The reliability of serum theophylline determinations from clinical laboratories.
Three aliquots of pooled serum containing theophylline and disguised as patient specimens were sent, one at a time, on different days, to 29 community hospital and referral laboratories serving Iowa. The mean +/- SEM concentration of 65 replications for the same serum pool was 15.7 +/- 0.1 microgram/ml. Twenty-eight per cent of the 85 measurements reported by the clinical laboratories were outside the acceptable range of 13.2 to 18.1 microgram/ml established by the 95% confidence limits of the assayed pool. Reliability of the results was not related to the type of facility, method of measurement, or fee charged. Therefore, variation in clinical laboratory performance was a result of technician error in handling or analyzing the specimens. We conclude that measurements of serum theophylline can only be relied on to adjust dosage when the accuracy of the laboratory has been established with blinded samples.
D004311:Double-Blind Method; D005069:Evaluation Studies as Topic; D006801:Humans; D007484:Iowa; D007753:Laboratories / Q000592:standards*; D013806:Theophylline / Q000097:blood* / Q000592:standards
D013806:Theophylline