Leukemoid reaction in a non-down pretrerm infant. What causes it?

[abeluchin]

A 29 2/7 weeks male infant was born two days ago from a 25 y/o G1P0 healthy pregnant mom. MOC showed up in preterm labor, with PPROM, and infant was born by CS due to NRFHT. Apgars 2 and 8. Infant intubated at delivery, given curosurf and weaned from the vent over 6hours. Tolerated HFNC at 5 lpm, on 20's FiO2. Amp and Gent started for suspected sepsis. Maternal serology was negative, (HIV, RPR, GBS). No maternal chorio. A CBC at 24 HOL showed WBC in the 65k, with 19% Bands, 11% myelos, 7% meta. Baby otherwise clinically stable. No phenotypic features of down syndrome.
1- What causes this phenomenum?
2- How log does it ussually last?
30 any reference article of idipathtic LR in this population?
Thanks for your kind help

[JACK]

First question: What is the nucleated RBC count ? Many times a high nRBC count gives a falsely elevated coulter WBC count.

[abeluchin]

NRBC count was low < 10%

[kpsanghvi]

I have seen leukemoid reactions 4 times in the past 20 years in non-Trisomy 21 babies. TLC > 50k. DLC Polys > 75-80. On three occasions it was gram negative septicemia. In one infant I remember, the counts were 20k in the morning and rose to 45k after 6 hours. In another active baby the count went on increasing over a couple of days (despite being on antibiotics) and eventually the blood culture grew Gm negative bacilli (Can't remember the bug). Only one child had unexplained high counts which settled down over a period of one month

[amitkala]

antenatal steroids adminstration can cause leukemoid reaction in babies.
Cohen A, Barak M, Herschkowitz S, Zecca S. Leukemoid
reaction induced by prenatal administration of
betamethasone. Acta Paediatr Jpn 1993; 35: 534-536.

[Omer]

Leukemoid reaction in preterm babies a nice paper.
http://pediatrics.aappublications.org/cgi/content/full/peds.2004-1379v1
Omer Hamud
Toronto