Normal range for glucose in urine: age-related changes.

The Du Pont aca “NBIL” test (Du Pont Instruments, Wilmington, DE 19898) also measures bilirubin spectrophotometrically. Figure 2 shows an approximate linear relationship between “apparent” biliburin concentration, as measured with the Bilirubin Stat-Analyzer and the aca NBIL test, vs Liposyn concentration in a neonatal serum sample. This sample without added Liposyn gave identical total bilirubin values with both instruments (111 mg/L). To correct for this interference, add 30 mg of potassium persulfate to the saline-diluted sample after obtaining the total bilirubin reading on the Bilirubin Stat-Analyzer. Mix the solution to dissolve the persulfate and let it stand 5 mm before taking a second total bilirubin reading. The bilirubin is oxidzed and no longer absorbs at 454 nm; therefore, the difference between the first and second total bilirubin readings represents the corrected bilirubin concentration. The Biirubin Stat-Analyzer readings after persulfate treatment of each of 14 sera from neonates is shown in Table 1 along with the corrected bilirubin concentration. Linear regression of the corrected bilirubin values (y) on the original values (x) before addition of Liposyn gave the following equation: y = 1.037x 0.97 mg/L (r = 0.989). The oxidation of the bilirubin appears to be complete at 5 mm, no further change in total bilirubin concentration being noted 10 mm after persulfate addition. This blanking procedure provides a viable alternative to diazotization procedures for measuring bilirubin in lipemic specimens. It is important that laboratory personnel carefully examine specimens from newborns for turbidity when performing bilirubin assays. References