Distinguishing iron deficiency anemia from thalassemia by the red blood cell lifespan with a simple CO breath test: a pilot study

Background: Extant indices for distinguishing between iron deficiency anemia (IDA) and thalassemia (Thal) have substantial practical limitations. The aim of this pilot study was to assess the predictive value of red blood cell lifespan (RBCLS), as determined by an automated CO breath test analysis approach, in the differential diagnosis of these two common forms of microcytic hypochromic anemia (MHA). Methods: RBCLS measurements were conducted in 35 healthy controls (HCs) and 114 patients diagnosed with MHA (IDA, N = 59; and Thal, N = 55) with ELS TESTER that provides a direct RBCLS value read-out. RBCLS between IDA and Thal was compared and evaluated by referring to normal cut-off from the instrument. Results: Compared with that in HCs, RBCLS in IDA and Thal groups was shortened; and median RBCLS was shorter in the Thal group than that in IDA group (33 d versus 79 d, p < 0.001). The median RBCLS in IDA patients with chronic gastrointestinal (GI) bleeding was shorter than that those without GI bleeding (38 d versus 100 d, p < 0.001). Using 75 d as a cut-off, RBCLS had a sensitivity of 96.4% and a specificity of 50.8% for detecting Thal. When GI bleeding patients were excluded from the IDA group, discriminant efficiency of RBCLS was further improved. Conclusions: MHA with a normal RBCLS is suggestive of IDA, whereas MHA with a significantly shortened RBCLS without signs of chronic GI bleeding is suggestive of Thal.