title: The diagnostic value of cerebrospinal fluid chemistry results in childhood tuberculous meningitis.
abstract: OBJECTIVE
  Cerebrospinal fluid (CSF) hypoglycorrhachia and elevated protein is well-described in bacterial meningitis, but evidence for its differential diagnostic value in tuberculous meningitis (TBM) is lacking. We aimed to assess the diagnostic utility of CSF glucose, CSF to serum glucose ratio and CSF protein in children with suspected TBM.
  
  
  METHODS
  We describe CSF glucose and protein values as well as CSF to serum glucose ratios in a prospective evaluation of TBM suspects seen at Tygerberg Children's Hospital, Cape Town, South Africa, from January 1985 to January 2014.
  
  
  RESULTS
  Of 615 TBM suspects, 88 (14%) had microbiologically confirmed TBM, 381 (62%) 'probable' TBM and 146 (24%) 'non-TBM'. Mean absolute CSF glucose concentration was significantly lower in the microbiologically confirmed (1.87 ± 1.15 mmol/L) and 'probable' TBM (1.82 ± 1.19 mmol/L) groups compared to non-TBM (3.66 ± 0.88 mmol/L). A CSF glucose concentration of <2.2 mmol/L diagnosed TBM with sensitivity 0.68 and specificity 0.96. Sensitivity using a CSF to serum glucose ratio of <0.5 was 0.90. Mean CSF protein was significantly elevated in the microbiologically confirmed TBM (1.91 ± 1.44 g/L) and 'probable' TBM (2.01 ± 1.49 g/L) groups compared to the non-TBM (0.31 ± 0.31 g/L). A CSF protein >1 g/L diagnosed TBM with sensitivity 0.78 and specificity 0.94.
  
  
  CONCLUSIONS
  Absolute CSF glucose values of <2.2 mmol/L and protein values of >1 g/L differentiated between TBM and non-bacterial meningitis with good specificity, although sensitivity was poor. A CSF to serum glucose ratio is more informative than the absolute value.
authors.affiliation: Department of Paediatrics and Child Health, Faculty of Medicine and Health Sciences, Stellenbosch University, PO Box 19063, Tygerberg, 7505, Cape Town, South Africa, regan@sun.ac.za.
authors.forename: R S
authors.initials: RS
authors.lastname: Solomons
authors.forename: D H
authors.initials: DH
authors.lastname: Visser
authors.forename: P R
authors.initials: PR
authors.lastname: Donald
authors.forename: B J
authors.initials: BJ
authors.lastname: Marais
authors.forename: J F
authors.initials: JF
authors.lastname: Schoeman
authors.forename: A M
authors.initials: AM
authors.lastname: van Furth
mesh_terms: D002556:Cerebrospinal Fluid Proteins / Q000378:metabolism*; D002648:Child; D002675:Child, Preschool; D003937:Diagnosis, Differential; D005260:Female; D005947:Glucose / Q000134:cerebrospinal fluid*; D015658:HIV Infections / Q000150:complications; D006801:Humans; D007223:Infant; D008137:Longitudinal Studies; D008297:Male; D059906:Neuroimaging; D012372:ROC Curve; D012189:Retrospective Studies; D012720:Severity of Illness Index; D014390:Tuberculosis, Meningeal / Q000134:cerebrospinal fluid* / Q000175:diagnosis* / Q000382:microbiology / Q000821:virology
chemical_list: D002556:Cerebrospinal Fluid Proteins; D005947:Glucose