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Ascorbic acid and glucose can cause significant interference on quantitative measurement of biochemistry analytes in urine.

Author(s): Mašković S, Nikolac Gabaj N

Publication: Lab Med, 2024, Vol. , Page

PubMed ID: 39550214 PubMed Review Paper? No

Purpose of Paper

Conclusion of Paper

Studies

1. Study Purpose

   This study investigated if elevated levels of ascorbic acid or glucose interfere with quantification of common biochemical analytes by spiking aliquots of a single pooled urine specimen with 0.2-5.0 g/L ascorbic acid or 10-50 mM glucose. Two surplus 24 h urine specimens (diagnosis not specified) were pooled and aliquoted and stored at -20°C. Aliquots (10 mL) were spiked with 0, 0.2, 0.4, 0.5, 1, 2, and 5 g/L ascorbic acid or 0, 10, 20, 30, 40, 50, and 60 mmol/L glucose. Levels of calcium, inorganic phosphate, creatinine, amylase activity, magnesium, urea, uric acid, sodium, potassium, and chloride were quantified in duplicate using an Abbott ARCHITECT c8000 analyzer. Interference was considered clinically significant when the deviation exceeded the long-term analytical coefficients of variance.

   Summary of Findings:

   Ascorbic acid significantly interfered with the quantification of chloride, calcium, and magnesium in urine specimens, as bias exceeded the acceptance criteria when urine was spiked with ≥1 g/L, 0.5 or 2.0 g/L and 0.2 or 2.0 g/L ascorbic acid, respectively. Glucose significantly interfered with the quantification of calcium and total protein when urine was spiked with either 10 mM or ≥30 mM glucose (but not 20 mM), mag­nesium when urine was spiked with either 10 mM or ≥50 mM glucose, creatinine when urine was spiked with either 30 mM or ≥50 mM (but not 40 mM) glucose, urea when urine was spiked with either 20 mM or ≥50 mM glucose, and uric acid when urine was spiked with ≥350 mM glucose. Only glucose’s interference with uric acid quantification was linear with glucose concentration. High, spiked-in levels of ascorbic acid or glucose did not interfere with the quantification of albumin, amylase, sodium, potassium, or phosphate. The author advised caution when analyzing urine with high concentrations of ascorbic acid or glucose.

   Biospecimens

   • Bodily Fluid - Urine

   Preservative Types

   • Frozen

   Diagnoses:

   • Not specified

   Platform:

   Analyte	Technology Platform
   Electrolyte/Metal	Clinical chemistry/auto analyzer
   Small molecule	Clinical chemistry/auto analyzer
   Protein	Clinical chemistry/auto analyzer

   Pre-analytical Factors:

   Classification	Pre-analytical Factor	Value(s)
   Biospecimen Aliquots and Components	Biospecimen components	Spiked with 0, 0.2, 0.4, 0.5, 1, 2, or 5 g/L ascorbic acid Spiked with 0, 10, 20, 30, 40, 50, or 60 mM glucose

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