Thalassemia Lab Diagnosis

2 min read

INTRODUCTION

Thalassemias are inherited red blood cell disorders caused by mutations in the alpha or beta globin gene clusters, leading to reduced production of hemoglobin tetramer. This results in anemia due to decreased synthesis of normal adult hemoglobin.

Test Catageory
فئة التحليل

Hematology

Refrence Books
كتب مراجع

1. Daice & Lewis Practical Hematology
2. Hofbrand’s Essential Hematology

Skills Required
المهارات المطلوبة

1. Microscopy
2. Good Interpretation

Video Resources
مصادر فيديو

عربي
English

Etiology (Causes)

It is inherited in an autosomal recessive pattern. Both parents must be carriers for the child to inherit thalassemia major.
Alpha thalassemia is caused by mutations in one or more of the 4 Alpha globin genes located on chromosome 16. This leads to reduced alpha globin production.
Beta thalassemia occurs from mutations in the Beta globin gene on chromosome 11. This causes deficient beta globin synthesis.

Pathophysiology

Thalassemia occurs due to mutations in alpha or beta globin genes, leading to reduced synthesis of the corresponding globin protein. This causes imbalance in the alpha:beta globin chain ratio required to form normal adult hemoglobin tetramers. The excess unmatched globin chains are unstable and precipitate inside red cell precursors, causing ineffective erythropoiesis, hemolysis, and anemia. Oxidative damage also contributes to shortened red cell survival.

Sample Type

1. Peripheral blood collected in EDTA for complete blood count and peripheral smear (PBP)

Tests Required to Diagnose Thalassemia

Complete Blood Count:
1. Perform automated CBC
2. Note red cell parameters – low MCV and MCH typical
3. Examine peripheral smear for hypochromia, microcytosis, target cells
Hemoglobin Electrophoresis:
1. Use alkaline electrophoresis to separate hemoglobin types
2. Determine presence and relative quantity of HbF, HbA, HbA2
Additional Tests:
1. Iron studies to exclude iron deficiency
2. Hb H inclusion bodies for alpha thalassemia
3. DNA mutational analysis for definitive diagnosis

Result Interpretation

Interpretation for Beta Thalassemia:
1. Hb F and Hb A2 elevated
2. Hb A decreased
3. Genetic testing confirms beta globin gene mutation
Interpretation for Alpha Thalassemia:
1. Hb Barts present in alpha thalassemia major
2. DNA analysis detects alpha globin gene defects