Haemoglobin electrophoresis

The expected result is a normal adult pattern (haemoglobin A with a small amount of A2 and F); the report usually names any variant found, such as sickle trait or beta thalassaemia trait.

This test separates the different types of haemoglobin in the blood so that each can be identified and measured. Modern laboratories usually do it by a method called HPLC or capillary electrophoresis, but the older name has stuck. It is the definitive way to find inherited haemoglobin variants such as sickle haemoglobin and the thalassaemias.

Doctors request it when the red cells are small with normal iron, in antenatal screening so that both parents' status is known before a baby is born, when a sickle screen is positive, and when a family member has a known haemoglobin condition.

• Sickle cell trait or disease
• Beta thalassaemia trait or disease
• Haemoglobin C, D, E and other variants, each common in particular parts of the world
• Inherited persistence of fetal haemoglobin

• A normal pattern means no variant was found; some alpha thalassaemia traits give a normal pattern and are picked up from the red cell indices instead

• A recent blood transfusion can hide a variant or introduce one from the donor for a few months
• Low iron lowers the HbA2 and can hide beta thalassaemia trait until the iron is corrected
• Many variants found are carrier states that cause no ill health; the report will say

No fasting needed. Best done when iron stores are normal and at least three months after any blood transfusion. Usually a once-only test, because the pattern is inherited and does not change.

Written by a UK consultant physician. Typical UK adult reference ranges; your laboratory's own printed range takes precedence.