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Effect of delay in analysis on neonatal cerebrospinal fluid parameters
  1. N T Rajesh1,
  2. Sourabh Dutta1,
  3. Rajendra Prasad2,
  4. Anil Narang1
  1. 1
    Department of Pediatrics, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India
  2. 2
    Department of Biochemistry, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India
  1. Correspondence to Dr S Dutta, Department of Pediatrics, PGIMER, Chandigarh 160012, India; sourabhdutta{at}yahoo.co.in

Abstract

Objectives: The effect of delayed analysis on cerebrospinal fluid (CSF) white blood cell (WBC) count and glucose has never been studied in neonates.

Design: Prospective cohort study.

Setting: Level III newborn unit.

Patients: Neonates undergoing lumbar puncture were enrolled after consent. CSF was analysed at baseline (30 minutes) for protein, WBC and glucose; and from the same sample for WBC and glucose after a lag of 2 h and 4 h after lumbar puncture. Those with traumatic/inadequate CSF were excluded. Subjects were classified in three groups (n  =  20 each) based on baseline WBC count: no WBC, 1–30 WBC and >30 WBC/μl. Analysis was by repeated-measures ANOVA.

Results: There was a significant decline in mean (SD) CSF glucose from baseline to 2 h and 4 h (41.0 (19) to 38.3 (19) and 36.2 (20) mg/dl, respectively) and WBC count (36 (45) to 28.6 (38) and 23.8 (34) cells/μl, respectively; both p<0.001). CSF glucose and WBC declined in all three groups (p<0.001). High baseline CSF WBC (p<0.001) and protein (p<0.001) was associated with a more rapid decline in the levels of CSF WBC, but not glucose. True CSF parameters could be predicted from 4-h parameters: “baseline glucose 5.4 + 0.98 (4-h glucose)” (adjusted R2 97.2%, p<0.001) and “baseline WBC 1.3 (4-h WBC) +0.05 (protein)” (adjusted R2 98.8%, p<0.001). In group 3, a diagnosis of meningitis (based on pleocytosis) would be missed in 52.6% and 78.9% subjects at 2 h and 4 h, respectively.

Conclusions: CSF WBC count and glucose decrease significantly with time. Reliance on WBC counts of delayed samples can result in underdiagnosis.

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Footnotes

  • Contributors: NTR collected the data and wrote the first draft, SD conceived the idea, planned the study, analysed the data and wrote the manuscript, RP performed biochemical analysis and AN supervised the study design and edited the manuscript.

  • Competing interests None.

  • Provenance and Peer review Not commissioned; externally peer reviewed.

  • Ethics approval The study protocol received ethics approval from the Institute Ethics Committee of the Postgraduate Institute of Medical Education and Research.

  • Patient consent Obtained.

  • Contributors: NTR collected the data and wrote the first draft, SD conceived the idea, planned the study, analysed the data and wrote the manuscript, RP performed biochemical analysis and AN supervised the study design and edited the manuscript.

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