[Osteoporosis].

Abstract

Liver cirrhosis may be accompanied by osteoporosis and, rarely, osteomalacia. Normal liver function is required for normal digestion and absorption of calcium-containing nutrients. The liver plays an important role for the metabolisation of vitamin D: the 25-hydroxylation takes place in the liver. However, the respective enzymatic capacity is not limited by liver diseases except for almost complete liver insufficiency. Therefore, true hypovitaminosis D only rarely plays a role in hepatic osteopenia, but direct toxic effects on bone forming cells (osteoblasts) are discussed: e.g. by bile salts. Coexisting hypogonadism leads to further bone loss. Patients with primary biliary cirrhosis in part present with osteoporosis and fractures. Bone histology reveals normal resorption, but decreased formation. Calcitropic hormones are generally normal. Chronic alcoholism induces the same histologic picture in bone, i.e. normal resorption and diminished formation. These changes are reversible after abstinence and as long as of cirrhosis has not yet developed. Patients undergoing liver transplantation due to end stage liver insufficiency including cirrhosis present with diminished bone mass before receiving a new liver, and they show further bone loss after the transplantation due to immunosuppressive treatment including glucocorticoids. There is no specific treatment of bone loss or osteoporosis due to liver cirrhosis. Preventive efforts should be devoted to the avoidance of suboptimal calcium and vitamin D supply, immobilization, and hypogonadism. Fluorides may increase bone mass after liver transplantation--perhaps they are also useful in liver cirrhosis. Antiresorption agents like calcitonins or bisphosphonates may be cautiously tried.