Human neutrophil lipocalin: normal levels and use as a marker for invasive infection in the newborn.
OBJECTIVE
To evaluate human neutrophil lipocalin (HNL) as a marker of neonatal invasive infection and determine the normal serum levels of HNL in newborns.


METHODS
HNL is released from neutrophil granulocytes and is regarded as a specific marker of neutrophil activity. In 81 newborns < or = 28 d of age with signs of infection on a total of 87 occasions, HNL and C-reactive protein (CRP) were measured at inclusion and on the three following days. As controls, term healthy newborns were recruited at birth (cord blood, n = 45) and at ages 3-5 d (n = 46). Serum HNL was measured by a radioimmunoassay.


RESULTS
25/87 episodes were classified as infection and 62 as non-proven infection. HNLmax was significantly higher in the infected group (mean 587.6 microg/l) than in the non-proven infected group (mean 217.7 microg/, p < 0.001). HNL peaked at inclusion, 1 d earlier than CRP. In the healthy controls. HNL was the same at 3-5 d of age as at birth (mean 82.4-81.7 microg/l) and similar to normal adult levels.


CONCLUSIONS
The release of HNL is not increased in healthy newborns at birth, but neonatal neutrophils rapidly release HNL upon microbial stimulation in vivo. HNL might be useful as an early marker of neonatal infection.
Björkqvist
M
M
Department of Paediatrics, Orebro University Hospital, Orebro, Sweden. maria.bjorkqvist@orebroll.se
Källman
J
J
Fjaertoft
G
G
Xu
S
S
Venge
P
P
Schollin
J
J
D000209:Acute-Phase Proteins; D016470:Bacteremia / Q000175:diagnosis*; D015415:Biomarkers / Q000097:blood*; D001724:Birth Weight; D002097:C-Reactive Protein / Q000032:analysis; D002352:Carrier Proteins; D005260:Female; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D000071068:Lipocalin-2; D054834:Lipocalins; D008297:Male; D009504:Neutrophils / Q000378:metabolism*; D015513:Oncogene Proteins; D011518:Proto-Oncogene Proteins; D011863:Radioimmunoassay / Q000379:methods; D012680:Sensitivity and Specificity
D000209:Acute-Phase Proteins; D015415:Biomarkers; D002352:Carrier Proteins; C489506:LCN2 protein, human; D000071068:Lipocalin-2; D054834:Lipocalins; D015513:Oncogene Proteins; D011518:Proto-Oncogene Proteins; D002097:C-Reactive Protein