Jaundice syndrome in infectious diseases: causes and diagnosis

The deposition of bilirubin in tissues due to a violation of the dynamic balance between the rate of its formation and excretion leads to yellow staining of the skin, mucous membranes and sclera.

Jaundice syndrome, also known as Gospell's disease, has an extremely important clinical and diagnostic value in many diseases, especially infectious diseases.

This article on estet-portal.com describes the causes of jaundice, as well as laboratory signs that play a key role in the differential diagnosis of jaundice.

Classification of jaundice syndrome and principles of laboratory diagnostics

There are several classifications of jaundice syndrome.

According to the mechanism of development, they are distinguished:

1.    Suprahepatic jaundice;

2.    Hepatic (parenchymal) jaundice;

3.    Subhepatic (mechanical, obstructive) jaundice.

According to the severity of jaundice syndrome, there are such forms as:

1.    mild jaundice (total serum bilirubin does not exceed 85 µmol/l);

2.    moderate jaundice (total serum bilirubin in the range of 86-170 µmol/l)

3.    severe jaundice (total serum bilirubin exceeds 170µmol/l).

In addition, there are acute (up to 3 months), protracted (3-6 months) and chronic (over 6 months) forms of jaundice syndrome.

Jaundice occurs when the concentration of bilirubin in the blood exceeds 40 µmol/l. First of all, yellowing of the sclera and mucous membranes occurs, skin staining occurs later.

Patients with jaundice syndrome should undergo the following tests: complete blood count, general urinalysis, biochemical blood test (prothrombin index, cholesterol, total protein, protein fractions, ALT, AST, GGT, LF), blood test for viral markers: HAV, HBV, HCV, HDV, HEV.

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Causes of jaundice: what leads to the development of suprahepatic form

The most common cause of suprahepatic jaundice is hemolysis of red blood cells, which leads to a significant increase in the formation of bilirubin. In addition, this condition may be due to impaired binding of bilirubin to albumin and its subsequent transport to hepatocytes.

The reason for the development of suprahepatic jaundice may also be a violation of the process of conjugation of bilirubin in hepatocytes.

In most cases, the diagnosis of suprahepatic jaundice is not difficult.

This condition is characterized by the following laboratory findings:

1.    increase in total bilirubin mainly due to the indirect fraction;

2.    signs of hemolytic anemia (decreased hemoglobin levels, reticulocytosis, decreased osmotic resistance of erythrocytes and haptoglobin), if it is the cause.

In hemolytic anemia, which leads to the development of suprahepatic jaundice, a high level of urobilin is detected in the general urine test.

Diarrhea and exanthema may be symptoms of enterovirus infection

Causes of jaundice: pathogenesis of the parenchymal form of the syndrome

In the pathogenesis of the development of parenchymal jaundice, the key role belongs to the destruction of hepatocytes, which leads to an increase in the level of total bilirubin, mainly due to the direct fraction.

Simultaneously with an increase in the level of direct bilirubin in the blood, its excretion with bile worsens. This causes the feces to become hypocholic. Urine, on the contrary, darkens, which is associated with an increase in the content of bile pigments (direct bilirubin) in it.

Other characteristic laboratory findings of hepatic jaundice are:

1.    an increase in the level of transaminases mainly due to ALT (alanine aminotransferase);

2.    decrease in albumin levels due to inhibition of the protein-synthetic function of the liver.

For more information on what infections lead to the development of parenchymal jaundice, read on.

See also: Infectious mononucleosis: modern methods of diagnosing the disease

Subhepatic jaundice occurs due to impaired bile excretion

The reason for the development of subhepatic jaundice is a violation of the secretion of bile into the duodenum due to obstruction of the biliary tract by stones, postoperative narrowing of the bile duct, compression of the common bile duct of the head pancreas, etc. This leads to the fact that bile does not enter the intestine and, as a result, the formation of stercobilin and urobilin does not occur.  

In subhepatic jaundice, the feces become acholic and the urine becomes orange-brown due to bile pigments. This type of jaundice is often accompanied by pruritus associated with cholestasis.

Among the laboratory signs that indicate subhepatic jaundice, it is necessary to highlight the increase in the levels of GGTP (Gamma-glutamyl transpeptidase), ALP (alkaline phosphatase) and conjugated bile acids. There may also be an increase in transaminases, but much less significantly than with parenchymal jaundice.

What infections can be accompanied by the development of jaundice syndrome

Jaundice as a manifestation of infection most often results from direct damage to the liver by an infectious pathogen. Hepatic jaundice accompanies such infectious diseases as icteric forms of viral hepatitis (A, B, C, D and E), acute viral hepatitis of mixed etiology (B and D), infectious mononucleosis (in 10% of cases).

Jaundice accompanies such infectious diseases as icteric forms of viral hepatitis (A, B, C, D and E), acute viral hepatitis of mixed etiology (B and D), infectious mononucleosis (10% of cases), as well as some helminthiases, protozooses and spirochetoses.

Bright jaundice against the background of fever accompanies leptospirosis (in such cases, kidney damage and hemorrhagic syndrome also occur), malaria (a typical temperature curve is characteristic).

Among the helminthiases, for which the nature of jaundice, should be distinguished echinococcosis, alveococcosis, fascioliasis, clonorchiasis, toxocariasis and schistosomiasis.

Of course, the above diseases are far from exhausting the entire list of nosologies in which icteric syndrome can occur. At the same time, it should be remembered that jaundice – this is an isolated syndrome, which must be considered only in conjunction with the patient's complaints, his epidemiological history, objective examination data and the results of additional research methods.

Thank you for staying with estet-portal.com. Read other interesting articles in the "Infectology" section. You might also be interested in: Are Dirty Hands to Blame: A Modern Perspective on Viral Hepatitis.