Saturday, 5 January 2008

True or false: in liver disease you are at risk of both hypoglycaemia and hyperglycaemia

True. Here's why.

The liver is the major site of the body's systemic glucose regulation. Basically, it can raise the blood glucose level by the process of gluconeogenesis or by breaking down its large supply of glycogen. So, if enough liver cells are destroyed in liver disease, you can get (life-threatening) attacks of hypoglycaemia.

Also, the blood supply from the gut passes via the liver before hitting the rest of the body - it gets there in the portal system. As the blood passes through the liver, the hepatocytes (liver cells) extract some of the glucose from the meal you've just eaten. However, in certain types of liver disease, particularly in cirrhosis, this delicate portal blood supply is disrupted and partially blocked. As a result, the blood backs up and finds alternative routes to the systemic circulation - thus bypassing the liver. As a result, there is less opportunity for the hepatocytes to remove glucose before it hits the systemic circulation - and the result can be hyperglycaemia.

Incidentally, this bypassing of the liver by the blood (in certain liver diseases) is referred to as portal-systemic shunting, and is a very important topic. Maybe we'll cover that at a later time.

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