What is SDMA?
Symmetric dimethylarginine (SDMA) is an amino acid that is produced via breakdown of proteins by most cells in the body at a constant rate. It is primarily removed from the body by the kidneys and hence it can be used as a measurement of kidney function.
Other than SDMA, the other two common parameters of kidney function in the regular blood testing profiles are “BUN/Urea”, which stands for blood urea nitrogen, and “Crea”, which stands for creatinine. Both urea and creatinine are waste products produced primarily by the breakdown of ammonia from liver after digestion of proteins, and breakdown of muscle cells respectively. Both are primarily removed from the body by the kidneys via filtration.
When the kidneys have lost about 70% of their filtration ability, we will start to see an increase in their concentration in the blood, eventually going above normal levels.
Benefits of using SDMA
SDMA is more sensitive than “Crea” and “BUN” at detecting kidney disease, as the levels of blood serum SDMA will start to increase by the time kidneys have lost about 40% of their filtration ability.
SDMA is less affected by other factors such as our pets’ diet and sizes, concurrent illnesses, or kidney reabsorption, unlike urea and creatinine. A blood test following high protein diet or exercise can lead to a temporary increase of urea, but SDMA will remain unaffected. In very skinny patients or patients with advanced kidney failure that have lost most muscles bulk may reflect “low to normal” range creatinine level in their blood test, since creatinine is a byproduct of muscles.
SDMA testing enable us to identify patients with early kidney disease, prior to onset of clinical symptoms. This allows us to intervene, monitor and slow down the progression of kidney disease.
SDMA and other kidney markers
When SDMA value is increased, we also look at blood creatinine and urea levels to assess if this is an early or an ongoing kidney dysfunction. Urine testing is also used in conjunction with these blood tests to confirm kidney dysfunction and gauge its severity. Further down the line, there may be other factors to consider such as blood pressure and electrolytes.
These different markers, when used together, enable us to identify, stage and treat kidney patients accordingly. This allow our patients to enjoy more quality time with their beloved family.
For further information, you may refer to the following websites to understand more about kidney disease.
- Idexx SDMA testing: https://www.idexx.com/en/veterinary/reference-laboratories/sdma/why-sdma-matters/
- International Renal Interest Society (IRIS): http://www.iris-kidney.com/education/what_pet_owners_should_know_ckd.html