Uric Acid

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Overview

Serum-Saliva Correlation r = 0.84
Sensitivity 0.07 mg/dL LOD
Sample Test Volume 10 µL
Recommended Collection Volume >25 µL
Special Considerations

High consumption of alcohol beverages (particularly beer), fructose and diets high in purine-rich foods can alter Uric Acid levels.

Several drugs may alter Uric Acid levels (Moriwaki 2014).

Collection Protocol Download PDF

Description


  1. Galassi FM, Borghi C. (2015). A brief history of uric acid: From gout to cardiovascular risk factor. Eur J Intern Med, 26(5), 373.
  2. Pohanka M. (2014). Alzheimer’s disease and oxidative stress: a review. Curr Med Chem, 21(3), 356-64.
  3. Ames BN, Cathcart R, Schwiers E, Hochstein P. (1981). Uric acid provides an antioxidant defense in humans against oxidant- and radical-caused aging and cancer: a hypothesis. Proc Natl Acad Sci U S A, 78(11):6858-62.
  4. Glantzounis GK, Tsimoyiannis EC, Kappas AM, Galaris DA. (2005). Uric acid and oxidative stress. Curr Pharm Des, 11(32), 4145-51.
  5. Lu N, Dubreuil M, Zhang Y, Neogi T, Rai SK, Ascherio A, et al. (2015). Gout and the risk of Alzheimer's disease: a population-based, BMI-matched cohort study. Ann Rheum Dis, Epub ahead of print.
  6. Lippi G, Montagnana M, Franchini M, Favaloro EJ, Targher G. (2008). The paradoxical relationship between serum uric acid and cardiovascular disease. Clin Chim Acta, 392(1-2), 1-7.
  7. Rees F, Hui M, Doherty M. (2014). Optimizing current treatment of gout. Nat Rev Rheumatol, 10(5), 271-83.
  8. Soukup M, Biesiada I, Henderson A, Idowu B, Rodeback D, Ridpath L, et al. (2012). Salivary uric acid as a noninvasive biomarker of metabolic syndrome. Diabetol Metab Syndr, 4(1), 14.
  9. Xia Y, Peng C, Zhou Z, Cheng P, Sun L, Peng Y, et al. (2012). [Clinical significance of saliva urea, creatinine, and uric acid levels in patients with chronic kidney disease]. Zhong Nan Da Xue Xue Bao Yi Xue Ban, 37(11), 1171-6.
  10. Nunes LA, Brenzikofer R, Macedo DV. (2011). Reference intervals for saliva analytes collected by a standardized method in a physically active population. Clin Biochem, 44(17-18), 1440-4.
  11. Goll RD, Mookerjee BK. (1978). Correlation of biochemical parameters in serum and saliva in chronic azotemic patients and patients on chronic hemodialysis. J Dial, 2(4), 399-44.

​The effects of freeze thaw on most biological measures, regardless of biospecimen type, can be dramatic. Analytes in oral fluid are not distinct or different in this way. As a general rule, multiple freeze-thaws should be avoided.  The most practical way to address this concern is by aliqouting samples after collection. Some analytes are more resistant to freeze thaw than others. We recommend that investigators consult the literature for the analytes of interest. If there is freeze thaw data for a specific biological measure in traditional biospecimens, it is reasonable to assume this would also be true for saliva.

 

​No, but the literature is rather extensive on this subject for several salivary analytes; especially for salivary alpha-amylase and cortisol. We do not track that information internally. 

 

​Salimetrics kits are not plate reader specific. Any plate reader should work with our kits. Each specific kit insert gives the recommended filter(s) and curve fit in the calculation section; Salimetrics recommends a 4 parameter curve fit for most of our kits.

 

​First you have to have a plate reader that can read at duel wavelengths, which most can. Then you set up the plate reader program (protocol) to use the 450nm filter as the primary filter (405nm for alpha-amylase). The secondary filter is then added as specified in the kit instructions. The plate reader program should then automatically subtract the OD readings from the secondary filter from the OD readings of the primary filter and these would then be your ‘corrected’ OD readings, which would be used in the calculation of your data.  (The absorbance readings form a bell shaped curve with the peak at 450nm. What subtracting the secondary OD reading does is subtract any interference (or background ‘noise’) outside the desired wavelength of 450nm.) You can just read at 450nm without correction if your plate reader is a single wavelength reader or you don’t have the proper secondary filter - correction is desirable for the most accurate results, but not necessary to complete the assay.

 

​Salimetrics is familiar with Biotek plate washers as we recommend them. If you have a Biotek plate washer, we can coach you via our technical support team. If you don’t have a Biotek washer we can provide guidance, but you may need to contact your sales representative for specific details.

 

​Performance characteristics for each Salimetrics kit can be found in the kit inserts/protocols online. One of the most important performance characteristics is the specificity of the antibody. You should not see a lot of cross-reactivity with similar compounds to the one you are measuring as this could indicate that you will not get an accurate measurement of the desired analyte.

 

​We have not yet tested our assays under conditions that do not follow the standard kit protocol. If you are unable to follow the assay procedure as written, it is recommended that you validate your results by running a pilot.

 

​The Salimetrics SIgA kit will pick up all forms of IgA, but not the free secretory piece alone. The concentration of IgA in saliva is minimal compared to the very high concentrations of SIgA. The Salimetrics SIgA kit measures both secretory IgA and monomeric IgA; it uses a polyclonal antibody and it is not specific for secretory IgA. It measures monomeric IgA (as found in serum) which accounts for approximately 15% of total IgA in saliva and diffuses into saliva from serum. The other 85% of IgA in saliva is true secretory IgA.  

Cited from; Brandtzaeg P (2007) Do salivary antibodies reliably reflect both mucosal and systemic immunity?  Ann NY Acad Sci 1098: 288-311.  Furthermore, according to Dr. Gleeson; both monomeric and secretory IgA in saliva will contribute to mucosal immunity.

Other good references from Dr. Gleeson;Acute and chronic effects of exercise on markers of mucosal immunity.  Nicolette C Bishop, Michael Gleeson

Frontiers in Bioscience (impact factor: 3.52). 02/2009; 14:4444-56; 19273362

A. K. Blannin, P. J. Robson, N. P. Walsh, A. M. Clark, L. Glennon and M. Gleeson:The effect of exercising to exhaustion at different intensities on saliva immunoglobulin A, protein and electrolyte secretion.Int J Sports Med 19, 546-552 (1998)

doi:10.1055/s-2007-971958  http://dx.doi.org/10.1055/s-2007-971958

 

​No, they are not necessary. However, this raises safety concerns. Saliva is a source of infectious disease. If you are running samples from patients with known infectious diseases, running samples under a biosaftey hood would be recommended. Sometimes samples held at room temperature can develop a strong odor and technicians running these assays may prefer to run such samples under a hood.

 

​It is a known fact that sodium azide is an inhibitor of horseradish peroxidase, which is used in most Salimetrics immunoassay kits. No Salimetrics kits contain sodium azide except alpha-amylase and uric acid in which sodium azide is added as a preservative.  (The alpha-amylase & uric acid kit does not contain horseradish peroxidase.)  According to some salivary assay manufacturers, concentrations of sodium azide < 0.02% do not interfere with peroxidase. Salimetrics has not conducted studies to verify this claim.

WARNING: Sodium Azide is highly toxic to humans and very dangerous for the environment!   

​Salimetrics does not recommend using plate covers for alpha-amylase because it would likely interfere with the plate reads.  

 

​Failure to follow kit procedure and recommendations for saliva collection and sample handling may result in false values. If you are unable to follow the assay procedure as written, it is recommended that you validate your results by running a pilot.

 

On our website we have information that connects each of our assay kits to a range of applications. Given the volume of publications using salivary analytes the amount of information generated is not easy for Salimetrics to maintain internally.

We recommend that you (a) use Pubmed and Psychlit to conduct a literature search. We know that the quality of the literature is higher, with respect to assay technology, starting about 1998. Publications before that time, should be reviewed carefully and (b) contact us via our “ask and expert”. Salimetrics scientists are actively participating in creating this literature and have a wealth of information we are happy to share.

 

​The number of tests that can be conducted for each assay type is noted in each assay’s kit insert (generally 38 samples in duplicate per kit). Divide the number of samples by the number samples that can be done on one plate.  If you are operating in an experienced lab we suggest adding  5% to this figure to accommodate for repeats. If you are just getting started, or have less-experienced operators running the assays, it is wise to include 10% in addition to the number you calculate to enable repeat testing if needed.

 

​Yes, in theory as long as the molecular structure of the analyte is conserved across species, then the assay would perform. Salimetrics cortisol assay has been used with horses, dogs, deer, antelope, fish, sea lions for example. However, the levels of salivary analytes can be very different between species, and some species may not have certain analytes in their saliva. Careful pilot testing should be conducted to verify basic assay performance in non-human species.

 

​The assay formats differ for different analytes.  In the kit insert, the SOP for running that specific protocol is outlined. It’s a good idea to review these SOPs on-line before you order. In this way you can be sure that you have the right equipment and know how to perform the procedures as outlined. An illustrated explanation of different types of immunoassay kits can be found under training and resources article “Introduction to Immunoassays.”

 

​It is always best to use the same lot of kits and saliva collection supplies when feasible. Salimetrics monitors kit and collection supply lot variation and does not approve lots that are not within specifications.

 

​Although salivary alph-amylase (sAA) can be sometimes be detected at birth the linkage between the ANS and salivary gland is not mature; thus sAA may not reflect the activity of the ANS in newborns. Salivary alpha-amylase can be detected in the saliva of infants as young as 3 months old. Over the first several months the amount of sAA produced in infants increases until it reaches the levels seen in adults at during the toddler period:

Davis, E. P., Granger, D. A.;Developmental differences in infant salivary alpha-amylase and cortisol responses to stress; Psychoneuroendocrinology (In press, 2009) (DOI:10.1016/j.psyneuen.2009.02.001)

There is also a Salimetrics document that provides this reference at LINK!

 

​Yes, read this Technical Bulletin that gives more information about running alpha amylase assays.

 

​Yes, Salimetrics recommends using a microtiter plate incubator/shaker, but other amylase substrate heating options are available - you can use an incubator that heats with air or a water bath.NOTE: It takes a long time to heat the substrate with either of these options; an hour or more – be sure to cover the substrate if you use an open air incubator to prevent evaporation of the substrate.

You can use the plate shaker in the plate reader to shake the plates.  I would caution you that some plate shakers shake to vigorously and liquid may spill into your plate reader. Most of the newer models of plate readers have several settings to adjust the speed of shaking. You should test the shaking with the appropriate volume of water in the wells to see if spilling does occur in order to avoid problems.

 

​This is a study design question. There are times when singlet testing is more acceptable, but generally duplicate testing is the ‘gold’ standard. Ideally, duplicate vs singlet testing should be performed to demonstrate no significant difference between the two. This could be also be shown by testing some samples in duplicate and some in singlet. Please make an appointment to talk with one of our experts by phone at 800.790.2258 or 760.448.5397

 

​Salimetrics kits have been validated at Salimetrics during development. You should contact your laboratory accrediting body to see if further validation is necessary in your laboratory.

​Salimetrics does not replace expired kit components. These kits are QC’d with the components that come with the kit and most the components are kit specific. Generally we do not have replacement components available because they are kit lot/batch specific and they have also expired. The best option if you kit has passed it’s expiration date is to purchase a new kit.  

 

​Analytical sensitivity or minimum detection limit of an assay, calculated from the mean plus two standard deviations of multiple replicate measurements of the zero calibrator within an assay run (intra-assay), defines the lowest concentration of an analyte that can be distinguished from zero (also called Limit of Detection, LOD or the Lower Limit of Sensitivity, LLS). 

In contrast, the functional sensitivity limit, represented as the lowest analyte concentration with an inter-assay coefficient of variation of 20%, provides a better indication of an assay’s actual performance (accuracy) when measuring samples with low concentrations of the analyte.