Felis ISSN 2398-2950

SDMA

Synonym(s): Symmetric dimethylarginine

Contributor(s): Dominique Paepe, Yvonne McGrotty

Overview

  • SDMA is a byproduct of protein methylation that is released into circulation after proteolysis and excreted primarily (≥ 90%) by renal clearance.
  • SDMA correlates well with glomerular filtration rate (GFR) Glomerular filtration rate, remains stable under storage conditions used in practice and is nowadays available in many countries.
  • SDMA is a promising indirect marker of GFR. It appears to be a more sensitive biomarker for assessing kidney dysfunction than serum creatinine, which facilitates the diagnosis of early kidney dysfunction. In pets developing chronic kidney disease (CKD) Chronic kidney disease, SDMA exceeded the reference interval earlier than serum creatinine in the majority of animals, on average 9.8 months earlier in dogs and 17 months earlier in cats.
  • SDMA is not influenced by muscle mass which is a major advantage over serum creatinine. In cats or dogs (with or without CKD) that present with obvious muscle wasting, SDMA might give a more accurate estimate of kidney dysfunction than serum creatinine.
  • All causes of decreased GFR - namely pre-renal, renal (acute, chronic) and post-renal – will result in increased SDMA concentrations. Persistently increased SDMA in stable, well hydrated, non-azotemic cats or dogs indicates decreased kidney function and these pets can be diagnosed with CKD, IRIS stage 1.
  • SDMA has been provisionally added to the IRIS guidelines for staging and management of CKD in dogs and cats.

Sampling

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Tests

Methodologies

  • In the initial small animal studies, SDMA was measured using liquid chromatography-mass spectroscopy (LC-MS), which is a very accurate but costly and time-consuming assay. To overcome these limitatons, IDEXX laboratories have developed and validated a commercial immunoassay, namely IDEXX SDMATM. If commercial laboratories offer other SDMA assays it is important to verify whether these were adequately validated.

Availability

  • SDMA can be easily determined in many countries.

Validity

Sensitivity

  • A study in cats revealed a sensitivity of 100% for SDMA versus a sensitivity of only 17% for serum creatinine to detect a 30% decrease in GFR. Comparable data in dogs is not available.

Specificity

  • A study in cats revealed a specificity of 91% for SDMA versus a specificity of 100% for serum creatinine to detect a 30% decrease in GFR. Comparable data in dogs is not available.
  • In people, SDMA is not affected by non-renal diseases such as liver disease, cardiovascular disease, inflammatory disease and endocrine disease. Published scientific data on specificity of SDMA in cats or dogs is limited. 

Result Data

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Further Reading

Publications

Refereed Papers

  • Recent references from PubMed and VetMedResource.
  • Relford R, Robertson J &  Clements C (2016) Symmetric Dimethylarginine. Improving the diagnosis and staging of chronic kidney disease in small animals. Veterinary Clinics: Small Animal Practice. 46 (6), pp 941-960 PubMed.
  • Braff J, Obare E, Yerramilli M, Elliott J, Yerramilli M (2014) Relationship between serum symmetric dimethylarginine concentration and glomerular filtration rate in cats. Journal of Veterinary Internal Medicine 28 (6), pp 1699-1701 PubMed.
  • Hall J A, Yerramilli M, Obare E, Yerramilli M & Jewell  DE (2014) Comparison of serum concentrations of symmetric dimethylarginine and creatinine as kidney function biomarkers in cats with chronic kidney disease. Journal of Veterinary Internal Medicine 28 (6), pp 1676-1683 PubMed.
  • Hall J A, Yerramilli M, Obare E, Yerramilli M, Yu S & Jewell D E (2014) Comparison of serum concentrations of symmetric dimethylarginine and creatinine as kidney function biomarkers in healthy geriatric cats fed reduced protein foods enriched with fish oil, L-carnitine and medium-chain triglycerides. The Veterinary Journal 202 (3), pp 588-596 PubMed.

Other sources of information

  • International Renal Interest Society (IRIS). IRIS staging of CKD (2015) [online] Available at: iris-kidney.com [Last accessed 24 November 2016].
  • Frequently asked questions about SDMA. IDEXX laboratories [online] Available at: idexx.com [Last accessed 24 November 2016].


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