Introduction: Patients with primary adrenal insufficiency receive long - term glucocorticoid replacement therapy, which may cause osteoporosis

The aim of the study was to assess the effect of glucocorticoid replacement therapy in patients with Addison´s disease on bone mineral density (BMD), parameters of calcium - phosphate (Ca-P) metabolism as well as on bone turneover markers. The study group consisted of 46 patients with Addison´s disease (12men, 17 pre- and 17 postmenopausal women, the control group consisted of 44 healthy individuals (8 men, 16 prepre- and 16 postmenopausal women). Ca-P metabolism parameters, bone turnover markers and adrenal hormones were examined in all groups. BMD was measured by dual-energy X-ray absorptiometry in the lumbar spine (BMD lumb) and forearm (BMDfore). We did not confirm an increased prevalence of osteoporosis and osteopenia in patients with Addison´s disease. BMD values did not correlate with hydrocortisone (HCT) doses, HCT doses calculated on body weight and body surface area as well as with duration of substitution treatment. Patients with daily HCT doses > 25 mg had significantly lower BMD in lumbar spine compared with patients with daily HCT doses 25 mg. In study group we observed decreased levels of adrenal androgens, in women also estradiol. Decreased level of serum calcium and increased level of osteocalcin, bone alkaline phosphatase, 25- hydroxyvitamin D were present in women with Addison´s disease. RANKL/OPG ratio was higher in patients with Addison´s disease compared with controls. Glucocorticoid replacement therapy is not a significant risk factor for development of osteoporosis in patients with Addison disease, because this therapy only physiologically replaces endogenous cortisol deficiency. An increased RANKL / OPG ratio may indicate a relative lack of OPG. It is possible that female patients, despite adequate substitution, have an increased bone turnover and a relatively higher risk of decrease in BMD. Potential risks are higher doses of glucocorticoid replacement therapy (HCT > 25 mg daily) and a typical steroid constellation (decreased adrenocortical androgens DHEA and DHEAS and in women also estradiol).