Detection and quantitation of normal and variant haemoglobins: an analytical review.

As well as six 'normal' haemoglobins that occur at various stages of development, more than 800 abnormal or variant haemoglobins have been described. Many of these variant haemoglobins have no significant clinical consequences apart from causing confusion to clinicians and in laboratories; however, some of the variant haemoglobins result in major morbidity or mortality. The laboratory challenge is to detect these clinically significant haemoglobins and to identify them with sufficient accuracy for clinical purposes, as well as to quantitate both these and the 'normal' haemoglobins. The techniques used to detect and quantitate these haemoglobins in routine service laboratories are discussed in detail. Methods used by referral laboratories, such as mass spectrometry and DNA analysis, are briefly discussed. Haemoglobin analysis is most often undertaken as part of neonatal, antenatal or pre-anaesthetic screening; these programmes are reviewed, together with possible changes to neonatal screening and antenatal screening that may occur as part of the NHS National Plan.