Definition of Icterus
Icterus is the yellowish discoloration of skin and mucous membrane and body fluids (CSF, joint fluid, cysts) evident as a result of hyperbilirubinemia with subsequent deposition of bile pigments in tissue which is rich in elastin. The Greeks claimed the sight of an oriole would cure jaundice, thus they got a name i.e. icterus (Greek- Ikteros). Usually, jaundice becomes apparent clinically as icterus at serum bilirubin levels exceeding 2-3 mg/dl in older children and adults and at more than 5 mg/dl in neonates.
Sites to look for Icterus
Pre-requisite: Preferably natural daylight (may not be detected in artificial light). Use transcutaneous bilirubinometer in infants if natural light is not available.
- Upper bulbar conjunctiva (sclera)
- Under surface of tongue
- Palms and soles
- General skin surface
In fair-skinned individulas, it is most noticeable on face, trunk and sclera while in those with darker complexion it is best evident on palate, sclera and conjunctiva.
Assessment of icterus in Upper bulbar conjunctiva
How (technique)? Retract both the upper eyelids simultaneously upward and ask the patient to look downwards.
Why (reason)? Actually, it is not in the bulbar conjunctiva that we are trying to look for. It is the white background of sclera behind the transparent conjunctiva. Sclera is rich in elastin and bilirubin has a strong affinity to elastic tissue.
Assessment of icterus in Neonates
How? Press the skin against bony surface for 5 seconds to blanch the skin and observe the skin color. Gently press over forehead or chest.
Why? To press out the normal pink or brown color so that the yellowish blanching can be noted.
Kramer’s rule: Kramer recognised the cephalocaudal progression of jaundice with increasing total serum bilirubin levels and divided the baby into 5 zones, with an estimated total serum bilirubin level measurement associated with each zone.
- Grade 1 (Face and neck only): 10 mg/dl
- Grade 2 (Upper trunk upto umbilicus): 15 mg/dl
- Grade 3 (Lower trunk below umbilicus to knee): 20 mg/dl
- Grade 4 (Arms and lower legs below knee): 25 mg/dl
- Grade 5 (Palms and soles): >25 mg/dl
Shades/Colors of Jaundice
- Reddish shade (Rubin jaundice): Hepatitis
- Lemon yellow with a reddish hue (Flavin jaundice): Hemolysis
- Greenish yellow (Verdin jaundice): Obstructive jaundice
- Grayish or blackish green (Melas jaundice): Prolonged obstructive jaundice
Differential diagnosis of Jaundice
Jaundice is the only condition causing yellow sclerae. Other causes of yellow discoloration of the skin, but where the sclera remain normal are:
- Carotenaemia/Xanthoderma: Usually due to excessive consumption of carotene – carrots and mangoes
- Lycopenaemia: Excessive consumption of tomatoes
- Picric acid ingestion
- Drugs: Quinarcine (Atabrine, Mepacrine), Busulfan
Tips for aid of Diagnosis
Look for other signs that helps in diagnosis.
- Spider nevi, gynecomastica, white nails, palmar erythema, dupyutren’s contracture: Cirrchosis
- Ascites, splenomegaly, dilated abdominal wall veins, periumbilical venous hum: Portal hypertension
- Kayer-Fleischer ring and neuropsychiatric changes: Wilson’s disease
- Gray pigmentation: Hemochromatosis
- Excoriations and xanthomas: Primary biliary cirrhosis
- Severe left-or right-sided heart failure: Passive congestion or hepatocellular ischemia
- Palpable non-tender gallbladder: Pancreatic carcinoma (Courvoiser’s law)
Difference between Icterus and Jaundice
While both the terms are used synonyms, some authors use “jaundice” for yellowish discoloration of skin and “icterus” as that of sclera.