Blood Sampling for Serum Triglycerides During IV Lipid Infusion
When drawing blood for serum triglyceride measurement in a patient receiving intravenous lipid infusion, temporarily stop the lipid infusion for at least 4 hours before sampling, or draw from a peripheral site that is not the same line or contralateral to the infusion site to avoid direct contamination. If neither option is feasible, ensure the blood sample is drawn from a location with adequate dead space clearance and document that the patient is receiving IV lipids so the laboratory can interpret results appropriately 1, 2.
Primary Sampling Strategy
Stop the lipid infusion 4 hours before drawing the sample, as hypertriglyceridemia from IV lipid administration peaks approximately 4 hours after infusion and this timing allows for more accurate baseline assessment 2.
Draw blood from a peripheral venipuncture site that is completely separate from the IV lipid infusion line to eliminate any risk of direct contamination with the lipid emulsion 1.
If using a central line with multiple ports, draw from the port most distant from the lipid infusion port and ensure adequate flushing of dead space volume (typically 5 mL minimum) before obtaining the sample 1.
Critical Technique When Sampling from Lines
Flush the catheter and discard the first 5 mL of blood before collecting the sample to clear any residual lipid emulsion from the catheter dead space 1.
Use a straight needle for peripheral venipuncture rather than a butterfly needle when possible, as butterfly needles have longer connecting tubes that increase dead space and potential for sample contamination 1.
Avoid drawing blood from the same extremity where lipids are infusing, even from a different vein, as there may be local elevation of triglyceride concentrations 1.
Laboratory Considerations
Inform the laboratory that the patient is receiving IV lipid emulsion so they can anticipate potential lipemia interference with optical measurement systems used in automated analyzers 3.
Request manual mechanical endpoint detection methods or high-speed centrifugation if severe lipemia is present, as these techniques can provide reliable results even with elevated lipid concentrations 3.
Recognize that automated coagulation analyzers using optical measurements may fail completely with high lipid concentrations, requiring alternative analytical approaches 3.
Timing Considerations for Monitoring
Check triglycerides during or within 4 hours of lipid infusion when assessing for acute complications like fat overload syndrome, as this is when hypertriglyceridemia peaks 2.
For routine monitoring during parenteral nutrition, check triglycerides 1-2 days after TPN initiation or adjustment, then weekly to monthly depending on patient stability 4.
In high-risk patients (sepsis, catabolism, extremely low birth weight infants), monitor triglycerides more frequently as these conditions impair lipid clearance 1, 4.
Common Pitfall to Avoid
Never draw blood for triglyceride measurement directly from the IV line infusing lipids without adequate dead space clearance, as this will result in falsely elevated values that do not reflect the patient's true metabolic state 1. The sample contamination can lead to inappropriate clinical decisions, such as unnecessarily stopping lipid administration and risking essential fatty acid deficiency 2, 4.
When Results Are Unexpectedly High
Verify the blood sampling technique and source to ensure no possibility of sample contamination with the lipid infusion 1.
Draw a confirmatory sample from the most appropriate alternative site (contralateral peripheral vein) if contamination cannot be ruled out 1.
Consider that true hypertriglyceridemia may be present if proper sampling technique was used, requiring dosage adjustment rather than complete cessation of lipids 1, 2, 4.