title: Are tubes containing sodium fluoride still needed for the measurement of blood glucose in hospital laboratory practice?
abstract: OBJECTIVE
  To compare glucose values obtained using sodium flouride (NaF) tubes and serum separation tubes (SST) in a tertiary care hospital laboratory setting.
  
  
  METHODS
  This study was conducted at the Clinical Biochemistry Laboratory, Royal Hospital, Oman. During the study period (1 September-30 November 2013), 50 pairs (one NaF tube and one SST) of patient's blood specimens were randomly collected. Following separation of plasma (NaF tubes) and serum (SST), glucose concentrations were measured by hexokinase assay using the Architect c8000. Fifteen pairs of these tubes were kept in the refrigerator at 4°C and plasma/serum glucose concentrations were measured daily up to seven days after collection.
  
  
  RESULTS
  Comparing plasma (NaF) and serum (SST) results of glucose values (n=50) showed an average difference of 0.00mmol/L (range -0.60 to +0.60mmol/L). Bland Altman analysis gave a non-significant constant bias of 0.10 ±0.195mmol/L (bias ±SD). Pearson correlation between plasma (NaF) and serum (SST) glucose concentrations revealed a significant correlation approaching unity with r(2)= 0.9991. No significant differences in glucose values were noted for both plasma and serum in 15 pairs of NaF and SST tubes when analyzed seven days following refrigeration. Hemolysis was observed in five (10%) NaF tubes compared with two (4%) SST.
  
  
  CONCLUSIONS
  There is no difference in glucose values collected from plasma NaF tubes or serum SST, and so SST can be used in hospital laboratory settings as there are practical advantages, including cost-effectiveness and reduction in blood volume drawn when utilizing these tubes for glucose and other tests from a single blood collection tube.
authors.affiliation: Department of Chemical Pathology, Royal Hospital, Muscat, Oman.
authors.forename: Amira
authors.initials: A
authors.lastname: Al-Kharusi
authors.affiliation: Department of Chemical Pathology, Royal Hospital, Muscat, Oman.
authors.forename: Nuha
authors.initials: N
authors.lastname: Al-Lawati
authors.affiliation: Department of Chemical Pathology, Royal Hospital, Muscat, Oman.
authors.forename: Manal
authors.initials: M
authors.lastname: Al-Kindi
authors.affiliation: Department of Chemical Pathology, Royal Hospital, Muscat, Oman.
authors.forename: Waad-Allah
authors.initials: WA
authors.lastname: Mula-Abed
keywords: Blood glucose; Diabetes mellitus; Serum separator tubes (SST); Sodium fluoride