Introduction. Treatment of multiple sclerosis (MS) cannot presently avoid repeated administration of high doses of corticosteroids. One of the most feared and best documented adverse effects is steroidinduced osteoporosis. The goal of our study was to find the relationship of the decrease in bone density to the administered cumulative dose of steroids and to other risk factors in MS, primarily to the degree of motor deficit. We have also investigated, to what degree the patients are provided with preventive measures against osteoporosis.Patients and methods.Densitometry was performed in 591 patients with MS (455 women, 136 men, age. 42.8 plus or minus 10.3 years, MS duration 12.1 plus or minus 7.7 years) in different stages of the disease (42.3 % in remitting stage, 49.8 % in secondary progression, 7.9 % in primary progression) with a various degree of motor deficit (Kurtzke EDSS of the whole group was 4.3 plus or minus 1.8). Results: Osteoporosis as defined by WHO (T-score lower than -2.5) was detected in 26.4 % of patients. Correlation with the total received dose of steroids was significant but not very high whereas correlation with the degree of immobility was very high (P < 0.001). Number of osteoporotic fractures was also more dependent on immobility than on the amount of administered steroids, furthermore, 56 % of fractures occurred in post-menopausal women. We have also found other risk factors: low calcium intake, low body mass index and high consumption of alcohol. 94 % of patients at the time of the first densitometry had been using no preventive measures against steroid-induced osteoporosis, that is, the recommended dose of D vitamin and calcium from the beginning of corticosteroid treatment. Conclusion. Osteoporosis is a significant co-morbidity of MS, primarily due to a combination of motor deficit, steroid treatment and menopause in women. Timely introduction of preventive measures according to international recommendations is necessary.

        Key words: multiple sclerosis: osteoporosis, glucocorticoids, immobility, D vitamin, calcium