Saliva analysis for monitoring dialysis and renal function

Qualitative and Quantitative Mass Spectrometry in Salivary Metabolomics and Proteomics

The metabolomics and proteomics analysis of saliva, an excellent biofluid that is a rich source of biological compounds, allows for the safe and frequent screening of drugs, their metabolites, and molecular biomarkers of various diseases. One of the most frequently used analytical methods in saliva analysis is liquid chromatography coupled with mass spectrometry (LC-MS) and tandem mass spectrometry. The low ionisation efficiency of some compounds and a complex matrix makes their identification by MS difficult. Furthermore, quantitative analysis by LC-MS frequently cannot be performed without isotopically labelled standards, which usually have to be specially synthesised. This review presented reports on qualitative and quantitative approaches in salivary metabolomics and proteomics. The purpose of this manuscript was to present the challenges, advances, and future prospects of mass spectrometry, both in the analysis of salivary metabolites and proteins. The presented review should appeal to those interested in the recent advances and trends in qualitative and quantitative mass spectrometry in salivary metabolomics and proteomics, which may facilitate a diagnostic accuracy, the evaluation of treatment efficacy, the early diagnosis of disease, and a forensic investigation of some unapproved drugs for any medical or dietary administration.

A multi-herd study shows that saliva is more than a reflection of serum biomarkers in pigs

This study evaluates if biomarkers of porcine health status in saliva samples is a mere reflection of serum to detect disease in pigs under field conditions. Four farms from the same commercial company were included to obtain samples from animals with different pathological conditions. A total of 10 healthy animals and 10-15 animals from each farm with clinical symptoms of the disease were sampled for paired saliva and blood during a veterinary clinical visit. The biomarker panel included acute-phase proteins (APPs), C-reactive protein (CRP), haptoglobin (Hp), an inflammatory marker, adenosine deaminase (ADA), the total antioxidant capacity (TAC), the levels of essential trace elements, copper (Cu) and zinc (Zn), and the measurement of the total protein content (TP). After detailed statistical analysis, the results showed that saliva could replace serum for APP measurements since a good agreement has been observed between the concentrations of APPs in both body fluids. For any other biomarker, no agreement between the concentrations quantified in serum and saliva samples was observed visually. However, salivary ADA and TP concentrations were statistically significantly higher in the diseased, whereas the statistical tests with serum concentrations were inconclusive. Furthermore, greater differentiation between healthy and diseased animals could be observed when the distribution of biomarkers was analysed in saliva than in other serum samples. The diagnostic power to discriminate between healthy and diseased pigs is similar in saliva and in serum samples. Preliminary regression models may offer an optimal combination of biomarkers for disease detection in saliva (Hp, CRP, and TAC) and serum (Hp, CRP, and Cu), which demands less labour, sample, and financial cost for saliva determinations. The contradictory results observed for TAC, Cu, and Zn levels between body fluids indicate a need for further studies. To sum up, saliva-based biomarkers instead of serum-based biomarkers could contribute to more efficient detection of diseased animals.

Oral health, organic and inorganic saliva composition of men with Schizophrenia: Case-control study

BACKGROUND

Schizophrenia (SCZ) presents complex challenges related to diagnosis and clinical monitoring. The study of conditions associated with SCZ can be facilitated by using potential markers and patterns that provide information to support the diagnosis and oral health.

METHODS

The salivary composition of patients diagnosed with SCZ (n = 50) was evaluated and compared to the control (n = 50). Saliva samples from male patients were collected and clinical parameters were evaluated. The concentration of total proteins and amylase were determined and salivary macro- and microelements were quantified by ICP OES and ICP-MS. Exploratory data analysis based on artificial intelligence tools was used in the investigation.

RESULTS

There was a significant increase in the salivary concentrations of Al, Fe, Li, Mg, Na, and V, higher prevalence of caries (p < 0.001), periodontal disease (p < 0.001), and reduced salivary flow rate (p = 0.019) in SCZ patients. Also, samples were grouped into six clusters. As, Co, Cr, Cu, Mn, Mo, Ni, Se, and Sr were correlated with each other, while Fe, K, Li, Ti, and V showed the highest concentrations in the samples distributed in the clusters with the highest association between SZC patients and controls.

CONCLUSIONS

The results obtained indicate changes in salivary flow, organic composition, and levels of macro- and microelements in SCZ patients. Salivary concentrations of Fe, Mg, and Na may be related to oral conditions, higher prevalence of caries, and periodontal disease. The exploratory analysis showed different patterns in the salivary composition of SCZ patients impacted by associations between oral health conditions and the use of medications. Future studies are encouraged to confirm the results investigated in this study.

Selected salivary parameters in children with idiopathic nephrotic syndrome: a preliminary study

Background

Disturbances in the levels of serum constituents occurring in chronic renal diseases can be reflected in the saliva composition. The aim of this study was to assess some selected salivary components in children suffering from idiopathic steroid-sensitive nephrotic syndrome (iNS).

Methods

A case–control study was performed on iNS and healthy participants. In unstimulated mixed saliva, pH, buffer capacity, total protein, α-amylase, peroxidase, calcium, magnesium, inorganic phosphate, fluoride, urea, uric acid and salivary flow rate were measured. Oral condition was assessed using dmft, DMFT, API and GI indices, usage of fluoride specimens and frequency of tooth brushing. Statistical analysis was performed by Shapiro–Wilk, Brown-Forsythe, Student’s t, ANOVA, Tukey’s and Pearson’s chi-square tests, Pearson’s and Spearman’s correlations, logistic regression and receiver operating characteristic (ROC) curve analysis.

Results

The study involved 94 participants of both genders aged 4–17 (47 cases in relapse or remission phase of iNS and 47 controls) who were treated in the clinic of pediatric nephrology or outpatient dental clinic. Neither group differed in the number of caries-affected primary and permanent teeth, gingival condition or use of fluoride specimens. The iNS group presented lower levels of magnesium (0.41 ± 0.34 vs. 0.60 ± 0.38 mg/dL, P < 0.05) and fluoride (0.15 ± 0.10 vs. 0.21 ± 0.10 ppm, P < 0.01) and higher contents of urea (35.19 ± 15.55 vs. 25.21 ± 10.78 mg/dL, P < 0.01) and uric acid (2.90 ± 1.23 vs. 2.34 ± 1.04 mg/dL, P < 0.05) than the controls. In the iNS participants with relapse, a higher peroxidase activity and lower magnesium content than in the remission phase were found. ROC analysis showed a weak discriminatory power of these salivary constituents for the differentiation of participants with and without disease (accuracy from 66.0 to 67.0%, area under the ROC curve (AUC) from 0.638 to 0.682) and the relapse and remission phases (accuracy 70.2% and 68.1% and AUC 0.717 and 0.675, respectively).

Conclusions

Levels of urea, uric acid, magnesium and fluoride in saliva can be associated with the course of iNS. Salivary levels of peroxidase and magnesium can be related to the phase of the disease. However, the measurements of these parameters cannot be useful as a noninvasive tool in diagnosing iNS and the phase of the disease.

A fluorescence sandwich immunoassay for the real-time continuous detection of glucose and insulin in live animals

Biosensors that continuously measure circulating biomolecules in real time could provide insights into the health status of patients and their response to therapeutics. But biosensors for the continuous real-time monitoring of analytes in vivo have only reached nanomolar sensitivity and can measure only a handful of molecules, such as glucose and blood oxygen. Here we show that multiple analytes can be continuously and simultaneously measured with picomolar sensitivity and sub-second resolution via the integration of aptamers and antibodies into a bead-based fluorescence sandwich immunoassay implemented in a custom microfluidic chip. After an incubation time of 30 s, bead fluorescence is measured using a high-speed camera under spatially multiplexed two-colour laser illumination. We used the assay for continuous quantification of glucose and insulin concentrations in the blood of live diabetic rats to resolve inter-animal differences in the pharmacokinetic response to insulin as well as discriminate pharmacokinetic profiles from different insulin formulations. The assay can be readily modified to continuously and simultaneously measure other blood analytes in vivo.

The use of bacterial DNA from saliva for the detection of GAS pharyngitis

Background

Acute tonsillitis is a very common medical condition. Despite different methods of detection, all tests are based on GAS sampling using a throat swab. However, obtaining the swab can elicit vomiting and is often accompanied by fear and apprehension in children. The aim of this study was to find a non-invasive method for the detection of GAS pharyngitis.

Methods

A classic throat swab was obtained for culture, and a saliva sample was taken from 100 subjects recruited from Meuhedet Health Care Organization clinic. Real time PCR was performed to detect GAS dnaseB specific gene in the saliva samples.

Results

56% of the throat cultures and 48% of the PCR samples were positive for GAS. The overall sensitivity and specificity of the saliva PCR method was 79% and 91% respectively; NPV and PPV were 77% and 92% respectively. When excluding patients who presented on the first day of fever, sensitivity and specificity increased to 90% and 100% respectively. No other anamnestic or clinical findings increased the yield of the test.

Conclusion

Saliva-based PCR amplification of GAS DNA method is effective in detection of GAS pharyngitis. Further studies are needed to achieve detection rates to replace the traditional throat swab-based approach.

Association of mRNA Levels of IL6, MMP-8, GSS in Saliva and Pyelonephritis in Children

Nowadays, saliva is a subject of growing scientific interest because of its definite advantages as diagnostic medium. The aim of our study was to investigate the diagnostic potential and reliability of messenger RNAs (mRNAs) of selected genes—interleukin-6 (IL-6), matrix metalloproteinase-8 (MMP-8) and glutathione synthetase (GSS)—as salivary markers in children with diagnosed pyelonephritis and to correlate their levels with typical urine para-clinical indicators of the disease. Analysis of the mRNA levels for IL-6, MMP-8 and GSS in 28 children hospitalized with the diagnosis of pyelonephritis was conducted applying the method of quantitative reverse transcription polymerase chain reaction (RT-qPCR). In the study group (n = 28), IL-6 mRNA levels demonstrated 64-fold increase (p < 0.001). MMP-8 and GSS mRNA levels were increased in 12 samples in patients with pyelonephritis 3.27 (p < 0.01) and 1.94 (p < 0.001) times, respectively. We found a strong and significant correlation (p < 0.001) between the investigated mRNA for IL-6 and MMP-8, IL-6 and GSS, MMP-8 and GSS. Moderate degree of correlation was established between IL-6 and the typical para-clinical indicator of leucocytes (0.43, p < 0.05) and between GSS and leucocytes (0.54, p < 0.01). Salivary IL-6, MMP-8 and GSS mRNA levels in combination with urine test analysis could be useful diagnostic tool for the very distributed disorder of pyelonephritis in childhood.

Preliminary evaluation of a salivary urea test strip method for use in dogs

BACKGROUND

Salivary urea concentrations correlate with serum urea concentrations in dogs and humans. Salivary urea concentrations can now be determined semi-quantitatively using a salivary urea test strip method that has been validated for use in humans.

OBJECTIVES

We aimed to evaluate the repeatability of the salivary urea test strip score, and the correlation between the salivary urea test strip scores and serum urea concentrations in dogs.

METHODS

Intra-run and inter-run variabilities were determined (n = 10 in triplicate). Correlations between salivary urea test strip scores and serum urea concentrations in dogs were assessed using the Spearman's correlation coefficient. Receiver operator curve analysis was used to evaluate the diagnostic performance of the salivary urea test strip score to identify dogs with serum urea concentration >7.4 mmol/L (upper limit of laboratory RI).

RESULTS

The intra-run repeatability was good (28/30 concordant results) whereas the inter-run repeatability was moderate (23/30 concordant results). Salivary and serum urea concentrations showed a moderately positive correlation (r_s  = .63, n = 33; P < .0001). A salivary urea test strip score ≥4 was 57% sensitive and 96% specific for detecting a serum urea concentration >7.4 mmol/L.

CONCLUSIONS

Uremia can be detected using salivary urea test strips in dogs. Based on our preliminary data, salivary urea test strip scores of 1 or 2 might exclude clinically relevant uremia in most cases; however, it is recommended that the salivary urea test be repeated in dogs with a test strip score of 3. Dogs with a salivary urea test strip score of ≥4 would likely require additional investigations.

Modern creatinine (Bio)sensing: Challenges of point-of-care platforms

The importance of knowing creatinine levels in the human body is related to the possible association with renal, muscular and thyroid dysfunction. Thus, the accurate detection of creatinine may indirectly provide information surrounding those functional processes, therefore contributing to the management of the health status of the individual and early diagnosis of acute diseases. The questions at this point are: to what extent is creatinine information clinically relevant?; and do modern creatinine (bio)sensing strategies fulfil the real needs of healthcare applications? The present review addresses these questions by means of a deep analysis of the creatinine sensors reported in the literature over the last five years. There is a wide range of techniques for detecting creatinine, most of them based on optical readouts (20 of the 33 papers collected in this review). However, the use of electrochemical techniques (13 of the 33 papers) is recently emerging in alignment with the search for a definitive and trustworthy creatinine detection at the point-of-care level. In this sense, biosensors (7 of the 33 papers) are being established as the most promising alternative over the years. While creatinine levels in the blood seem to provide better information about patient status, none of the reported sensors display adequate selectivity in such a complex matrix. In contrast, the analysis of other types of biological samples (e.g., saliva and urine) seems to be more viable in terms of simplicity, cross-selectivity and (bio)fouling, besides the fact that its extraction does not disturb individual's well-being. Consequently, simple tests may likely be used for the initial check of the individual in routine analysis, and then, more accurate blood detection of creatinine could be necessary to provide a more genuine diagnosis and/or support the corresponding decision-making by the physician. Herein, we provide a critical discussion of the advantages of current methods of (bio)sensing of creatinine, as well as an overview of the drawbacks that impede their definitive point-of-care establishment.

Microfluidic paper-based analytical devices for potential use in quantitative and direct detection of disease biomarkers in clinical analysis

Clinicians, working in the health-care diagnostic systems of developing countries, currently face the challenges of rising costs, increased number of patient visits, and limited resources. A significant trend is using low-cost substrates to develop microfluidic devices for diagnostic purposes. Various fabrication techniques, materials, and detection methods have been explored to develop these devices. Microfluidic paper-based analytical devices (μPADs) have gained attention for sensing multiplex analytes, confirming diagnostic test results, rapid sample analysis, and reducing the volume of samples and analytical reagents. μPADs, which can provide accurate and reliable direct measurement without sample pretreatment, can reduce patient medical burden and yield rapid test results, aiding physicians in choosing appropriate treatment. The objectives of this review are to provide an overview of the strategies used for developing paper-based sensors with enhanced analytical performances and to discuss the current challenges, limitations, advantages, disadvantages, and future prospects of paper-based microfluidic platforms in clinical diagnostics. μPADs, with validated and justified analytical performances, can potentially improve the quality of life by providing inexpensive, rapid, portable, biodegradable, and reliable diagnostics.

Low-cost bioanalysis on paper-based and its hybrid microfluidic platforms

Low-cost assays have broad applications ranging from human health diagnostics and food safety inspection to environmental analysis. Hence, low-cost assays are especially attractive for rural areas and developing countries, where financial resources are limited. Recently, paper-based microfluidic devices have emerged as a low-cost platform which greatly accelerates the point of care (POC) analysis in low-resource settings. This paper reviews recent advances of low-cost bioanalysis on paper-based microfluidic platforms, including fully paper-based and paper hybrid microfluidic platforms. In this review paper, we first summarized the fabrication techniques of fully paper-based microfluidic platforms, followed with their applications in human health diagnostics and food safety analysis. Then we highlighted paper hybrid microfluidic platforms and their applications, because hybrid platforms could draw benefits from multiple device substrates. Finally, we discussed the current limitations and perspective trends of paper-based microfluidic platforms for low-cost assays.

Salivary markers in patients with chronic renal failure

INTRODUCTION

Chronic renal failure (CRF) is a progressive loss of renal function over a period of months or years. The major function of the kidneys is the removal of metabolic waste products, electrolytes and water. When this function is impaired, systemic changes, oral complications and alterations in salivary composition may occur.

OBJECTIVE

This study aimed to compare the levels of immunological and inflammatory components in the saliva samples from patients that undergo to hemodialysis treatment (HD), without HD and control.

DESIGN

This study evaluated IgA, IgG, C reactive protein (CRP) and nitric oxide (NO) in saliva samples from 119 patients, who were divided into the control group (C), chronic renal failure (CRF) patient group and CRF patients on hemodialysis treatment (HD) group. IgA and IgG levels were analyzed by ELISA. Nitric oxide levels were determined indirectly by the nitrite concentration using Griess reagent; CRP by agglutination tests; and total proteins, by Bradford assay.

RESULTS

The HD group showed significantly higher levels of IgG, IgA and CRP compared with the control and CRF groups. The CRF group presented the same amounts of IgG, IgA and CRP as the C group but significantly higher levels of NO similar to the HD group.

CONCLUSION

Renal disease, particularly hemodialysis treatment during renal disease, seems to alter salivary immunological and inflammatory components. Thus, analyzing the levels of IgA, IgG, NO and CRP in saliva may be beneficial for monitoring renal disease.

Salivary alkaline phosphatase and calcium in caries-active type II diabetes mellitus patients: An in vivo study

Background:

Diabetes Mellitus is a metabolic syndrome, affecting the oral health in various ways with dental caries being one of the most common problems encountered. Saliva is one of the most abundant secretions in the human body with a variety of natural protective and defence molecules bathing the oral cavity maintaining equilibrium. Its collection is easy and non-invasive.

Aims:

To compare and evaluate salivary alkaline phosphatase levels and calcium ion levels between caries active type II diabetes mellitus patients and non-diabetics.

Materials and Methods:

This study was carried out on caries-active age and gender matched 60 non-diabetic and 60 patients with known Type II diabetes mellitus subjects of age group 25-50 years with DMFT index >10. Saliva sample was collected to analyse for alkaline phosphatase enzyme and concentration of calcium ions using Agappe kits.

Statistical Analysis:

Student ‘t’ test was used to correlate the salivary electrolyte concentration in non- diabetic and diabetic patients with dental caries. A ‘P’ value of 0.05 or less was considered significant. Results are presented as mean ± standard deviation (X ± SD).

Results:

The alkaline phosphatase (ALP) activity in saliva was higher in diabetic patients when compared to that of non-diabetic patients with salivary calcium ions were significantly higher in non-diabetic individuals.

Conclusion:

Diabetes Mellitus patients are more prone to dental caries, hence require intervention to improve the quality of saliva.

Analysis of blood and salivary urea levels in patients undergoing haemodialysis and kidney transplant

AIMS AND OBJECTIVES

To determine correlation between the Salivary Urea levels with that of Blood Urea levels.

MATERIALS AND METHODS

Subjects were selected from patients undergoing haemodialysis and patients who had underwent kidney transplantation at Ashwini Hospitals Guntur. The study comprised of 45 patients, of which Haemodialysis group (HD) with 20 patients, Transplant (T) group with 15 patients and 10 patients in control group. Samples of blood and saliva were taken from all the patients to assess the Blood Urea Nitrogen (BUN) and Salivary Urea (SU) levels respectively under strict aseptic precautions. Blood was collected just prior to the dialysis in HD group and in renal transplant (T) patients during their review visit. Informed consent was taken from patients and ethical committee approval taken.

RESULTS

There was a statistically significant difference between Blood Urea and Salivary Urea levels in the HD and T group (p<0.05). There was a statistically significant difference between T and Control group with respect to Blood Urea and Salivary Urea levels. The salivary urea levels are slightly higher than blood urea levels in all the study groups.

CONCLUSION

The salivary urea tests can be used in place of blood tests as a non invasive diagnostic tool. Thus, preventing the unnecessary and periodic withdraw of blood which is not only cumbersome but also leads to recurrent infections.

Salivary creatinine estimation as an alternative to serum creatinine in chronic kidney disease patients

Context. Sampling blood for serum analysis is an invasive procedure. A noninvasive alternative would be beneficial to patients and health care professionals. Aim. To correlate serum and salivary creatinine levels and evaluate the role of saliva as a noninvasive alternative to serum for creatinine estimation in chronic kidney disease patients. Study Design. Case-control study. Methods. Blood and saliva samples were collected from 37 healthy individuals and 105 chronic kidney disease patients. Serum and salivary creatinine levels were estimated using automatic analyser. Statistical Analysis. The serum and salivary creatinine levels between controls and cases were compared using t-test. Correlation between serum and salivary creatinine was obtained in controls and cases using Pearson correlation coefficient. Receiver operating characteristic analysis was done to assess the diagnostic performance of salivary creatinine. Cut-off values were established for salivary creatinine. Results. Serum and salivary creatinine levels were significantly higher in CKD patients than controls. The correlation was negative in controls and positive in cases. Area under the curve for salivary creatinine was found to be 0.967. A cut-off value of 0.2 mg/dL gave a sensitivity of 97.1% and specificity of 86.5%. Conclusion. Saliva can be used as a noninvasive alternative to serum for creatinine estimation.

Salivary diagnostics: a brief review

Early detection of disease plays a crucial role for treatment planning and prognosis. Saliva has great potential as a diagnostic fluid and offers advantage over serum and other biological fluids by an economic and noninvasive collection method for monitoring of systemic health and disease progression. The plethora of components in this fluid can act as biomarkers for diagnosis of various systemic and local diseases. In this review paper, we have emphasized the role of salivary biomarkers as diagnostic tools.

Printed two-dimensional micro-zone plates for chemical analysis and ELISA

In this study we report a new concept of printing low-cost two-dimensional micro-zone plates for chemical and biochemical assays and ELISA. It is different from the concept of forming multi-zone micro-zones on paper by hydrophobic barriers first reported by Yagoda. Instead, the desired multi-zone micro-zone pattern was first printed using a UV-curable varnish onto a polymer film; then fine powders of cellulose or other materials were applied onto the uncured varnish, allowing the powder to stick to the varnish layer. After UV-curing, the powder particles were fixed by the cured varnish, leading to the formation of porous, water absorbing micro-zones on the polymer film. This type of micro-zone plate has the required liquid handling capacity for a variety of low-volume and portable two-dimensional plates for chemical, biochemical assays and ELISA. By suitably spacing porous micro-zones on a non-porous substrate, this type of plate eliminates inter-zone sample leaking. Rapid colorimetric analysis of the results can be performed using a portable battery-powered colour densitometer or a desktop scanner. By introducing a refractive-index-matching liquid into the micro-zones, the plate can be easily analyzed using transmission instruments. A major advantage of this plate fabrication method is that it enables the printing of different powders or functionalized powders to form micro-zones on a same plate, potentially allowing certain more difficult functionalization of materials to be performed before printing. We demonstrate the assaying performance of the plates using an analytical system that aims to clarify the analytical interference between NO(2)(-) and uric acid (UA) in the analysis of samples where both chemical species are present. We also show that ELISA assays can be performed using this type of plates.

Saliva as a diagnostic fluid

Salivary diagnostics is a dynamic and emerging field utilizing nanotechnology and molecular diagnostics to aid in the diagnosis of oral and systemic diseases. In this article the author critically reviews the latest advances using oral biomarkers for disease detection. The use of oral fluids is broadening perspectives in clinical diagnosis, disease monitoring, and decision making for patient care. Important elements determining the future possibilities and challenges in this field are also discussed.

Biological microdevice with fluidic acoustic streaming for measuring uric acid in human saliva

The healthcare system requires new devices for a rapid monitoring of a patient in order to improve the diagnosis and treatment of various diseases. Accordingly, new biomedical devices are being developed. In this paper, a fully-integrated biological microdevice for uric acid analysis in human saliva is presented. It is based on optical spectrophotometric measurements and incorporates a mixture system based on acoustic streaming, that enhances the fluids reaction due to both heating and agitation generated by this effect. Acoustic streaming is provided by a piezoelectric beta-PVDF film deposited underneath the microfluidic die of the device. Further, it incorporates the electronics for the detection, readout, data processing and signal actuation. Experimental results proved that acoustic streaming based on this piezoelectric polymer is advantageous and reduces in 55% the time required to obtain the analysis results.

Thread as a versatile material for low-cost microfluidic diagnostics

This paper describes a new and simple concept for fabricating low-cost, low-volume, easy-to-use microfluidic devices using threads. A thread can transport liquid via capillary wicking without the need of a barrier; as it is stainable, it is also a desirable material for displaying colorimetric results. When used in sewing, threads have 3D passageways in sewed materials. The wicking property and flexibility of thread make it particularly suitable to fabricate 3D microfluidic devices. Threads can also be used with other materials (e.g., paper) to make microfluidic devices for rapid qualitative or semiquantitative analysis. These thread-based and thread-paper-based devices have potential applications in human health diagnostics, environmental monitoring, and food safety analysis, and are particularly appropriate for the developing world or remote areas, because of their relatively low fabrication costs.

Quantitative biomarker assay with microfluidic paper-based analytical devices

This article describes the use of microfluidic paper-based analytical devices (muPADs) to perform quantitative chemical assays with internal standards. MicroPADs are well-suited for colorimetric biochemical assays; however, errors can be introduced from the background color of the paper due to batch difference and age, and from color measurement devices. To reduce errors from these sources, a series of standard analyte solutions and the sample solution are assayed on a single device with multiple detection zones simultaneously; an analyte concentration calibration curve can thus be established from the standards. Since the muPAD design allows the colorimetric measurements of the standards and the sample to be conducted simultaneously and under the same condition, errors from the above sources can be minimized. The analytical approach reported in this work shows that muPADs can perform quantitative chemical analysis at very low cost.