The influence of vitamin C on the urine dipstick tests in the clinical specimens: a multicenter study

Lee, Wonmok; Kim, Yu‐Kyung; Chang, Soonhee; Lee, A-Jin; Jeon, Chang‐Ho

doi:10.1002/jcla.22080

Cited by 12 publications

(11 citation statements)

References 8 publications

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“…have detected AA in urine samples of 18.1% of patients of their hospital (group undergoing medical check-ups 23.1%, inpatients 16.3% and outpatients 17.6%). 20 These results indicate higher frequency than discovered in our study; however, the threshold for positivity in their study was lower (10 mg/dL) than in ours (20 mg/dL). When AA was detected in clinical urine samples, 42.3%, 10.6%, and 8.2% of the glucose, haemoglobin, and leukocyte esterase urine strip tests were rated as false negative, respectively.…”

Section: Discussioncontrasting

confidence: 71%

Ascorbic acid in urine still compromises urinalysis results

Gabaj¹,

Miler²,

Unić³

et al. 2019

Ann Clin Biochem

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Background The aim of this work was to determine the frequency of ascorbic acid-positive urine samples and to evaluate the potential risk on patient safety. Materials and methods A total of 27,856 samples submitted for urinalysis in previous year were retrospectively analysed from the laboratory information system. Urinalysis was done on Iris IQ200 analyzer using 11-parameter iChem Velocity test strips. Risk analysis combined the impact of potentially erroneous results (due to ascorbic acid interference) on patient safety (severity – S) with their frequency (occurrence – O). Potential risk was identified as high, intermediate and low. Results One thousand one hundred and ninety-nine (4.3%) and 1646 (5.9%) samples were mildly (20 mg/dL, 1+) and highly positive (40 mg/dL, 2+) for ascorbic acid, respectively. Severity (S1 to S5) was assigned to four possible errors: false-negative glucose (U-Glc: S2), blood (U-Hb: S5), nitrite (U-Nit: S4) and bilirubin (U-Bil: S1). Based on the frequency of errors, occurrence was categorized as: O2 for U-Glc, and O3 for U-Bil, U-Nit and U-Hb. The risk analysis matrix revealed that false-negative U-Hb was associated with potentially high risk, false-negative U-Nit with intermediate risk, while false-negative U-Glc and U-Bil were associated with low risk on patient safety. Conclusions Positive ascorbic acid can cause potentially high risk for patient safety by missing positive blood in urine.

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Section: Discussioncontrasting

confidence: 71%

Ascorbic acid in urine still compromises urinalysis results

Gabaj¹,

Miler²,

Unić³

et al. 2019

Ann Clin Biochem

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“…Ascorbic acid (vitamin C) is frequently found in clinical urine samples and can interfere with the dipstick results . Previous studies have demonstrated that even modest ingestion of vitamin C supplements (350‐1000 mg/d) can cause high concentration of vitamin C in urine which interferes with dipstick determination of glucose and hemoglobin.…”

Section: Discussionmentioning

confidence: 99%

“…Moreover, all subjects who ingested a dose of 350 to 1000 mg of vitamin C per day had concentrations of 25 mg/dL or more of vitamin C in urine . Most of the studies which investigated ascorbic acid impact on urinalysis were performed 10‐20 years ago, which makes our investigation even more important.…”

Section: Discussionmentioning

confidence: 99%

Ascorbic acid—A black hole of urine chemistry screening

Unić

Gabaj

Miler

et al. 2018

Clinical Laboratory Analysis

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“…Diets rich in fruit and vegetables have linked with a reduced risk of chronic disease (Woodside et al, 2017). For healthy, pregnant women need to consume amounts of fruits and vegetables every day, which happen to contain lots of vitamin C. That's why our data showed that the incidence of urinary vitamin C was 27.7% of 34,279 urine samples, which was higher than 18.1% of 5,006 routine urinalysis specimens (Lee et al, 2017). Vitamin C's impact in chemical tests is widespread, not only in urine chemical tests but also in serum biochemical tests.…”

Section: Discussionmentioning

confidence: 67%

“…Though Wonmok Lee etc. (Lee et al, 2017) showed that vitamin C interferes with hemoglobin and leukocyte esterase results. Vitamin C can cause the urine dipstick result was two or more grades lower than the urine sediment result.…”

Section: Discussionmentioning

confidence: 99%

Can we reduce the interference of vitamin C and PH in urinalysis?

et al. 2022

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Urinalysis is often interfered by vitamin C and PH. This study was to evaluate the interference of vitamin C and PH in urinalysis, and minimize the risk to make the effective communication. 732 leftover urine samples in which the concentration of vitamin C was 0.0 mmol/L and either of the test-strip results (Glucose, Blood, Bilirubin, Leucocyte, Nitrite, Protein, Ketone) was positive that were collected. The interference test checked out using these leftover urine samples. When the chemical protein module was positive, the sulfosalicylic acid test performed to confirm the positive results. About 27% of urine samples were vitamin C positive. Adequate vitamin C would interfere with the chemical result of GLU, BIL, and BLD, but not KET, PRO, WBC, NIT (p-value < 0.05). False-positive protein occurred at any samples, but higher when urine PH is greater than or equal to 8.0. In summary, to minimize the risk of vitamin C and PH in urinalysis, the laboratory should pay more attention to its conditions. Also, do more to help guarantee the accuracy of the urinalysis results and to give more comments to doctors to achieve effective communication.

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The influence of vitamin C on the urine dipstick tests in the clinical specimens: a multicenter study

Cited by 12 publications

References 8 publications

Ascorbic acid in urine still compromises urinalysis results

Ascorbic acid in urine still compromises urinalysis results

Ascorbic acid—A black hole of urine chemistry screening

Can we reduce the interference of vitamin C and PH in urinalysis?

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