Relationship of glucocorticoid dosage to serum bone Gla-protein concentration in patients with rheumatologic disorders.

Serum bone Gla-protein (BGP) measurements in 50 rheumatic disease patients receiving long-term prednisone therapy revealed an inverse relationship (r = -0.71, P less than 0.001) between serum BGP levels and prednisone dosage. Multiple regression analysis demonstrated significant relationships (R2 = 0.72, P less than 0.001) between serum BGP1/2 and prednisone dosage, dosage2, serum creatinine, age, and an age-creatinine interaction. This model predicts the suppression of serum BGP with low dosages of steroids and 50% suppression with dosages of 20-25 mg/day.