CASE FILES: BIOCHEMISTRY
A N SW E R S TO C A SE 33: C H O L E ST A SIS
O F P R E G N A N C Y
A 26-year-old female at 35 weeks gestation with generalized pruri-
tus without a rash and slightly elevated liver transaminases and bilirubin.
Diagnosis: Cholestasis of pregnancy.
Treatment options: Oral antihistamines, cholestyramine,
Etiology of generalized itching: Increased serum bile salts and
accumulation of bile salts in the dermis of the skin.
C L IN IC A L C O R R E L A T IO N
Cholestasis of pregnancy is a condition in which the normal flow of bile from
the gallbladder is impeded, leading to accumulation of bile salts in the body.
Generalized itching and, possibly, jaundice may result. It is speculated that the
hormones such as estrogen and progesterone, which are elevated in pregnancy,
cause a slowing of the gallbladder function, leading to this disorder.
Uncomplicated cholestasis is usually diagnosed clinically by generalized itch-
ing in a pregnant woman, usually in the third trimester without a rash. Elevated
serum levels of bile salts can help to confirm the diagnosis. Elevated bilirubin
levels or liver transaminase enzymes may also be seen. The usual treatment
includes antihistamine medications for the itching. Some experts recommend
ursodeoxycholic acid, a naturally occurring bile acid that seems to improve
liver function and may reduce the serum bile acid concentration. More severe
cases may require bile salt binders such as cholestyramine or corticosteroids.
A PPR O A C H TO B IL E SALTS
Be able to describe the catabolism and metabolism of bile salts.
Biochemical mechanism of action of cholestyramine and ursodeoxy-
Bile acids: The major metabolites of cholesterol, which are synthesized in
the liver and stored in the gallbladder for use as emulsifiers in the diges-
tion of lipids. Primary bile acids are those synthesized directly from
cholesterol in the liver; Secondary bile acids are metabolites of primary
bile acids produced by the action of intestinal bacteria.