For example, in chronic liver disease, 20–100% of patients develop hepatic osteodystrophy, which is caused by disorders of the hepatic hydroxylation of vitamin D, changes in the vitamin D receptor, an increase in serum PTH concentration (as in our study group), IGF-1 deficiency, hyperbilirubinemia, hypogonadism, osteoproteger deficiency, pharmacotherapy and malabsorption [21]. The gene discussed is VDR; the disease is hypogonadism.