Bilirubin, Icterus

Recently, this problem has been approached by reverting to reading the color of the bilirubin directly. This used to be called an "Icterus Index", in which the color of the serum was compared to a dilute dichromate solution (39). However, the new approach has been to use two wavelengths. This can be used in either of two different procedures. In one procedure the reading is made at the peak for bilirubin which is at 453 nm and at an isosbestic point for hemoglobin (40). The effect on the reading due to hemoglobin is subtracted from the bilirubin value. Commercial instruments based on this principle have not been successful. 

The sinusoids transport both portal and arterial blood to the hepatocytes. The systemic blood delivered to the liver contains nutrients, drugs, and ingested toxins. The liver processes the nutrients (carbohydrates, proteins, lipids, vitamins, and minerals) for either immediate use or for storage, while the drugs and toxins are metabolized through a variety of processes known as first-pass metabolism. The liver also processes metabolic waste products for excretion. In cirrhosis, bilirubin (from the enzymatic breakdown of heme) can accumulate this causes jaundice (yellowing of the skin), scleral icterus (yellowing of the sclera), and tea-colored urine (urinary bilirubin excretion). 

Jaundice (yellow color of skin, whites of the eyes) may occur when blood levels of bilirubin exceed normal (icterus). Jaundice may be characterized by an increase in unconjugated (indirect) bilirubin, conjugated (direct) bilirubin, or both. Accumulation of bilirubin (usually unconjugiated) in the brain (kernicterus) may result in death. When conjugated bilirubin increases, it may be excreted, giving a deep yeUow-red color to the urine. Examples of conditions associated with increased bilirubin and jaundice include the following. 

Jaundice (or icterus) is defined as yellowing of the skin, scierae and fingernaii beds due to increased concentration of bilirubin in the blood (hyperbilirubinemia). 

Jaundice (also called icterus) refers to the yellow color of skin, nail beds, and sclerae (whites of the eyes) caused by deposition of bilirubin, secondary to increased bilirubin levels in the blood (hyperbilirubinemia, Figure 21.10). Although not a disease, jaundice is usually a symptom of an underlying disorder. 

Definition and causes of jaundice Jaundice (icterus) refers to the yellow color of the skin, nail beds, and sclerae caused by deposition of bilirubin, secondary to increased bilirubin levels in the blood. There are three major forms of jaundice hemolytic jaundice, caused by massive lysis of red blood cells, releasing more heme than can be handled by the reticuloendothelial system obstructive jaundice, resulting from obstruction of the bile duct and hepatocellular jaundice, caused by damage to liver cells that decreases the liver s ability to take up and conjugate bilirubin. In addition, neonatal jaundice is caused by the low activity of hepatic glucuronylation of bilirubin, especially in premature infants. 

A 49-year-old man developed scleral icterus with raised bilirubin and transaminases after using pioglitazone 15-30 mg for 6 months and 45 mg for 1 week (105). No other cause for hepatitis was found. After withdrawal his liver function improved substantially within 14 days. 

The use of the icterus index, as described by Meulengracht, for the assessment of jaundice has fallen into disrepute because of the errors caused by the presence of lipochromes, carotenoids, and other yellow pigments. Josephson (J6) in his survey found that the correlation coefficient between icterus index and serum bilirubin concentration was 0.69 in 360 healthy subjects and 0.84 in 40 jaundiced subjects. In newborn infants however, bilirubin is the only yellow pigment likely to be present and the possibility of determining serum bilirubin concentrations by direct measurement has again been re-examined. Abelson and Boggs (Al) diluted serum from infants with erythroblastosis 1 in 50 and studied the absorption curves. They found that in addition to the bili-... 

J6. Josephson, B., The icterus index as a measure of serum bilirubin concentration. Acta Genet. Statist. Med. 4, 231-235 (1953). 

Verdin icterus is deemed to be the prototyp>e of obstructive jaundice, particularly in long-standing courses of the disease melas icterus displays a greyish green hue rubin icterus (rust-coloured) is mainly seen as a sign of hepatocellular jaundice, whereas flavine icterus is more likely to occur in cases of haemolysis (Th. Brugsch, 1930). Such systematization of the icteric forms in terms of pathogenesis is unreliable and obsolete, since the differences in colour mainly correlate with the duration of the jaundice and the level of serum bilirubin. 

Scleral icterus occurs from a serum bilirubin level of 1.6-1.8 mg/dl upwards. At the same time, the conjunctiva is icterially discoloured. Jaundice is based on the affinity of the elastic fibres for bilirubin. 

Under normal conditions, bilirubin is not detectable in the urine. Bilirubinuria may occur in hepatobiliary diseases, with bilirubin regularly appearing in its conjugated (water-soluble) form. Bilirubinuria may be identified prior to the detection of icterus. Jaundice without... 

The term jaundice or icterus is used to depict the yellowish discolouring of the skin, mucous membranes and body fluids witnessed as a result of hyperbilirubinaemia in excess of 2.5 mg/dl, with subsequent deposition of bile pigments in tissue which is rich in elastin. In cases of severely impaired liver function or renal insufficiency, bilirubin values can rise dramatically. The term subicterus is used to describe a low-grade icteric condition occurring in the region of the white sclera with a serum bilirubin value of > 1.8 mg/dl for this reason, it is also known as scleral icterus, (s. pp 80, 99)... 

Kernicterus may occur as the result of immaturity of the blood-brain barrier in severe neonatal icterus and can occasionally be found in premature infants as well, with bilirubin levels usually higher than 20 mg/dl. Unconjugated bilirubin is deposited in the basal ganglia of the hippocampus and the hypothalamus nuclei as bilirubin-phosphatidylcholine precipitate, where it gives rise... 

A 62-year-old woman developed deep icterus and hepatomegaly 1 month after starting to take irbesartan 300 mg/day. She had been hypertensive for 15 years and had no history of hver disease or risk factors for liver disease. Her bilirubin was 403 pmol/1, alkaline phosphatase 3193 IU/1, and aspartate transaminase 177... 

Bilirubin interferes already at low concentrations, and hence samples from patients suffering from jaundice (icterus) are unsuitable for use with these reagent carriers. 

Ingestion of carotenes alone does not cause vitamin A toxicity, probably because of markedly decreased absorption at high doses and feedback inhibition of carotene conversion to retinaldehyde, but can cause harmless carotene-mia with yellowing of the skin, particularly on the palmar and plantar surfaces. Carotenemia can cause falsely elevated values for the icterus index or for other direct reading methods for estimating serum bilirubin (Chapter 29). 

Jaundice (icterus) yeUow coloiuation of the mucous membranes and skin due to an increase in bilirubin. 

Clinical manifestation. It includes the following syndromes a) irritative-pulmotoxic syndrome - with evidence of catarrhal tracheobronchitis, combined with toxic oedema in the severe cases b) cerebral toxic syndrome characterised by ataxia, Menier s syndrome, the severe forms manifest disordered consciousness c) hepatotoxic syndrome - observed in the extremely severe cases of poisoning, manifested as icterus, hepotomegalia and increased blood bilirubin and transaminase values sometimes it is manifested as hepatorenal syndrome d) hemotoxic syndrome - rarely met in acute intoxication by methemoglobinaemia, hemolysis, leukopoenia. 

Creosote Bush. Acute toxic hepatitis has been attributed to ingestion of chaparral, an herbal nutritional supplement product derived from the leaves of the creosote bush (Clark and Reed 1992). A 42-year-old man had icterus and jaundice after consuming three 500 mg capsules of chaparral a day for 6 weeks. Serum chemistry tests showed elevated bilirubin, gamma glutamyltranspeptidase (GGT), AST, and lactate dehydrogenase. His illness was diagnosed as hepatic dysfunction secondary to chaparral ingestion. 

In various liver diseases (jaundice, icterus) excess bilirubin is produced and at the same time the permeability of liver cells to the pigment is increased, so that bilirubin glucuronide ( direet bilirubin ) and bilirubin itself ( indirect bilirubin ) pass into blood and thence diffuse into skin tissue. Obstruction of the bile duct can cause the same symptoms. The determination of bilirubin, therefore, is important clinically. 

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