The most frequent sign of Gilbert's syndrome is an occasional yellowish tinge of the skin and the whites of the eyes as a result of the slightly elevated levels of bilirubin in the blood. In people with Gilbert's syndrome, bilirubin levels may increase and jaundice may become apparent because of:

• Illness, such as a cold or the flu
• Fasting or eating a very low-calorie diet
• Dehydration
• Menstruation
• Stress
• Strenuous exercise
• Lack of sleep

An abnormal gene you inherit from your parents causes Gilbert's syndrome. The gene normally controls an enzyme that helps break down bilirubin in your liver. When you have an ineffective gene, your blood contains excess amounts of bilirubin because your body doesn't produce enough of the enzyme.

Body normally processes bilirubin

Bilirubin is a yellowish pigment made when your body breaks down old red blood cells. Bilirubin travels through your bloodstream to the liver, where the enzyme breaks down the pigment and removes it from the bloodstream.

The bilirubin passes from the liver into the intestines with bile. It's then excreted in stool. A small amount of bilirubin remains in the blood.

Abnormal gene is passed through families

The abnormal gene that causes Gilbert's syndrome is common. Many people carry one copy of this gene. In most cases, two abnormal copies are needed to cause Gilbert's syndrome.

Although it's present from birth, Gilbert's syndrome usually isn't noticed until puberty or later, since bilirubin production increases during puberty. You have an increased risk of Gilbert's syndrome if:

• Both your parents carry the abnormal gene that causes the disorder
• You're male

The low level of the bilirubin-processing enzyme that causes Gilbert's syndrome may also increase the side effects of certain medications, since this enzyme plays a role in helping clear these medications from your body.

These medications include:

• Irinotecan (Camptosar), a cancer chemotherapy drug
• Some protease inhibitors used to treat HIV

If you have Gilbert's syndrome, talk to your doctor before taking new medications. Also, having any other condition that impairs the destruction of red blood cells may increase your risk of developing gallstones.