Background Anaemia in neonates may cause symptoms due to impaired tissue oxygenation. Blood lactate concentration [L] may be a better marker of the significance of symptoms in the presence of anaemia than haemoglobin concentration [Hb].

Subjects [L] (mMol/L) was reviewed in 3 groups of babies: non-anaemic controls (n=90. median gestation 29w); anaemic without symptoms(n=26, median gestation 26w) anaemic with symptoms (n=17. median gestation 28w).

Results There was a correlation between [L] and [Hb] (n=125, r=-0.37, p<0.001). [L] (mean = sd) was higher than controls(0.69±0.2) in symptomatic babies (0.92 ± 0.22) (p<0.001), but not in asymptomatic ones (0.75±0.27) (p=0.29). It fell after transfusion in the asymptomatic (0.57±0.23) (p=0.006) and symptomatic groups (0.64±0.15) (p=0.001). [L] was significantly higher in infants with symptomatic anaemia compared with those without symptoms (p<0.01), but[Hb] in these two groups was not different (p=0.17).

Conclusions The observation that elevated [L] was associated with symptoms may be related to inadequate tissue oxygenation. A low [Hb] may not always be associated with impaired tissue oxygenation.