Stability of BUN and creatinine determinations on the Siemens Advia 1800 analyzer.
BACKGROUND
Serum creatinine values of patients tend to change as a result of the use of different blanks used for creatinine determinations on the Advia 1650. After upgrading the analyzer to the Advia 1800, creatinine values tended to be more reproducible. As part of a quality assurance investigation to test the reproducibilities of creatinine values, we determined serial creatinine values in the sera of 13 patients whose initial values were either in the reference range or elevated (range 0.58-7.8 mg/dl). These values were determined concurrently with serum blood urea nitrogen (BUN) determinations (range 6.0-84.4 mg/dl) as these two analytes are used together in evaluation of renal function.


METHODS
We determined BUN and creatinine values, using the glutamate dehydrogenase lined enzyme assay system and the Jaffe method, respectively.


RESULTS
We find that all values for creatinine on samples stored at 4 °C were reproducible as were the corresponding BUN values, which is revealed by low values for the coefficients of variation (CVs), that is, mean CV of 4.55% for creatinine and 2.52% for BUN. One sample with relatively high CV (10.6%) for creatinine was found to have an initial value of 1.1 mg/dl, in the reference range; but, on repeat determinations, the obtained levels were as high as 1.5 mg/dl, above the reference range. BUN values for this sample remained in the reference range, suggesting that no renal disease was present.


CONCLUSIONS
We conclude that creatinine and BUN determinations are stable, but occasional spurious creatinine values can occur on the Advia 1800 analyzer.
Department of Pathology and Laboratory Medicine, NY Harbor VA Medical Center 800 Poly Place, Brooklyn, New York; Department of Pathology, SUNY Downstate Medical Center, Brooklyn, New York.
Jia
J
Qin
Huiying
H
Wang
Anton
A
Rets
Saul
S
Harari
Herol
H
Alexis
Ikram
I
Eid
Matthew R
MR
Pincus
D001774:Blood Chemical Analysis / Q000295:instrumentation* / Q000379:methods*; D001806:Blood Urea Nitrogen; D003404:Creatinine / Q000097:blood* / Q000737:chemistry; D006801:Humans; D015203:Reproducibility of Results; D014508:Urea / Q000097:blood* / Q000737:chemistry
D014508:Urea; D003404:Creatinine
Advia 1800 analyzer; BUN; coefficient of variation; creatinine; stability