The interference and elimination of nitrite on determination of total urinary protein by Pyrogallol Red–Molybdate method

IF 1.7 Q3 MEDICAL LABORATORY TECHNOLOGY Practical Laboratory Medicine Pub Date : 2024-10-15 DOI:10.1016/j.plabm.2024.e00436

Shijian Fan , Jiaqing Liu , Yu Wei , Jie Yao , Juan Cheng , Yang Tong , Qiang Zhou , Yuanhong Xu

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Abstract

Background

Some urine samples showed negative values of total urinary protein by Pyrogallol red–molybdate (PRM) method. Interestingly, these samples showed notably high levels of nitrite in the urine dipstick test.

Methods

A total of 120 urine samples were collected and categorized into four groups (0 - < 100, 100-<500, 500-<1000, ≥1000 mg/L) based on total urinary protein concentration. Various concentrations of nitrite (2, 10, 50, 100, and 200 mg/L) were added to urine samples to investigate potential interference of nitrite in total urinary protein measurement by the PRM method. Additionally, different concentrations of L-ascorbic acid (100, 500, 1000, and 2000 mg/L) were added to urine-nitrite mixtures to explore the possibility of reversing the interference effects.

Results

2 mg/L nitrite had no impact on the test results.10 mg/L nitrite only showed significant effects on the detection results among the groups with 0 - < 100 and 100-<500 mg/L (P < 0.05). 200 mg/L nitrite caused a noticeable decrease in the urinary protein detection results of the four groups (0 - < 100, 100-<500, 500-<1000, ≥1000 mg/L), and the concentrations were reduced to 2.7 %, 26.85 %, 75.22 %, and 89.33 % of their original levels, respectively. 500 mg/L L-ascorbic acid effectively eliminated the interference from 200 mg/L nitrite and almost had no effect on detection.

Conclusions

Nitrite had negative effect on the detection of total urinary protein by PRM method and L-ascorbic acid was effective in counteracting the interference caused by nitrite.

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焦红-钼酸盐法测定尿总蛋白时亚硝酸盐的干扰与消除

背景部分尿样经焦聚醇红钼酸盐（PRM）法检测显示尿总蛋白呈阴性。方法共收集了 120 份尿液样本，并根据尿液总蛋白浓度分为四组（0 - 100、100-500、500-1000、≥1000 mg/L）。在尿样中加入不同浓度的亚硝酸盐（2、10、50、100 和 200 mg/L），以研究亚硝酸盐对 PRM 方法测定尿蛋白总量的潜在干扰。结果2 毫克/升亚硝酸盐对检测结果没有影响。10 毫克/升亚硝酸盐只对 0 - < 100 和 100 - < 500 毫克/升组的检测结果有显著影响（P < 0.05）。200 mg/L 亚硝酸盐使四组（0 - <100、100-<500、500-<1000、≥1000 mg/L）的尿蛋白检测结果明显下降，浓度分别降至原来的 2.7 %、26.85 %、75.22 % 和 89.33 %。结论亚硝酸盐对 PRM 法检测尿总蛋白有负面影响，L-抗坏血酸能有效抵消亚硝酸盐的干扰。

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来源期刊

Practical Laboratory Medicine Health Professions-Radiological and Ultrasound Technology

CiteScore

3.50

自引率

0.00%

发文量

审稿时长

7 weeks

期刊介绍： Practical Laboratory Medicine is a high-quality, peer-reviewed, international open-access journal publishing original research, new methods and critical evaluations, case reports and short papers in the fields of clinical chemistry and laboratory medicine. The objective of the journal is to provide practical information of immediate relevance to workers in clinical laboratories. The primary scope of the journal covers clinical chemistry, hematology, molecular biology and genetics relevant to laboratory medicine, microbiology, immunology, therapeutic drug monitoring and toxicology, laboratory management and informatics. We welcome papers which describe critical evaluations of biomarkers and their role in the diagnosis and treatment of clinically significant disease, validation of commercial and in-house IVD methods, method comparisons, interference reports, the development of new reagents and reference materials, reference range studies and regulatory compliance reports. Manuscripts describing the development of new methods applicable to laboratory medicine (including point-of-care testing) are particularly encouraged, even if preliminary or small scale.