Analytical interferences resulting from intravenous lipid emulsion.
BACKGROUND
Lipid resuscitation therapy using intravenous lipid emulsion (IVLE) for drug overdoses has gained widespread use. However, there is little information regarding its adverse effects.


OBJECTIVE
We performed lipemic interference studies on typical automated platforms to investigate the potential of lipid resuscitation therapy to interfere with the reliability and turnaround time of analytes that would be of interest in acute intoxications. We also tested methods to minimize interferences.


METHODS
Serum pools were supplemented with increasing concentrations of Intralipid-20%(®) (0-30%). Analyses were performed on Beckman-Coulter DXC800 and DXI and Roche Modular-P. Analytes demonstrating significant interference were re-measured after centrifugation (14 000 × g for 10 minutes).


RESULTS
Triglyceride and glycerol-blanked triglyceride concentrations were similar in IVLE-free samples. However, with addition of IVLE, concentrations were markedly different (139 vs. 76 mmol/L). There was no appreciable interference on the troponin-I, sodium, potassium, chloride, calcium, bicarbonate or urea assays. Albumin and magnesium assays demonstrated significant interference. Amylase, lipase, phosphate, creatinine, total protein, ALT, CK and bilirubin became unmeasurable in IVLE-supplemented samples. Whereas glucose measurement by potentiometry was free of interference, colorimetric methodology was error prone. Centrifugation removed > 90% of glycerol-blanked triglyceride (max = 5.8 mmol/L), dramatically reducing lipid interferences.


CONCLUSIONS
IVLE results in appreciable analytical interferences at concentrations demonstrated in lipid resuscitation therapy. Of particular concern is the marked interference on glucose and magnesium, which may result in unsuccessful and potentially harmful interventions. Major implications for patient care include reporting of incorrect results and delays in the reporting of time-sensitive results. Whenever possible, blood samples should be collected prior to initiating lipid therapy. Interferences can be minimized by brief centrifugation at relatively low speeds on equipment readily available in most core labs.
Division of Medical Biochemistry, Department of Medicine, McGill University Health Centre, Montreal, QC, Canada. ami.grunbaum@mail.mcgill.ca
Ami M
AM
Grunbaum
Brian M
BM
Gilfix
Sophie
S
Gosselin
David W
DW
Blank
D001774:Blood Chemical Analysis; D001786:Blood Glucose / Q000032:analysis; D004573:Electrolytes / Q000097:blood; D004655:Emulsions; D005217:Fat Emulsions, Intravenous / Q000032:analysis*; D006801:Humans; D008027:Light; D010743:Phospholipids / Q000097:blood*; D012542:Scattering, Radiation; D013024:Soybean Oil / Q000097:blood*; D014280:Triglycerides / Q000097:blood; D019210:Troponin I / Q000097:blood
D001786:Blood Glucose; D004573:Electrolytes; D004655:Emulsions; D005217:Fat Emulsions, Intravenous; D010743:Phospholipids; D014280:Triglycerides; D019210:Troponin I; C545823:soybean oil, phospholipid emulsion; D013024:Soybean Oil