The liver in systemic illness

The size of an organ does not always reflect its relevance, but in the case of the liver, this assumption may be true. The liver plays a central role in all metabolic processes in the body. Apart from processing fat, carbohydrates, and proteins to supply energy, the liver is responsible for detoxification and protects the organism from pathogens. Moreover, storage of vitamins and minerals, in particular iron and copper, occurs in the liver, rendering possible their provision in times of deprivation. It is therefore not surprising that during the course of many systemic diseases, the liver gets involved and may be injured. In general, mechanisms that may cause liver damage can be of metabolic, toxic, vascular, or immunologic origin. Despite the large variation of pathogens that affect the liver, the final result is hepato- and/or cholangio-cellular injury that may either end in cirrhosis when the injury is chronic or liver failure in the case of acute severe damage. Since the first step of treatment is the correct diagnosis of liver involvement in a systemic disease, we aim to give an overview of paediatric illnesses that do not primarily affect the liver but may still cause more or less severe liver injury. Treatment of the underlying disease and thereby terminating the pathophysiological mechanism lead to resolution of the liver disease in most of the cases; nevertheless specific interventions ranging from pure observation to avoidance of certain liver toxic medications or even maximal therapy as liver transplantation may sometimes be required.