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Vitamin C and aberrant electrolyte results.
Qing H Meng1, William C Irwin, Kishore Visvanathan
1Division of Clinical Biochemistry, Department of Pathology and Laboratory Medicine, University of Saskatchewan, Canada. qing.meng@usask.ca
Clinical Chemistry and Laboratory Medicine
|May 19, 2005
Summary
High-dose vitamin C can interfere with electrolyte testing, leading to inaccurate results. This case highlights the importance of considering vitamin C interference in patients with abnormal electrolyte panels.
Area of Science:
- Clinical Chemistry
- Analytical Biochemistry
- Medical Diagnostics
Background:
- Vitamin C (ascorbic acid) is known to interfere with redox-reaction assays.
- Interference of vitamin C with electrolyte measurements has not been previously reported.
- Accurate electrolyte measurement is crucial for patient diagnosis and management.
Observation:
- A 61-year-old female patient with terminal colon cancer presented with anuria and severe, incongruous electrolyte abnormalities (serum sodium 200 mmol/L, potassium 7.0 mmol/L, chloride 50 mmol/L) on the Beckman Synchron LX20 analyzer.
- The patient's clinical presentation (alert, normal vital signs) did not correlate with the critical electrolyte values.
- Electrolyte analysis on different platforms (ABL700, Bayer644) yielded normal results for the same specimen.
Findings:
- Vitamin C administration was identified as the cause of analytical interference in electrolyte assays.
- In vitro testing confirmed that vitamin C causes falsely abnormal electrolyte results on the Beckman Synchron LX20.
- The interference is specific to certain analytical platforms and assay chemistries.
Implications:
- Clinicians should be aware of potential vitamin C-induced analytical interference when interpreting electrolyte results.
- Consideration of vitamin C levels may be necessary in patients with unexplained electrolyte abnormalities.
- This finding necessitates a review of laboratory protocols and diagnostic strategies for electrolyte testing in patients receiving high-dose vitamin C therapy.