Xiao et al reported equations for distinguishing thalassemia traits from iron deficiency anemia using instrumental data. The authors are from Shenzhen Baoan Women's and Children's Hospital and Shenzhen Mindray Bio-Medical Electronic Co, Ltd. in Shenzhen, China.
Patient selection: pregnant woman with microcytic anemia
Parameters:
(1) MCH (mean corpuscular hemoglobin) in pg
(2) percent reticulocytes less than 60 fL in volume
(3) reticulocyte production index (RPI), in the order of 0.8 to 1.3
(4) MCV of mature red blood cells in fL (MCVm)
(5) reticulocyte number in 10^9/L
(6) reticulocyte percent (probably relative to RBC count), in the order of 0.08 to 0.14
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Parameter
|
Value
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MCH
|
0.42 * (MCH)
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|
percent micro-reticulocytes
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0.08 * (percent)
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RPI
|
-0.57 * (RPI)
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|
constant
|
-9.38
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total score 1 for alpha thalassemia trait carrier vs iron deficiency =
= SUM(points for all of the parameters)
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Parameter
|
Value
|
|
MCVm
|
0.12 * (MCVm)
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|
percent micro-reticulocytes
|
0.04 * (percent)
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|
reticulocyte
|
-13.76 * (reticulocytes)
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|
constant
|
-6.29
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total score 2 for beta-thalassemia trait carrier vs iron deficiency =
= SUM(points for all of the parameters)
Interpretation:
• The cut-off for score 1 0.61. Scores above the cut-off indicate iron deficiency.
• The cut-off for score 2: 0.37
Performance:
• For score 1: the area under the ROC curve was 0.87 with Youden index 0.59.
• For score 2: the area under the ROC curve was 0.88 with Youden index 0.63.
NOTE: The second score gives absurd values relative to the cutoff. This most likely is due to the coefficient for the reticulocyte count. Insufficient information is provided to find a better solution.
