Drip line contamination – Ringers Lactate

HOSP # WARD False Bay Hospital Casualties
CONSULTANT   DOB/AGE 33y Female

Abnormal Result

Urea 0.8 mmol/L; Creatinine 10 umol/L; Sodium 154 mmol/L; Potassium 5.4 mmol/L

Presenting Complaint

Above results do not make sense for a 33 year old female, except if muscle weight is extremely low.

History

Examination

N/A

Laboratory Investigations

Inspection of the sample:

Drip line contamination
On inspection of the sample it is clear that there is dilution with a clear fluid and the hematocrit is affected severely (also visible on results below).

Other Investigations

Lactate on analyser as done on serum sample: >22 mmol/L, dilution made: 1 in 10 revealed a lactate of 26.8 mmol/L in the sample. This could explain that Ringers Lactate was the contaminant in the sample, but can only be hypothesized with the available evidence.

Hematology results:

From the previous (and current) Hematology results available, it is clear that, since all values are lower than the previous day, drip line contamination is the likely cause of the low Chemistry and Hematology results.

Final Diagnosis

Take Home Messages

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Lactate cannot be measured in SST (serum separator tubes) without taking into account the fact that the red cells will continue to metabolize the glucose in the sample to lactate via anaerobic metabolism through glycolysis.

Lactate concentration increases linearly over time, in whole blood. Factors affecting the rate of production are, among others:

  • Temperature
  • Glucose concentration
  • Additives in the blood tubes such as NaF

NaF inhibits enolase, an enzyme acting late in the glycolytic pathway, and has no effect on enzymes that act early in the glycolytic pathway. … Glycolysis is instantly inhibited in erythrocytes, leukocytes and platelets when the blood pH is maintained between 5.3 and 5.9 with a citrate buffer.

Sage Journals: Ann Clin Biochem 2013;50: 3–5. DOI: 10.1258/acb.2012.012135

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Composition of Ringer's lactate solution 
Image result for ringers lactate contents