Can normal MCV screening exclude thalassemia?

Normal average red blood cell volume in screening for thalassemia usually cannot completely rule out thalassemia, and requires comprehensive judgment based on other indicators. The screening for thalassemia is mainly based on indicators such as average red blood cell volume, hemoglobin electrophoresis, and genetic testing. If the average red blood cell volume is normal, there may be a risk of misdiagnosis for mild or quiescent thalassemia. The average red blood cell volume (SEP) is an indicator reflecting the size of red blood cells, with a normal range of 80-100 liters. Some patients with mild alpha or beta thalassemia may present with normal or mild decrease in mean red blood cell volume, especially when combined with iron deficiency anemia, which may result in pseudo normalization of indicators. Hemoglobin electrophoresis can detect abnormal hemoglobin bands, which have high diagnostic value for beta thalassemia. However, some alpha thalassemia variants may show normal electrophoresis results. Genetic testing is the gold standard for diagnosis, capable of identifying stationary or rare mutation types that are difficult to detect through routine screening.

Static alpha thalassemia gene carriers usually have no clinical symptoms, and their average red blood cell volume and hemoglobin electrophoresis are normal. Only through genetic testing can alpha gene deficiency be detected. Some non deletion mutations or compound heterozygous mutations may cause intermediate Mediterranean anemia, with mild clinical manifestations but below the diagnostic threshold for mean red blood cell volume. When combined with vitamin B12 or folate deficiency, large cell anemia may mask the typical small cell changes of thalassemia, resulting in false negatives in screening.

It is recommended that individuals with a family history or suspected symptoms undergo complete hemoglobin electrophoresis and genetic testing even if their average red blood cell volume is normal. The critical value of average red blood cell volume detected during pregnancy screening should alert couples to the risk of both being carriers, and genetic counseling should be sought if necessary. Pay attention to daily observation of anemia symptoms such as fatigue and pale complexion, and avoid blindly supplementing iron to interfere with diagnosis. Confirmed patients should regularly monitor their iron metabolism indicators to prevent the occurrence of secondary hemochromatosis.