Acute changes in calcium and bone metabolism during methylprednisolone pulse therapy in rheumatoid arthritis.

Corticosteroids (CS) decrease bone formation and enhance bone resorption and this can lead to osteopenia. Bone metabolism was studied during the administration of huge amounts of CS (1000 mg methylprednisolone) over a short period of time in 10 patients with persistently active rheumatoid arthritis. The effects could be divided into those occurring within 24 h: (a) a decrease in bone resorption (urinary excretion of calcium and hydroxyproline) and bone formation (alkaline phosphatase); (b) a decrease in renal excretion of calcium; (c) an increase in concentration of serum 1,25-dihydroxy-cholecalciferol and those secondary effects arising after 24 h; (d) a decrease in serum calcium due to the decrease in intestinal Ca absorption and the decrease in renal tubular reabsorption of Ca; (e) an increase in serum PTH concentrations. In a previous study it was found that these changes normalized within a few days after completion of the CS treatment.