Blue-green discoloration of urine and false nephrotic range proteinuria at dipstick urinalysis

Poloni, José Antônio Tesser; Sassi, Marina Gomes de Moraes; Oliveira, Tiago Franco de; Rotta, Liane Nanci; Perazella, Mark A.

doi:10.1016/j.cca.2018.03.036

Cited by 5 publications

(2 citation statements)

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“…Unfortunately, chemical tests are often interfered with by lots of factors, such as vitamin C and PH (Unic et al, 2018). To provide accurate reports to doctors, laboratory scientists should recognize and reduce false positive or false negative results (Poloni et al, 2018). In our department, amounts of DIRUI dipsticks (FUS-12MA II) consume every day.…”

Section: Introductionmentioning

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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Section: Introductionmentioning

confidence: 99%

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

et al. 2022

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“…Presence of various exogenous or endogenous substances can interfere with the measurement and lead to false-positive or false-negative results. 3,4 Interference of ascorbic acid (AA) on urine test strip analysis has been known for many years. 5 AA is a strong antioxidant which can cause false-negative results for analytes that are detected by peroxidase reaction.…”

Section: Introductionmentioning

confidence: 99%

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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Methenamine/methylthioninium chloride

2018

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Blue-green discoloration of urine and false nephrotic range proteinuria at dipstick urinalysis

Cited by 5 publications

References 0 publications

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

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

Ascorbic acid in urine still compromises urinalysis results

Methenamine/methylthioninium chloride

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