Clinical Relevance - Focus on Intrahepatic Cholestasis of Pregnancy (ICP)
TBA level determination in pregnant women is considered to be the most important biomarker for diagnosis and monitoring of ICP, also known as obstetric cholestasis (OC) [10-12]. ICP is the most common liver disease that occurs during pregnancy; usually during the third trimester of pregnancy. The cause of obstetric cholestasis is not fully understood but it is believed to be multifactorial with genetic, environmental and hormonal factors being involved . The reversible type of hormonally influenced cholestasis leads to a restricted bile flow through the gallbladder and in turn, to an accumulation of bile acids in the liver and possibly in the bloodstream [7,14]. The Pregnancy-cholestasis is characterized by strong itching (pruritus) . During ICP, TBA levels rise up to 220 µmol/L , leading to an increased risk of fetal distress, premature birth or even stillbirth. TBA concentrations above 40 µmol/L may be fetotoxic .
The incidence of ICP varies from 0.02% to 2.4% of pregnancies and about 70% of them present in the third trimester (mean 31 weeks) . In addition, the incidence also varies significantly, depending on geographical location and ethnicity, with rates up to 15% in Chile and Bolivia and less than 1% in Europe [15,16]. A higher incidence is seen in twin pregnancies, following in-vitro fertilization, in women older than 35 years, with history of cholestasis in previous pregnancies and in women with history of biliary disease [16-18].