Bacteria in the intestinal lumen metabolize bilirubin to a series of other compounds which are ultimately eliminated either in feces or, after reabsortion, in urine.
The major metabolite of bilirubin in feces is sterobilin, which gives feces their characteristic brown color. If excessive quantities of either free or conjugated bilirubin accumulate in extracellular fluid, a yellow discoloration of the skin, sclera and mucous membranes is observed - this condition is called icterus or jaundice. Determining whether the excessive bilirubin is free or conjugated can aid in diagnosing the cause of the problem.
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Home Books Gastrointestinal Physiology, 2e. Previous Chapter. Next Chapter. AMA Citation Chapter Click on the pictures to enlarge. The liver is brown-black because of the large amount of brownish coarse pigment stored in the hepatocytes. Typically there is no intrahepatic cholestasis in this condition.
The pigment predominates in the centrolobular zone. T here could be a moderate portal fibrosis in older patients. The pigment is stored in lysosomes like lipofuscin. Bile canaliculi do not contain bile. According to studies conducted in Corriedale sheep, the pigment contains a melanin-like component and and its formation is attributable to a defect of excretion of epinephrine metabolites.
This is a condition similar to Dubin-Johnson. There is intermittent jaundice with conjugated hyperbilirubinemia, similar clinical course, excellent prognosis but no pigment in the liver tissue. A syndrome characterized by recurrent attacks of rather severe jaundice.
The attacks start usually before puberty but they may start later. They are preceded by weeks of pruritus malaise, anorexia followed by. It may last from tow weeks to two years.
Nausea, vomiting , abdominal pain and skin rash occur in some cases. An affected individual may have up to 30 attacks during his life.
Alpa-glutamyl transferase GGT is elevated. Serum bile acids are elevated folds. Transaminases are occasionally markedly elevated. These abnormalities and the clinical symptoms disappear completely in disease-free intervals. In the cholestatic phase there is acinar zone 3 cholestasis with bile plugs and mononuclear cell infiltration in the cholestatic area.
In some cases there may be mild hepatocytic damage and portal mononuclear infiltrate. These changes do not produce any fibrosis or cirrhosis. Liver biopsies taken during clear intervals were normal. The disorder is rather rare and appears to be familial with autosomal recessive character. This disorder is clinically and biochemically similar to benign intrahepatic cholestasis. It occurs in the third trimester of pregnancy when the estrogen level is the highest and disappears postpartum. The affected subjects appear to belong to families with benign intrahepatic cholestasis trait.
Gonadal steroid appear to ply a determining role in the cause of this syndrome. Histology of the liver shows centrolobular cholestasis similar to benign intrahepatic cholestasis.
The disorder is safe for the mother but not for the fetus who will suffer premature births and stillbirths due to placental infarcts. The mothers have higher incidence of gallstones. Sometimes the disorder manifests itself only with presence of pruritus without jaundice. Pruritus gravidarum. The patients are not severely ill as in fatty liver of pregnancy, hepatitis, obstructive jaundice.
Many drugs produce cholestasis. The first cases reported were due to chlopromazine and synthetic steroids now out of market Nilavar. Synthetic oral contraceptives are high in the list. They appeared to act on sensitivity base and affect only sensitive individuals. Many appear to impair the secretory function of the hepatocytes. And the list is increasing with the advent of new drugs. The liver in these cases may show. It is attributable to the combined effect of bilirubin overload deriving from blood transfusions and to defect of hepatocytic secretory function.
Usually the jaundice appears in postoperative days and disappears in one or two weeks, Hyperbilirubinemia is predominantly conjugated with rater normal alkaline. It is a form of intrahepatic cholestasis. The hyperbilirubinemia is conjugated in all cases. Elevation of serum alkaline phosphatase in some cases. Jaundice may be caused by liver disease hepatitis , blood disorders hemolytic anemia , or blockage of the tubes bile ducts that allow bile to pass from the liver to the small intestine.
Mild jaundice in newborns usually doesn't cause problems. But too much bilirubin hyperbilirubinemia in a newborn baby can cause brain damage kernicterus and other serious problems. So some babies who develop jaundice may need treatment to lower their bilirubin levels.
For a heel stick blood sample, several drops of blood are collected from the baby's heel. The skin of the heel is first cleaned with alcohol and then punctured with a small sterile lancet. Several drops of blood are collected in a small tube.
When enough blood has been collected, a gauze pad or cotton ball is placed over the puncture site. Pressure is maintained on the puncture site briefly. Then a small bandage is usually applied.
Instead of the standard heel stick, some hospitals may use a device called a transcutaneous bilirubin meter to check a newborn's bilirubin level.
This small handheld device measures bilirubin levels when it is placed gently against the skin. With this device, there may be no need to puncture the baby's skin. This is a screening test, and a blood sample will be needed if the baby's bilirubin level is high. A brief pain, like a sting or a pinch, is usually felt when the lancet punctures the skin. A baby may feel a little discomfort with the skin puncture.
When a blood sample is taken, you may feel nothing at all from the needle. Or you might feel a quick sting or pinch. There is very little risk of a problem from a heel stick. Your baby may get a small bruise at the puncture site.
There is very little chance of having a problem from this test. When a blood sample is taken, a small bruise may form at the site. Each lab has a different range for what's normal.
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