Effect of glucocorticoids exposure on serum osteocalcin levels

Glucocorticoids (GCs) treatment has a profound effect on bone turnover and the mechanism is complex and not elucidated completely. One of the actions on bone explained by many studies is its effect on serum osteocalcin levels. To investigate changes in the osteocalcin levels among patients who are on GCs and to correlate these levels with various doses of different GCs, a prospective observational study on 88 subjects who were on GC therapy was undertaken. Mean age of subjects was 42.29 ±13.86 years, with a marginal female preponderance (58%). Median dose of glucocorticoids was 1mg/kg (0.89, 2.60). Median baseline serum osteocalcin concentration was 4.4ng/ml (2.2, 9.0), which reduced significantly after starting GC therapy to 2.2ng/ml (1.01, 4.74) (p value=0.009). The median dose of prednisolone was 0.9 (0.72, 0.90) and of methylprednisolone 2.6 (2.1, 3.4) mg/kg. The serum osteocalcin level was reduced significantly (p<0.01), irrespective of GCs. We found that osteocalcin levels were negatively correlated with the dose of prednisolone (r= -0.06, p=0.6) and methylprednisolone(r=-0.11 p=0.53). Further, a weak negative correlation was seen in patients taking less than 1mg/kg and more than 1 mg/kg (r=-0.21 p value=0.32 and r=-0.352 p value-0.005), showing greater reduction in patients on higher doses. Osteocalcin reduction is solely dependent on dose of glucocorticoids, not on type of glucocorticoids. This may have important clinical implications and may help to reduce bone related side effects.