Understanding Red Blood Cell Fragility & Hemolysis – A Complete Guide

1. What is Hemolysis?

  • Hemolysis means the destruction or rupture of red blood cells (RBCs).
  • When RBCs burst, hemoglobin is released into the blood plasma.
  • Can happen inside the body (intravascular) or outside (during lab testing).

Mnemonic: “He-MO-Lysis” = Hemoglobin Moves Out due to Lysis


2. Types of Hemolysis

Type

Where it Happens

Example

Intravascular

Inside blood vessels

Mismatched blood transfusion

Extravascular

In spleen/liver

Autoimmune hemolytic anemia

In vitro

Outside body (in lab)

Improper blood sample handling

3. Causes of Hemolysis

Mnemonic: “SHIRT”

  • S – Sickle Cell Anemia
  • H – Hereditary Spherocytosis
  • I – Infections (like malaria)
  • R – Reactions (transfusion mismatches)
  • T – Toxins & Drugs (e.g., snake venom, sulfa drugs)

4. Effects of Hemolysis

  • Hemoglobinemia – Free Hb in blood
  • Hemoglobinuria – Hb in urine
  • Jaundice – ↑ Unconjugated bilirubin
  • Anemia – Due to RBC destruction
  • Splenomegaly – If extravascular

Mnemonic: “HAJHS”
Hemoglobinemia, Anemia, Jaundice, Hemoglobinuria, Splenomegaly


5. Lab Hemolysis (In vitro)

  • Happens outside the body, often due to:
    • Shaking blood sample
    • Using a small needle
    • Drawing blood too fast
  • Causes false test results like falsely low potassium or calcium.

6. What is Fragility of RBCs?

  • Refers to the sensitivity of RBCs to break down in a hypotonic (diluted salt) solution.
  • Osmotic Fragility Test is used to check how easily RBCs rupture.

7. Osmotic Fragility Test

  • RBCs placed in decreasing concentrations of NaCl (salt) solution.
  • Normal RBCs start hemolysis at 0.48% NaCl and complete at 0.36%.
  • If RBCs are more fragile, they burst earlier (e.g., spherocytosis).
  • If less fragile, they resist bursting (e.g., thalassemia, sickle cell).

 Mnemonic: “SALTY Cells BURST”


8. Osmotic Fragility in Diseases

Disease

Fragility Status

Hereditary spherocytosis

Increased (burst early)

Thalassemia

Decreased (burst late)

Sickle cell anemia

Decreased

Normal

Standard range

9. Why Does Fragility Change?

  • Depends on the structure and flexibility of the RBC membrane.
  • If RBCs are rigid or misshapen, they rupture easily.
  • If RBCs are flexible or thin, they resist bursting.

10. Uses of Osmotic Fragility Test

  • Diagnose hereditary spherocytosis
  • Differentiate types of anemia
  • Check membrane integrity of RBCs

Quick Mnemonics Recap:

Concept

Mnemonic

Causes of Hemolysis

SHIRT

Effects of Hemolysis

HAJHS

Fragility Test Idea

SALTY Cells BURST

Hemolysis Meaning

He-MO-Lysis

FAQs – Frequently Asked Questions

Q1. What is hemolysis?

Ans: Hemolysis is the breaking of red blood cells leading to the release of hemoglobin into the plasma.

Q2. What causes hemolysis?

Ans: Causes include sickle cell anemia, hereditary spherocytosis, mismatched blood transfusion, malaria, and certain toxins or drugs.

Q3. What is osmotic fragility?

Ans: Osmotic fragility refers to the ability of RBCs to withstand bursting in hypotonic (dilute salt) solution.

Q4. Which condition shows increased osmotic fragility?

Ans: Hereditary spherocytosis shows increased fragility (RBCs rupture early in dilute solution).

Q5. What happens to plasma in hemolysis?

Ans: Plasma becomes pink or red due to the presence of free hemoglobin.

Q6. What is the significance of the osmotic fragility test?

Ans: It helps diagnose RBC membrane disorders like hereditary spherocytosis and differentiate between types of anemia.



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