Laboratory samples deemed 'unsuitable for analysis' can be diagnostically useful

Evaluating Interference of Lipemia on Routine Clinical Biochemical Tests

Objective Lipemia is an important cause of preanalytical errors in laboratory results. They affect the specimen integrity and trustworthiness of laboratory results. The present study was to assess the impact of lipemia on routine clinical chemistry analytes.

Methods Anonymous leftover serum samples with normal levels of routine biochemical parameters were pooled. Twenty such pooled serum samples were used for the study. The samples were spiked with commercially available intralipid solution (20%) to produce lipemic concentrations of 0, 400 (mild, 20 μL), 1,000 (moderate, 50 μL), and 2,000 mg/dL (severe, 100 μL). Glucose, renal function test, electrolytes, and liver function test were estimated in all the samples. Baseline data without the effect of interference was considered as true value and percentage bias for the spiked samples was calculated. Interference was considered significant if the interference bias percentage exceeded 10%.

Result Parameters like glucose, urea, creatinine, direct bilirubin, sodium, potassium, and chloride showed negative interference at mild and moderate lipemic concentration and positive interference at severe lipemic concentration. Parameters like aspartate transaminase (AST) and alanine transaminase (ALT) showed negative interference at mild and positive interference at moderate and severe lipemic concentration. Whereas uric acid, total protein, albumin, total bilirubin, alkaline phosphatase, gamma-glutamyl transferase, calcium, magnesium, and phosphorous showed positive interference at all concentrations. Significant interference (> 10%) was shown for magnesium (mild lipemia), albumin, direct bilirubin, ALT, and AST at moderate lipemic concentration. All parameters showed significant interference at severe lipemic concentration.

Conclusion All the study parameters are affected by lipemic interference at varying levels. Laboratory-specific data regarding lipemic interference at various concentrations on the clinical biochemistry parameters is needed.

Effect of interference from hemolysis, icterus and lipemia on routine pediatric clinical chemistry assays

BACKGROUND

Clinical laboratory assays can be affected by interferents like hemoglobin (Hb), lipids and bilirubin. We evaluated the effect of these interferences on pediatric samples for different chemistry assays. Further we established cut-off indices above which these interferences confound sample results.

METHODS

Three separate serum pools were spiked with increasing concentrations of hemolysate or intralipid or bilirubin and different analytes were analyzed. The Hemolysis-(H), Lipemia-(T) and Icterus-(I) indices were measured on Vitros 5600. Analytes affected by lipemia were treated with LipoClear ® and re-analyzed. All the measured analytes were compromised by gross hemolysis (H-Index >1000).

RESULTS

Except lipase and magnesium (Mg(++)), all other analytes were affected by moderate (H-Index >250) and significant hemolysis (H-Index >500). Low estradiol levels showed a significant effect at severe icterus (I-Index >20.0). C3, C4, Ceruloplasmin, Haptoglobin, Immunoglobulins (Ig) and Vitamin D were significantly affected by moderate (T-Index >100) and severe (T-Index >500) lipemia. LipoClear ® treatment significantly attenuated the lipemic interference on the above analytes except for C3, C4, and IgG.

CONCLUSIONS

Accurate reporting of pediatric samples for the analytes affected by common interferences will lead to better clinical interpretation.