title: Reliability of acute illness dihydrorhodamine-123 testing for chronic granulomatous disease.
abstract: BACKGROUND
  Dihydrorhodamine (DHR) flow cytometric analysis is used to evaluate granulocyte oxidative bursts and is the test of choice for the diagnosis of chronic granulomatous disease (CGD). We present the clinical and DHR test profiles of five subjects assessed during and after acute illness.
  
  
  METHODS
  This was a retrospective report of the findings of five out of a total of one hundred and seventeen patients, whose blood was sent to the laboratory for dihydrorhodamine-123 flow cytometry testing between January 2005 and December 2010. Using whole blood technique and stimulation using phorbol myristate acetate, the results of DHR were expressed as stimulation index and coefficient of variation of histograms of stimulated cells and compared with healthy controls. DHR tests were repeated when the patients had recovered and were clinically well.
  
  
  RESULTS
  These five patients showed abnormal DHR test results during their acute illness, with a stimulation index (SI) lower (p = 0.009) and coefficient of variation (CV) higher (p = 0.009) than controls. The DHR profiles repeated when patients had recovered showed normalization of tests with no significant difference for SI (p = 0.602) and CV (p = 0.917) compared to controls. Wilcoxon Signed Rank tests showed a significant improvement in SI (p = 0.043) and CV (p = 0.043) upon recovery. On follow up, all five patients were well, with no further severe or atypical infections.
  
  
  CONCLUSIONS
  DHR may be transiently abnormal during acute illness, and may therefore not be reliable when assessed during an acute illness. If these subjects had CGD, it would be of a hypomorphic variant that has not previously been described.
authors.affiliation: University Children's Medical Institute, National University Health Systems, Singapore.
authors.forename: E Y
authors.initials: EY
authors.lastname: Ang
authors.forename: Y N
authors.initials: YN
authors.lastname: Ang
authors.forename: J Y
authors.initials: JY
authors.lastname: Soh
authors.forename: W K
authors.initials: WK
authors.lastname: Liew
authors.forename: K W
authors.initials: KW
authors.lastname: Chan
authors.forename: K C
authors.initials: KC
authors.lastname: Thoon
authors.forename: C Y
authors.initials: CY
authors.lastname: Chong
authors.forename: Y L
authors.initials: YL
authors.lastname: Lau
authors.forename: B W
authors.initials: BW
authors.lastname: Lee
mesh_terms: D005434:Flow Cytometry; D006105:Granulomatous Disease, Chronic / Q000175:diagnosis*; D006801:Humans; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012235:Rhodamines
chemical_list: D012235:Rhodamines; C058319:dihydrorhodamine 123