An assessment of lyophilized serum with stated values

Abstract

In its most recent survey of common serum components, the AACB (S.A. Branch) used 6 frozen reconstituted lyophilized sera. The object was to assess the reliability of stated values. The results indicated that assumption of accuracy and stability of stated values in these sera was justified for sodium, potassium, chloride, bicarbonate, urea, glucose, uric acid, creatinine, calcium, magnesium and phosphorus. Discrepancies between stated and observed values were traced to factors other than serum quality. Results for ALP, LD, cholesterol and triglycerides confirmed previous conclusions that these methods require standardization before interlaboratory comparisons become useful. Significant discrepancies found with total protein and albumin resulted from the use of single-point standardization in non-linear methods. Serious variable losses of bilirubin were found in Technicon sera but not in General Diagnostics sera. The use of frozen reconstituted lyophilized serum in bilirubin assays should be avoided until long term stability is confirmed.