title: The effect of extremely high glucose concentrations on 21 routine chemistry and thyroid Abbott assays: interference study.
abstract: BACKGROUND
  Extremely high glucose concentrations have been shown to interfere with creatinine assays especially with Jaffe method in peritoneal dialysate. Because diabetes is the fastest growing chronic disease in the world, laboratories study with varying glucose concentrations. We investigated whether different levels of glucose spiked in serum interfere with 21 routine chemistry and thyroid assays at glucose concentrations between 17-51 mmol/L.
  
  
  METHODS
  Baseline (group I) serum pool with glucose concentration of 5.55 (5.44-5.61) mmol/L was prepared from patient sera. Spiking with 20% dextrose solution, sample groups were obtained with glucose concentrations: 17.09, 34.52, and 50.95 mmol/L (group II, III, IV, respectively). Total of 21 biochemistry analytes and thyroid tests were studied on Abbott c8000 and i2000sr with commercial reagents. Bias from baseline value was checked statistically and clinically.
  
  
  RESULTS
  Creatinine increased significantly by 8.74%, 31.66%, 55.31% at groups II, III, IV, respectively with P values of < 0.001. At the median glucose concentration of 50.95 mmol/L, calcium, albumin, chloride and FT4 biased significantly clinically (-0.85%, 1.63%, 0.65%, 7.4% with P values 0.138, 0.214, 0.004, < 0.001, respectively). Remaining assays were free of interference.
  
  
  CONCLUSIONS
  Among the numerous biochemical parameters studied, only a few parameters are affected by dramatically increased glucose concentration. The creatinine measurements obtained in human sera with the Jaffe alkaline method at high glucose concentrations should be interpreted with caution. Other tests that were affected with extremely high glucose concentrations were calcium, albumin, chloride and FT4, hence results should be taken into consideration in patients with poor diabetic control.
authors.affiliation: Katip Celebi University, Ataturk Training and Research Hospital, Department of Clinical Biochemistry, Izmir, Turkey.
authors.forename: Serap
authors.initials: S
authors.lastname: Çuhadar
authors.affiliation: Katip Celebi University, Ataturk Training and Research Hospital, Department of Clinical Biochemistry, Izmir, Turkey.
authors.forename: Mehmet
authors.initials: M
authors.lastname: Köseoğlu
authors.affiliation: Abant İzzet Baysal University, Department of Clinical Biochemistry, Bolu, Turkey.
authors.forename: Yasemin
authors.initials: Y
authors.lastname: Çinpolat
authors.affiliation: Abant İzzet Baysal University, Department of Clinical Biochemistry, Bolu, Turkey.
authors.forename: Güler
authors.initials: G
authors.lastname: Buğdaycı
authors.affiliation: Giresun University, Department of Clinical Biochemistry, Giresun, Turkey.
authors.forename: Murat
authors.initials: M
authors.lastname: Usta
authors.affiliation: Giresun University, Department of Clinical Biochemistry, Giresun, Turkey.
authors.forename: Tuna
authors.initials: T
authors.lastname: Semerci
mesh_terms: D001786:Blood Glucose / Q000378:metabolism*; D002118:Calcium / Q000097:blood; D002712:Chlorides / Q000097:blood; D019963:Clinical Chemistry Tests / Q000379:methods / Q000592:standards*; D003404:Creatinine / Q000097:blood; D003920:Diabetes Mellitus / Q000097:blood / Q000628:therapy; D006801:Humans; D010530:Peritoneal Dialysis; D015203:Reproducibility of Results; D012709:Serum Albumin / Q000032:analysis; D013960:Thyroid Function Tests / Q000379:methods / Q000592:standards*; D013961:Thyroid Gland / Q000378:metabolism*; D013974:Thyroxine / Q000097:blood
chemical_list: D001786:Blood Glucose; D002712:Chlorides; D012709:Serum Albumin; D003404:Creatinine; D013974:Thyroxine; D002118:Calcium
keywords: Jaffe kinetic assay; assay interference; creatinine; glucose interference; preanalytical phase; thyroid function tests