Thalassemia Minor (Trait)

Heterozygous Alpha- (α-) or Beta- (β-) Thalassemia Minor (aka Trait)
  • Mediterranean, African, Arabian, South Asian, Asian descent. 
  • Includes all of Latin America and Carribean
Microcytic anemia
  • Hb / Hct around 10 / 30
  • MCV 70-80 for α-Thalassemia, often lower for β-Thalassemia
  • RDW normal
Quantitative Defect
  • Decreased quantities of normal hemoglobins
  • Hemoglobinopathies like sickle cell are “qualitative,” involve abnormal types of Hb (e.g. Hb S, etc).
  • Qualitative defects → Hemolytic anemia (normocytic)
  • Diagnose both by Hemoglobin Electrophoresis

Normal Range of Normal Hemoglobins

•  Hb A (≥97%)           • Hb A2  (<2.5%)           • Hb F (<1%)

Thalassemia Diagnosis by Hemoglobin Electrophoresis

α-Thalassemia Minor

  • Hb A normal  (? ↑)
  • Hb A2 normal  (? <1%)
  • Hb F normal  (? sl ↑)
 β-Thalassemia Minor

  • Hb A ↓  (≤95%)
  • Hb A2 ↑  (≥3%)
  • Hb F normal or ↑
NOTE:  α-Thalassemia often Dx of exclusion (Hb Electrophoresis normal)
  • Mild anemia, MCV 70-79
  • Normal RDW
  • Likely ethnicity
WARNING:  Electrophoresis inaccurate if coexisting Iron Deficiency:
  • Low serum Ferritin = Iron Deficiency
  • Must normalize serum ferritin (iron replacement), then order the electrophoresis

See posting Anemia – 2.