Intrahepatic Cholestasis of Pregnancy is diagnosed by bloodwork. The test that is used is a “Total Bile Acid” test. Liver function tests are also usually run (AST, ALT) but these are not diagnostic of cholestasis and the bile acid test must be run for diagnosis.

There are several different bile acid tests from different laboratories that are all run a little differently. These will each therefore have different reference ranges listed.

The main types of tests are:

• Enzyme tests:

  Labcorp and Mayo are the two major labs that run an enzyme test. Reference range is 0-10.

•  Quest Bile Acids, Total:

  This test is run by spectrophotometry and has a listed reference range of 0-19. Of note, this is a non-pregnancy reference range but this test can be used in pregnancy which will be described below. Note: Quest as of Feb 2023 is not running this specific bile acid test due to a supply chain issue. Quest is only doing the Fractionated and Total bile acid test noted below. You can get testing through LabCorp or sometimes your hospital can send sample to Mayo for testing. 

• Quest Bile Acids, Fractionated and Total:

  Otherwise sometimes known as “Bile Acids, Pregnancy”: This test is run by Chromatography/Mass Spectrometry and has a reference range of <8.3. It measures and reports the levels of a few different bile acids including ursodeoxycholic acid (ursodiol).

Studies comparing women with Intrahepatic Cholestasis of Pregnancy to pregnant women without cholestasis have found that a level of 10 µmol/L is usually diagnostic for ICP. Most women with normal pregnancies had bile acids below this level and most women with Intrahepatic Cholestasis (ICP) had levels above this level.^1,2,3 SMFM which is the governing board for High Risk OB physicians in the US states that above 10 is diagnostic of cholestasis of pregnancy.⁴

You do not have to have a specific type of bile acid test run in pregnancy. There is often confusion that you can only have the pregnancy bile acid test from Quest. This is incorrect. Any of these total bile acid tests can be used to diagnose ICP. In fact, studies have verified that many different tests are accurate for diagnosis. ^2,3

The confusion often comes as many OB physicians will only see a few cases of intrahepatic cholestasis of pregnancy in their careers. Often, they will go by the reference range of the test. Therefore, a lot of women who really have ICP with a level above 10 on a certain test with a higher reference range will fail to be diagnosed. This happens most often on the Quest Total Bile Acid test with its reference range of 0-19. You CAN be diagnosed on this test if your levels are above 10 µmol/L. However, some physicians are either unaware of this fact or will not diagnose based on this.

If you have elevated levels (above 10) and are not being diagnosed, you could request to have one of the other bile acid tests drawn for comparison and possible diagnosis. Of note, taking ursodiol can lower bile acids also and lead to not being diagnosed. Discuss with your physician retesting options if you are already on ursodiol.

However, if your physician will diagnose you on the total bile acid test, you do not need to have the pregnancy specific test performed. Any of the tests are valid for diagnosis.

10/16/20