Screening for Hemoglobinopathies in Pediatric Practice
By Beth A. Pletcher, MD, May 1998

Hemoglobin screening poses a problem for many pediatricians because of the nuances of testing and various hemoglobin variants found in different populations. Although many practitioners recognize the risks for sickle cell trait in the black population and risks for thalassemia minor in the Mediterranean population, it is important to screen Hispanic patients for both and black patients for thal minor since these are quite prevalent in these populations as well.

If a patient has microcytosis (MCV <80), additional testing should be pursued.

The Mentzer Index is sometimes helpful in differentiating thal trait from iron deficiency as is the RDW.

Mentzer Index=MCV / RBC

if <13

suggests possible thal trait

if >14

suggests possible iron deficiency

RDW

if <19

possible thal trait

if >19

possible iron deficiency

Determine MCV

if low

do quantitative HGB A2, HGB F, ferritin and lead, FEP and TIBC

if normal

no more studies

HGB A2 NL=<3.6% HGB F NL=<2.5%

Differential diagnoses

A2

F

ferritin

TIBC

MCV

FEP

Iron deficiency

nl

nl

low

high

low

high

Chronic anemia

nl

nl

low

nl

low

high

b- thal trait

high A2

+/- F

nl

nl

low

nl

thal trait

nl

nl

nl

nl

low

nl

Lead poisoning

nl

nl

nl

nl

low

high