Inaccuracy of high-performance liquid chromatography estimation of haemoglobin F in the presence of increased haemoglobin A1c.

Increasingly high-performance liquid chromatography is being used for identification and quantification of normal and variant haemoglobins. In many laboratories, the Beta Thal Short programme of the Bio-Rad Variant II instrument is used for this purpose. We noted that a factitious elevation of haemoglobin F was sometimes observed in diabetic patients and therefore carried out a systematic study of this phenomenon. We found discrepant results in 41% of samples from diabetic patients but in no normal volunteers. This factitious elevation could be predicted from a retention time for haemoglobin F of more than 1.15 min, the normal retention time being 1.08-1.15 min. Haemoglobinopathy laboratories need to be alert to the possibility of this erroneous result.