Acidification should replace NaF alone as the recommended method for obtaining an accurate glucose concentration. Diagnostic cut points based on blood samples collected into tubes containing NaF as the only inhibitor of glycolysis are likely to be too low.

Objective: The potential eects of ethnicity, gender, and adiposity on the serum lipid pro®le in persons with spinal cord injury (SCI) were determined. Subjects: Subjects with SCI were recruited during their annual physical examination from Rancho Los Amigos Medical Center, Downey, California. Sedentary able-bodied controls were Bridge and Tunnel Ocers of the Triboro Bridge and Tunnel Authority of the New York City metropolitan area. Methods: Serum lipid pro®les were investigated in 320 subjects with SCI and compared to those obtained from 303 relatively sedentary able-bodied controls. Serum lipid studies were obtained in the fasting state. Data were collected between 1993 and 1996. All lipid determinations were performed by the same commercial laboratory. Main outcome measures: The dependent variables were the values from the lipid pro®le analysis. The independent variables consisted of study group, gender, ethnic group, age, duration of injury, and anthropometric measurements. Results: The serum high-density lipoprotein cholesterol (HDL-c) level was reduced in the SCI compared with the control group (mean+SEM) (42+0.79 vs 47+0.67 mg/dl, P50.0005). The serum HDL-c level was signi®cantly lower in males with SCI than males in the control group (39+0.83 vs 45+0.70 mg/dl, P50.0001), but not for females (51+1.54 vs 54+1.52 mg/ dl, n.s.). Within the subgroups for whites and Latinos, HDL-c values were also lower in subjects with SCI than in controls (whites: 41+1.02 vs 46+0.86 mg/dl, P50.0001; Latinos: 37+1.53 vs 42+1.59 mg/dl, P50.05), but not for African Americans (49+1.56 vs 51+1.27 mg/dl, n.s.). African Americans had higher HDL-c values than whites or Latinos (SCI: 49+1.56 vs 41+1.02 or 37+1.53 mg/dl, P50.0001; controls: 51+1.27 vs 46+0.86 mg/ dl, P50.01 or 42+1.59 mg/dl, P50.0005). In persons with SCI, the serum HDL-c values were inversely related to body mass index and estimated per cent body fat (r=0.27, P50.0001). Conclusion: In white and Latino males, but not in females or African Americans, immobilization from SCI appears to be associated with lower HDL-c values than in controls.

Entrenched in current laboratory protocols for the measurement of plasma glucose is the false belief that sodium fluoride (NaF) is an effective inhibitor of glycolysis. The failure of NaF to properly control glycolysis decreases plasma glucose concentrations. The amount of the decrease can be clinically significant. The most recent (2011) laboratory guidelines for diagnosis and management of diabetes mellitus, approved by the American Diabetes Association, no longer recommend the use of NaF alone to control glycolysis. If plasma cannot be iced and separated from cells within 30 min of collection, the new guidelines recommend the use of a tube that contains a low pH buffer such as citrate. Proper control of glycolysis will affect current glucose cut-off points, but the exact effect is yet to be defined.

We sought to determine if serum total iron-binding capacity (TIBC) is equivalent to serum transferrin (TRF) so that a low-cost colorimetric chemical assay for unsaturated iron-binding capacity (UIBC) could be substituted for a high-cost immunologic assay for TRF. Our study design included independent and blinded measurements of UIBC, serum iron, and TRF concentrations in human serum samples. Data from five independent correlation studies carried out at three different Quest Diagnostics laboratories were combined into one data set containing 570 paired results for TIBC and TRF. r2 was 0.941 when three outliers were eliminated from the 570-sample data set. Scatter about the regression line was fully accounted for by the CVs for the TIBC and TRF assays. When each test is measured precisely and without bias, the ratio of TIBC (μmol/L) to TRF (g/L) in SI units is close to the theoretically expected value of 25.0.

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