Jaundice
65980
223795860
2008-07-05T21:13:49Z
24.84.207.10
{{Expand|date=May 2007}}
{{wiktionary|jaundice}}
{{DiseaseDisorder infobox |
Name = Jaundice, NOS |
Image = PHIL 2860 lores.jpg|
Caption = Yellowing of the [[skin]] and [[sclera]] caused by [[Hepatitis|Hepatitis A]].|
ICD10 = {{ICD10|R|17||r|10}} |
ICD9 = {{ICD9|782.4}} |
OMIM = |
MedlinePlus = 003243 |
eMedicineSubj = |
eMedicineTopic = |
DiseasesDB = 7038 |
MeshID = D007565 |
}}
'''Jaundice''', also known as '''icterus''' (attributive adjective: "icteric"), is yellowish discoloration of the [[skin]], [[sclera|sclerae]] (whites of the eyes) and [[mucous membrane]]s caused by hyperbilirubinemia (increased levels of [[bilirubin]] in the blood). This hyperbilirubinemia subsequently causes increased levels of [[bilirubin]] in the extracellular fluids. Typically, the concentration of bilirubin in the [[Blood plasma|plasma]] must exceed 1.5 [[milligram|mg]]/[[decilitre|dL]]<ref name="MedPhy">{{cite book
| last = Guyton
| first = Arthur
| coauthors = Hall, John
| title = Textbook of Medical Physiology
| publisher = Saunders
| date = September 2005
| isbn = 978-0721602400}}</ref>, three times the usual value of approximately 0.5[[milligram|mg]]/[[decilitre|dL]]<ref name="MedPhy" />, for the coloration to be easily visible. ''Jaundice'' comes from the [[French language|French]] word ''jaune'', meaning yellow.
==Normal Physiology==
In order to understand how jaundice results, it is important to understand where the pathological processes that cause jaundice take their effect. It is also important to further recognize that jaundice itself is not a disease, but rather a symptom of an underlying pathological process that occurs at some point along the normal physiological pathway of the metabolism of bilirubin.
===Pre-hepatic events===
When [[red blood cell]]s have completed their life span of approximately 120 days, their membranes become fragile and prone to rupture. As the cell traverses through the [[reticuloendothelial system]], their cell membranes rupture and the contents of the red blood cell is released into the blood. The component of the red blood cell that is involved in jaundice is [[hemoglobin]]. The hemoglobin released into the blood is phagocytosed by [[macrophages]], and split into its [[heme]] and [[globin]] portions. The globin portion, being [[protein]], is degraded into [[amino acids]] and plays no further role in jaundice. Two reactions then take place to the heme molecule. The first reaction is the [[oxidation]] of heme to form [[biliverdin]].This reaction is catalyzed by microsomal enzyme heme oxygenase and it results in biliverdin (green color pigment), iron and carbon monoxide. Next step is reduction of biliverdin to yellow color tetrapyrol pigment bilirubin by cytosolic enzyme biliverdin reductase. This bilirubin is known as "unconjugated", "free" or "indirect" bilirubin. Approximately 4 mg per kg of bilirubin is produced each day.<ref name="PedRev">{{cite journal
| last = Pashankar
| first = D
| coauthors = Schreiber, RA
| title = Jaundice in older children and adolescents
| journal = Pediatrics in Review
| volume = 22
| issue = 7
| pages = 219–226
| date = July 2001
| doi = 10.1542/pir.22-7-219
| pmid = 11435623}}</ref> The majority of this bilirubin comes from the breakdown of heme from expired red blood cells in the process just described. However approximately 20 per cent comes from other heme sources, including ineffective erythropoiesis, breakdown of other heme protrins such as muscle myoglobin and cytochrome enzymes.<ref name="PedRev" />
===Hepatic events===
The unconjugated bilirubin then travels to the [[liver]] through the bloodstream. Because this bilirubin is not soluble, however, it is transported through the blood bound to [[serum albumin]]. Once it arrives at the liver, it is conjugated with [[glucuronic acid]] (to form bilirubin diglucuronide, or just "conjugated bilirubin") to become more water soluble. The reaction is catalyzed by the enzyme UDP-glucuronide transferase.
===Post-hepatic events===
This conjugated bilirubin is excreted from the liver into the biliary and cystic ducts as part of [[bile]]. Intestinal bacteria convert the bilirubin into [[urobilinogen]]. From here the urobilinogen can take two pathways. It can either be further converted into [[stercobilinogen]], which is then [[oxidized]] to [[stercobilin]] and passed out in the [[faeces]], or it can be reabsorbed by the intestinal cells, transported in the blood to the [[kidneys]], and passed out in the [[urine]] as the oxidised product [[urobilin]]. Stercobilin and urobilin are the products responsible for the coloration of faeces and urine, respectively.
==Causes==
When a pathological process interferes with the normal functioning of the metabolism and excretion of bilirubin just described, jaundice may be the result. Jaundice is classified into three categories, depending on which part of the physiological mechanism the pathology affects. The three categories are:
* '''Pre-hepatic''': The pathology is occurring prior the liver
* '''Hepatic''': The pathology is located within the liver
* '''Post-Hepatic''': The pathology is located after the conjugation of bilirubin in the liver
===Pre-hepatic===
'''Pre-hepatic''' jaundice is caused by anything which causes an increased rate of [[hemolysis]] (breakdown of [[red blood cell]]s). In tropical countries, [[malaria]] can cause jaundice in this manner. Certain [[Genetic disorder|genetic diseases]], such as [[sickle cell anemia]], [[spherocytosis]] and [[glucose 6-phosphate dehydrogenase deficiency]] can lead to increased red cell lysis and therefore hemolytic jaundice. Commonly, diseases of the kidney, such as [[hemolytic uremic syndrome]], can also lead to coloration. Defects in [[bilirubin metabolism]] also present as jaundice. Jaundice usually comes with high fevers.
'''Laboratory findings''' include:
* Urine: no bilirubin present, urobilirubin > 2 units (except in infants where [[gut flora]] has not developed).
* Serum: increased unconjugated bilirubin.
===Hepatic===
'''Hepatic''' jaundice causes include acute [[hepatitis]], [[hepatotoxicity]] and [[alcoholic liver disease]], whereby cell necrosis reduces the liver's ability to metabolise and excrete [[bilirubin]] leading to a buildup in the blood. Less common causes include [[primary biliary cirrhosis]], [[Gilbert's syndrome]] (a genetic disorder of bilirubin metabolism which can result in mild jaundice, which is found in about 5% of the population), [[Crigler-Najjar syndrome]] and [[metastasis|metastatic]] [[carcinoma]]. Jaundice seen in the newborn, known as neonatal jaundice, is common, occurring in almost every newborn as [[hepatic]] machinery for the conjugation and excretion of bilirubin does not fully mature until approximately two weeks of age.
'''Laboratory Findings''' include:
* Urine: Conjugated bilirubin present, Urobilirubin > 2 units but variable (Except in children)
===Post-hepatic===
'''Post-hepatic''' jaundice, also called obstructive jaundice, is caused by an interruption to the drainage of [[bile]] in the biliary system. The most common causes are [[gallstone]]s in the [[common bile duct]], and [[pancreatic cancer]] in the head of the [[pancreas]]. Also, a group of parasites known as "[[liver fluke]]s" live in the common bile duct, causing obstructive jaundice. Other causes include strictures of the common bile duct, [[biliary atresia]], [[ductal carcinoma]], [[pancreatitis]] and [[pancreatic pseudocyst]]s. A rare cause of obstructive jaundice is [[Mirizzi's syndrome]].
The presence of pale stools and dark urine suggests an obstructive or post-hepatic cause as normal feces get their color from [[bile pigment]]s.
Patients also can present with elevated serum cholesterol, and often complain of severe itching or "pruritus".
===Laboratory Tests===
No one test can differentiate between various classifications of jaundice.A combinations of liver function tests is essential to arrive at a diagnosis.
{| class="wikitable"
|-
!
! Pre-hepatic Jaundice
! Hepatic Jaundice
! Post-hepatic Jaundice
|-
! Total bilirubin
| Normal / Increased
| Increased
| Increased
|-
! Conjugated bilirubin
| Normal
| Normal / Decreased
| Increased
|-
! Unconjugated bilirubin
| Increased
| Normal / Increased
| Normal
|-
! Urobilinogen
| Increased
| Normal / Increased
| Decreased / Negative
|-
! Urine Colour
| Normal
| Dark
| Dark
|-
! Stool colour
| Normal
| Normal
| Pale
|-
! Alkaline phosphate levels
| normal
| normal
| increased
|-
! Alanine transferase n Aspartate transferase levels
| normal
| increased
| normal
|}
==Neonatal jaundice==
{{main|Neonatal jaundice}}
'''Neonatal jaundice''' is usually harmless: this condition is often seen in [[infants]] around the second day after birth, lasting until day 8 in normal births, or to around day 14 in [[premature birth]]s. Serum [[bilirubin]] normally drops to a low level without any intervention required: the jaundice is presumably a consequence of metabolic and physiological adjustments after birth. In extreme cases, a brain-damaging condition known as [[kernicterus]] can occur; there are concerns that this condition has been rising in recent years due to inadequate detection and treatment of neonatal hyperbilirubinemia. Neonatal jaundice is a risk factor for hearing loss.<ref>{{cite journal
| last = O'Keefe
| first = Lori
| title = Increased vigilance needed to prevent kernicterus in newborns
| journal = American Academy of Pediatrics
| volume = 18
| issue = 5
| pages = 231
| publisher =
| location =
| date = 2001-05-05
| url = http://aapnews.aappublications.org/cgi/content/full/18/5/231
| doi =
| id =
| accessdate = 2007-06-27}}</ref>
==Jaundiced eye==
It was once believed persons suffering from the medical condition jaundice saw everything as yellow. By extension, the jaundiced eye came to mean a prejudiced view, usually rather negative or critical. [[Alexander Pope]], in 'An Essay on Criticism' (1711), wrote: "All seems infected that the infected spy, As all looks yellow to the jaundiced eye."<ref name=eye>From "The Dictionary of Cliches" by James Rogers (Ballantine Books, New York, 1985).</ref> Similarly in the mid 19th century the English poet Lord [[Alfred Tennyson]] wrote in the poem 'Locksley Hall': "So I triumphe'd ere my passion sweeping thro' me left me dry, left me with the palsied heart, and left me with a jaundiced eye."
==External links==
*[http://www.childliverdisease.org/education/yellowalert Children's Liver Disease Foundation: information on jaundice in infants]
==See also==
*[[Cholestasis]]
*[[Neonatal jaundice]]
==Footnotes==
{{reflist}}
{{Digestive system and abdomen symptoms and signs}}
[[Category:Diseases]]
[[Category:Digestive system]]
[[Category:Gastroenterology]]
[[Category:Hepatology]]
[[ar:يرقان]]
[[bs:Žutica]]
[[bg:Жълтеница]]
[[ca:Icterícia]]
[[cs:Žloutenka]]
[[da:Gulsot]]
[[de:Ikterus]]
[[es:Ictericia]]
[[eo:Iktero]]
[[fr:Ictère]]
[[hr:Žutica]]
[[it:Ittero]]
[[he:צהבת]]
[[la:Icterus]]
[[lt:Gelta]]
[[ml:മഞ്ഞപ്പിത്തം]]
[[ms:Demam kuning jaundis]]
[[nl:Geelzucht]]
[[ja:黄疸]]
[[no:Gulsott]]
[[nn:Gulsot]]
[[pl:Żółtaczka (medycyna)]]
[[pt:Icterícia]]
[[sq:Verdhëza]]
[[simple:Jaundice]]
[[sk:Žltačka]]
[[sl:Zlatenica]]
[[fi:Keltaisuus]]
[[sv:Gulsot]]
[[te:పచ్చకామెర్లు]]
[[vi:Hoàng đản]]
[[tr:Sarılık]]
[[zh:黄疸]]