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
This paper 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.
Conclusion of Paper
Ascorbic acid significantly interfered with the quantification of chloride, calcium, and magnesium, and glucose significantly interfered with the quantification of calcium, total protein, magnesium, creatinine, urea, and uric acid; 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.
Studies
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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
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