Serum bile acids are used to diagnose a liver disease during pregnancy

Intrahepatic cholestasis of pregnancy (ICP) is a long, rather complicated name, for a problem that affects about 1% of pregnant women in the United States. For reasons unknown, ICP is much more common in South America, particularly the country of Chile, where it is 10 times more frequent.

What is it? It's a type of liver disease in which the flow of bile from the liver into the intestines is blocked. Normally, bile made in the liver is secreted and stored in the gall bladder where it eventually finds its way into the intestines where it aids in the digestion of dietary fats. For reasons that are poorly understood, this normal flow of bile may be interrupted during pregnancy leading to its elevation in the blood. Several studies support the idea that the reproductive hormones (mostly estrogen) plays an important role in the development of ICP.

The most common symptom of ICP is intense itching (pruritis) during the third trimester. The majority of women with ICP describe the itchiness to be most severe in the palms of the hands and the soles of the feet but it can be felt on other areas of the body. Most women with ICP develop the symptoms after the 30th week of pregnancy although it can happen earlier in pregnancy.

Apart from the itching, ICP is rather benign in women who develop it. The same cannot be said for her fetus, however. Although there is some debate about the risks of ICP to a fetus, the vast majority of reports describe several possible adverse fetal outcomes due to ICP. These include an increased risk of spontaneous preterm birth, an apgar score that is less than 7 at 5 minutes after birth, and increased rates of meconium staining of the amniotic fluid (a sign of fetal distress).

An ICP diagnosis is really one of exclusion. All other possible causes of liver impairment should be excluded before diagnosing ICP. Although several laboratory tests may be used in an ICP investigation, the measurement of serum bile acids is considered to be the most sensitive test for ICP. Standard liver function tests such as ALT and AST are likely to also be elevated but are less sensitive and specific than bile acids. Bilirubin testing is of limited value.

In normal pregnancy, the concentration of bile acids doesn't usually exceed 10 µmol/L. In ICP, concentrations of bile acids can get considerably higher, even up to 100 times greater than normal. Most evidence indicates that adverse fetal outcomes are less likely when the bile acid concentration is <40 µmol/L which allows more conservative management of the pregnancy and the ICP. Ursodeoxycholic acid (UDCA) is a naturally occurring, secondary bile acid that is often used to treat the disease. It appears to stimulate the excretion of the primary bile acids and decreases their delivery to the fetus. If the concentration of bile acids is high and the pregnancy is more than 37 weeks completed, delivery is usually the best course of action.

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One thought on “Serum bile acids are used to diagnose a liver disease during pregnancy

  1. Michael Metz

    We offer bile acids on a daily basis, pretty much 9-5 Monday-Friday. While I am very happy to support the clinicians, I don't see a need for a 24 hour service, 7 days a week.
    Who offers 24 hour 7 day a week bile acids measurement?

    Reply

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