The substance deposited in skin and sclera in jaundice is?

OSSSC Nursing Officer-2023

Biochemistry & Nutrition

Easy

Appeared in: OSSSC Nursing Officer-2023

Explanation

Jaundice is the yellow discoloration of tissues caused by the deposition of bilirubin.
Unconjugated (indirect) bilirubin is fat-soluble (lipophilic), which allows it to easily cross cell membranes and deposit in tissues like the skin and sclera.
Bilirubin has a high affinity for elastin, a protein abundant in the sclera, which is why scleral icterus is a key sign of jaundice.
Unlike conjugated bilirubin, the unconjugated form cannot be excreted in urine and tends to accumulate in the body when production is high or liver uptake is impaired.

Option B: Direct or conjugated bilirubin is water-soluble. While it causes hyperbilirubinemia in obstructive jaundice, its water solubility allows it to be excreted in urine, making it less prone to depositing in lipid-rich tissues compared to the unconjugated form.
Option C: Biliverdin is the precursor to bilirubin in the heme breakdown pathway. It is not the primary substance that deposits in tissues to cause the classic yellow color of jaundice, although it can contribute a greenish hue in long-standing cases.
Option D: Stercobilin is a pigment derived from bilirubin breakdown in the intestines by bacteria. It is responsible for the brown color of feces and is excreted from the body.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain The concept tested is the pathophysiology of jaundice, specifically identifying the form of bilirubin responsible for tissue deposition as background academic context rather than a clinical decision trigger.
Understanding the difference between conjugated and unconjugated bilirubin is crucial for nurses to interpret lab results and identify the underlying cause of jaundice (e.g., hemolysis vs. liver disease vs. bile duct obstruction).
Scleral icterus is often the first sign of jaundice a nurse will detect during a physical assessment. Its presence warrants reporting and further investigation into liver function.
In neonatal nursing, monitoring for jaundice is critical because high levels of unconjugated bilirubin can cross the blood-brain barrier and cause kernicterus, a form of permanent brain damage.

How to Approach the Question

First, identify the key terms in the question: 'jaundice', 'deposited', 'skin and sclera'. This points to the substance that causes the yellow discoloration.
Recall the basics of bilirubin metabolism. Remember that bilirubin exists in two main forms: unconjugated (indirect) and conjugated (direct).
Consider the chemical properties of each form. Unconjugated bilirubin is fat-soluble, while conjugated bilirubin is water-soluble.
Relate these properties to tissue deposition. Fat-soluble substances can easily cross cell membranes and deposit in fatty tissues and structures like the elastin-rich sclera.
Evaluate the options based on this reasoning. Unconjugated bilirubin's fat-solubility makes it the prime candidate for tissue deposition.
Eliminate the other options by recalling their roles: conjugated bilirubin is excreted, biliverdin is a precursor, and stercobilin is a fecal pigment.

Concept Tested & Keywords

Concept Tested: The concept tested is the pathophysiology of jaundice, specifically identifying the form of bilirubin responsible for tissue deposition.
Stem keywords: jaundice, skin, sclera, deposited
Lead-in keywords: BEST, MOST RELEVANT CLUE

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