CHANGES IN CALCIUM AND BONE METABOLISM DURING TREATMENT WITH LOW-DOSEPREDNISONE IN YOUNG, HEALTHY, MALE-VOLUNTEERS

The effect of low dose prednisone on calcium and bone metabolism was e valuated in 8 healthy, young, male volunteers. Sodium and calcium inta ke were kept stable during the whole study period of 7 weeks. Week 0 w as the baseline period; during week 1, 3 and 5 prednisone (10 mg/day) was given, during week 3 together with 500 mg elementary calcium and d uring week 5 with 4000 IU vitamin D on alternate days. During week 2, 4 and 6 no medication was given. No changes occurred in fasting urinar y excretion of calcium or hydroxyproline, nor in serum levels of alkal ine phosphatase, 25-Vitamin D, PTH, creatinine and inorganic phosphoru s. A rapid decrease of serum osteocalcin during prednisone intake was found (p < 0.01). This dip also occurred during prednisone acid vitami n D treatment, but did not occur when calcium was added to prednisone, although the baseline value was lower at the start of combined treatm ent with prednisone and calcium. Serum calcium decreased during predni sone (p < 0.05), but when prednisone was given together with calcium, an increase of serum calcium was found. (p < 0.05) It is concluded tha t 10 mg prednisone/day decreases bone formation, as shown by its effec t on osteocalcin, while no influence is seen on bone resorption. Thus, prednisone, even when used in low doses, influences bone metabolism b y uncoupling bone formation (decreased) and bone resorption (unchanged ). These data suggest that the Cs-associated decrease in serum osteoca lcin and in serum calcium does not occur during calcium suppletion.