Reference Interval:
Less than 1.0%
|
| Interpretive Data: |
a-Thalassemia is caused by underproduction of the a-globin chains that make up hemoglobin molecules. Hb A (a2 b2) and Hb A2 (a2 D2) contain a-chains and therefore are insufficiently produced in a-thalassemia. In this condition, g-globin genes become active early in life, producing homotetramers of g (g4 or Hb Bart). After the first few months of life, when b-chain production is established, homotetramers of b (b4 or Hb H) become predominant. Demonstration of either Hb Bart or Hb H in the blood is proof of reduced a-chain production, and hence a-thalassemia. Accurate genotyping of patients with different amounts of Hb Bart will depend on family studies, hematological parameters, and DNA analysis.
| Patient State
| Newborn Hb Bart Level
| | Normal
| Less than 1%
| | a+ thalassemia
| 1-3%
| | a° thalassemia
| 3-10%
| | Hb H Disease
| 15-30%
| | Hydrops Fetalis
| 80-100%
|
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| CPT Code(s): |
83021
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