Red Cell Indices and Therapeutic Trial of Iron in Diag
nostic Work-Up for Anemic Thai Females
ISSARANG NUCHPRA YOON, MD, PhD, F AAP*,
BOONRUEN SUKTHA WEE, BNS**,
THASSANEE NUCHPRA YOON, MD, DTM&H, MPH**
Affiliation : * Department of Pediatrics,
** Department of Preventive and Social Medicine, Faculty of Medicine, Chulalongkom University, Bangkok 10330,
Thailand.
AbstractAnemia is common among Thai females. Thalassemia and iron deficiency are highly pre
valent in the Thai population. A therapeutic trial of iron has been used to differentiate between the two
conditions, however, no previous study on its usefulness in a Thai population has been reported.
Otherwise healthy persons who had complete blood count (CBC) as routine 'check-up' and found to
be anemic (Hb < 12 g/dl) at a preventive medicine clinic were tested for hemoglobin typing, serum
ferritin, serum iron, and were given oral iron sulfate (120 mg elemental iron per day for at least 2
months) and a repeat CBC on a follow-up visit. Sixty-six individuals, all females, with pre-treatment
hemoglobin (Hb) level of 9.5 ± 1.7 g/dl (mean± SD), had complete data for analysis. Final diagnoses
were isolated iron deficiency in 23 (34.8% ), iron deficient thalassemia traits in 6 (9.1%) and iron
sufficient thalassemia syndromes in 29 (43.9%) anemic subjects. After a therapeutic trial of iron, Hb
rose to 12.8 ± 1.0 g/dl (n = 16, p = 2 x 10·8) among the iron deficient group, but not in thalassemia. The
authors have identified that the most useful red cell indices that will discriminate between iron defi
ciency and thalassemia is a combination of red blood cell counts (RBC) > 4.4 x l06/J..l1 and mean corpus
cular volume (MCV) < 69 fl. High RBC (> 4.4 x 106/J..ll) and very low MCV (< 69 fl) is a sensitive
(92.9%) and highly specific ( 100%) criteria for diagnosis of mild thalassemia diseases (Hemoglobin H
(HbH), Hemoglobin H-Constant Spring (HbH-CS), and homozygous Hemoglobin E (HbEE)). Con
versely, a low RBC (> 4.4 x 106/J..ll) and/or low to normal MCV (69-85 fl) is highly sensitive (91.3%)
but not specific (60%) for the diagnosis of iron deficiency. The authors conclude that a therapeutic trial
of iron is useful as a diagnostic test in anemic females except those with high RBC (> 4.4 x 106/J..1.1)
and very low MCV (< 69 fl), a subgroup which most likely has thalassemia and are least likely to benefit
from iron treatment.
Keywords : Anemia, Red Cell Indices, Iron Deficiency, Thalassemia, Therapeutic Trial of Iron
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