Bahr Timothy M, Albertine Kurt H, Christensen Robert D, Dahl Mar Janna, Rebentisch Andrew, Dawson Elaine, Major Emily, Foreman Hannah, Headden David, Vordos Zoë, Nabi Akbarali, Pettet Luke, Badrov Peter, Addison Connor, Christensen Daniel R
Division of Neonatology, Department of Pediatrics, University of Utah Health, Salt Lake City, Utah, UT 84132, USA.
Women and Newborn's Research, Intermountain Healthcare, Salt Lake City, Utah, UT 84132, USA.
Curr Pediatr Rev. 2023;19(4):425-428. doi: 10.2174/1573396319666221219153902.
Nucleated red blood cells (NRBC) are very uncommon in the blood of children and adults, but small numbers are not rare in neonates on the day of birth. Elevated NRBC counts in neonates can be seen following erythropoietin dosing. Limited studies in human neonates suggest the time-interval between erythropoietin dosing and the first appearance of NRBC in the blood (the "NRBC emergence-time") is in excess of 24 hours.
We made serial blood counts (Sysmex veterinary analyzer) on ten newborn lambs; five were dosed with darbepoetin (10 μg/kg), and five were dosed with a vehicle-control to assess the NRBC emergence time under relatively controlled laboratory conditions.
The first appearance of NRBC was at 24 h (2757 ± 3210 NRBC/μL vs. 0/μL in controls). Peak was 48-72 h (16,758 ± 8434/μL vs. 0/μL in controls), followed by fewer at 96 hours (7823 ± 7114/μL vs. 0/μL in controls). Similarly, reticulocytes peaked at 48-72 h (113,094 ± 3210/μL vs. 10,790 ± 5449/μL in controls), with no changes in platelets or leukocytes.
The NRBC emergence time in newborn lambs is similar to reports from newborn humans. By extrapolation, if a neonate has a high NRBC at birth, the erythropoietic stimulus likely occurred within the interval 24 to perhaps 96+ hours prior to birth.
有核红细胞（NRBC）在儿童和成人血液中非常罕见，但在出生当天的新生儿中少量存在并不罕见。新生儿促红细胞生成素给药后可见NRBC计数升高。对人类新生儿的有限研究表明，促红细胞生成素给药与血液中首次出现NRBC（“NRBC出现时间”）之间的时间间隔超过24小时。
我们对10只新生羔羊进行了系列血细胞计数（Sysmex兽医分析仪）；5只给予达贝泊汀（10μg/kg），5只给予溶媒对照，以在相对受控的实验室条件下评估NRBC出现时间。
NRBC首次出现于24小时（2757±3210个NRBC/μL，而对照组为0/μL）。峰值出现在48 - 72小时（16,758±8434/μL，而对照组为0/μL），随后在96小时时数量减少（7823±7114/μL，而对照组为0/μL）。同样，网织红细胞在48 - 72小时达到峰值（113,094±3210/μL，而对照组为10,790±5449/μL），血小板和白细胞无变化。
新生羔羊的NRBC出现时间与新生儿的报道相似。由此推断，如果新生儿出生时NRBC数量高，促红细胞生成刺激可能发生在出生前24至可能96 +小时的时间段内。
