An increase or tendet to increase number of erythrocytes, with low (or very low) MCH (and MCV) with a normal RDW (red distribution width) it is high suspected!
Then proceed to HPLC (but iron deficiency must be discarted)
At our Lab in few hours! At the end of the morning.
Probably the most cost effective method for screening for beta thal trait is by red cell indices (reduced MCV and/or MCH) by electronic hematology counter, and if reduced then we proceed to confirm by Hb A2 estimation. The method for A2 estimation could be HPLC, micocolumn chromatography or elution from cellulose acetate strips. This approach has been adopted by several countries, including Cyprus, Iran and northern Iraq, with excellent results ( al-Allawi et al, 2013, J Med Screen).
We used cheap measurements. First line are MCV, MCH, and RDW. If two of them are under normal value, then check for Hb electrophoresis using HPLC, but we prefer Capillary Electrophoresis (CE) as most convenient for separating Hb.
To screen for beta thal trait reliably, you will need some kind of hemoglobin separation - like HPLC or CE. If your financial resources are restricted, you can start with a full blood count including erythrocyte indices. Thal trait is usually associated with low MCH/MCV, normal RDW and high erythrocytes.
It should also be noted that if the population in question has other Hbpathies like sickle cell disease, Red cell indices and solubility test should done concomitantly.. followed by HPLC or CE to confirm.