Betke's and elution methods in estimation of haemoglobin F in sickle cell anaemia.

OBJECTIVE

To compare the effect of the type of spectrophotometer and method used in the estimation of HbF.

DESIGN

Two sets of experiments were done. In the first set, paired blood samples were obtained from 28 adult sickle cell anaemia subjects. One of each pair of samples was analysed for HbF by Betke's method and the other by the elution method and the values obtained were compared. In the second set of experiments, ten other paired samples were analysed for HbF, one using an analogue spectrophotometer and the other using a digital spectrophotometer and the results compared.

SETTING

Adult sickle cell clinic, University College Hospital, Ibadan, Nigeria.

SUBJECTS: Thirty eight sickle cell anaemia patients.

RESULTS

HbF levels estimated by the two methods showed good agreement as estimated by the Bland-Altman plot. HbF levels obtained by Betke's method correlated well with those obtained by the elution method (r = 0.59, p = 0.0015) and the mean values were similar (14.9% versus 13.5%, p=0.215). The values obtained by the analogue spectrophotometer showed poor agreement with those obtained by the digital instrument, with the mean value of the former being much lower than that of the latter.

CONCLUSION

Both Betke's method and the elution method give similar results in the estimation of HbF so that for practical purposes, the two methods are interchangeable. The type of spectrophotometer used may have a major influence on HbF values obtained. Therefore, such information should be stated in any study reporting HbF values to facilitate interpretation.