patients with osteoporosis have significant secondary contributors towards their bone loss. The sensitivity and diagnostic utility of using Z score thresholds to screen for secondary osteoporosis have not yet been convincingly demonstrated nor has there been any previous attempt to estimate the prevalence of secondary osteoporosis in South East Asia. We aimed to study the prevalence of commonly recognized contributors and to determine the discriminatory ability of Z score thresholds in screening for them in Singaporean men and post-menopausal women with osteoporosis.
Three hundred thirty-two consecutive patients seen at the osteoporosis clinic of the largest hospital in Singapore were evaluated. The frequencies of the different contributors were determined and sensitivities, specificities, and positive and negative predictive values (PPV and NPV) of pre-specified Z score cut-off values calculated.
Vitamin D deficiency was present in 18.5% of the patients, hyperthyroidism in 10.11%, primary hyperparathyroidism in 1%, secondary hyperparathyroidism in 6%, hypercalciuria in 21.63%, glucocorticoid use in 8.43%, and hypogonadism in 9.4% of males. A Z score value of <-1 had a sensitivity of 71.7 % and NPV of 66.2 % in identifying the presence of a secondary contributor in post-menopausal women. The sensitivity and NPV of a similar threshold in men was 59.1 and 40 %, respectively. ROC curves used to investigate various Z score diagnostic thresholds for sensitivity and specificity showed that they provided poor predictive value for the presence of secondary osteoporosis.
Secondary contributors are common in our patients with osteoporosis. Z score diagnostic thresholds have only limited value in discriminating between primary and secondary osteoporosis.
Archives of Osteoporosis 12/2012; 7(1-2):49-56.
Archives of Osteoporosis 10/2012;
ABSTRACT: Limited data are available regarding patterns of bone loss in South East Asian renal transplant patients. We aimed to determine the prevalence of low bone density and factors contributing to bone loss in Singaporean patients in the first year after renal transplant.
Seventy-nine consecutive patients who underwent renal transplant were evaluated. Bone mineral density (BMD) was evaluated at 0 (baseline), and at 6 and 12 months after transplant. Baseline parathyroid hormone and vitamin D levels were also assessed. Multivariate regression models were used to investigate the relationship between the different variables and BMD.
Thirty-six patients (45.6%) had low BMD at baseline. Factors correlating with the low BMD were older age, postmenopausal status, and tertiary hyperparathyroidism (P<0.0005, 0.009, and 0.027, respectively). There was a linear decrease in total hip and lumbar spine BMD from baseline to 12 months, the decrease from baseline to 6 months being significant (P=0.019 for total hip and P<0.0005 for lumbar spine). Patients with tertiary hyperparathyroidism had a greater risk of decrease in BMD at 6 months compared with patients with secondary hyperparathyroidism (odds ratio=13.5, confidence interval: 1.3, 144.4) and with those who had parathyroidectomy (odds ratio=34.9; confidence interval: 2.0, 598.8).
The prevalence of low BMD in this population of renal transplant recipients was high. Parathyroid status was the only independent factor that correlated with low BMD at baseline and subsequent bone loss highlighting the critical role of this hormone in bone metabolism after renal transplant.
Transplantation 09/2011; 92(5):557-63. · 4.00 Impact Factor