FrançaisWhat SDMA measures
All cells produce SDMA when they break down certain proteins. It is released into the blood at a fairly steady rate and filtered out by the kidneys. Its level therefore reflects the glomerular filtration rate (GFR), the volume of blood the kidneys clean per minute [1, 3].
Its main advantage over creatinine is that it does not depend on muscle mass [1, 3]. A thin senior cat or a dog that has lost muscle can have a reassuring creatinine while filtration is already reduced. Studies show SDMA can detect a drop in filtration of about 20%, earlier than creatinine [1].
The test most widely used, and the one the International Renal Interest Society (IRIS) refers to, is the IDEXX SDMA assay. Results are given in µg/dL [1, 2].
How to read the SDMA line on the report
A result just above the interval is the most common situation, and the one that raises the most questions.
- Abbreviation SDMA, sometimes written IDEXX SDMA. It sits in the kidney section of the chemistry panel.
- Result The concentration in this sample. Small changes can come from the test itself, as well as from the kidneys [5].
- Unit µg/dL. A value in µmol/L is about 20 times smaller (14 µg/dL ≈ 0.7 µmol/L).
- Laboratory interval 0–14 µg/dL for adult dogs and cats on the IDEXX test; 0–16 µg/dL in growing puppies [2].
- Flag H: above the interval. IDEXX describes 15–19 µg/dL as mildly increased [2].
SDMA reference values and what IRIS says
| SDMA (µg/dL) | How it is described | What usually follows |
|---|---|---|
| 0–14 | Within the interval for adult dogs and cats [1, 2]. | Kidney disease is unlikely if creatinine is also normal, unless values are rising over time [2]. |
| 15–19 | Mildly increased [2]. | A complete urinalysis and a repeat test to see whether the increase persists [2]. Persistent values of 15–17 match IRIS stage 1 [1]. |
| 20 and above | Kidney disease probable [2]. | Urinalysis and further assessment without delay [2]. Persistent values above 17 can place a pet in IRIS stage 2, even with normal creatinine [1]. |
Some breeds have their own ranges. IRIS reports a proposed interval of 6.3–19.8 µg/dL for Greyhounds and 3.4–19.2 µg/dL for Birman cats [1]. Kittens use the adult interval; growing puppies can show slightly higher values that normalise with age [2].
Why a high SDMA is confirmed before conclusions are drawn
IRIS considers that a persistently increased SDMA is consistent with chronic kidney disease, but stresses that a single value can be misleading, and that staging only applies once the situation is stable. It suggests reassessing after 2 to 4 weeks: a change of less than 20 to 25% indicates stable filtration [1].
Large datasets show why. In a study of more than 16,000 cats and 16,000 dogs, when SDMA first rose to 15 to 19 µg/dL, the increase persisted in 53% of cats and 42% of dogs. Above 25 µg/dL, creatinine rose in 93% of cats and 92% of dogs within 24 months [4]. An independent study in cats also found substantial variation between measurements and between in-clinic and laboratory analysers: a measured result of 14 µg/dL could represent a value anywhere from about 8 to 20 [5].
In practice, a mildly high SDMA usually leads to a urine test, a blood pressure check, a review of hydration and medicines, and a repeat measurement.
What can affect an SDMA result
- Hydration. Dehydration lowers filtration and can raise SDMA as well as creatinine and urea [1, 2].
- Haemolysis. Broken red cells in the sample can give a falsely low SDMA [1, 2].
- Other conditions. SDMA may be increased in cats with an overactive thyroid and in dogs with Addison’s disease (hypoadrenocorticism); it is not affected by heart disease [1].
- Breed and age. See the specific ranges above [1, 2].
- Analyser. In-clinic and reference laboratory results are not interchangeable [5]: follow the trend on the same test.
Reading SDMA with creatinine (unit converter)
SDMA and creatinine are read together. When they disagree, which happens in about 9% of dogs and 17% of cats, IRIS suggests repeating both and interpreting them with muscle mass, age and other findings [1].
Creatinine is reported in mg/dL in the United States and in µmol/L in Europe. Use the converter below to put two reports in the same unit, then compare each with its own laboratory interval.
Unit converter
Equivalent values
- Creatinine, µmol/L–
- Creatinine, mg/L–
Conversion only changes the unit. Compare the result with the interval printed by the laboratory that measured it.
The values often read with SDMA
For an overview of kidney values in older pets, see our guide to senior pet blood work. Protein loss is detailed in protein in urine in dogs and cats.
Questions to ask your veterinarian
- Is my pet’s SDMA mildly or clearly increased, and how does it compare with previous results?
- Do the creatinine, urea and urinalysis results point in the same direction?
- Could dehydration or a medicine explain the result?
- When should we repeat the test, and on which analyser?
- If the increase persists, which IRIS stage would apply and what would change at home?
Get your pet’s whole report explained, value by value.
SDMA makes sense with creatinine, urea and the urinalysis. AI DiagAnimals reads the full report, respects each laboratory’s units and intervals and prepares the questions for your vet. The service opens soon: leave your email to be told first.
Frequently asked questions
What is SDMA in veterinary medicine?
A blood marker of kidney filtration. It is cleared almost entirely by the kidneys and rises when filtration falls, often before creatinine. It is used in dogs and cats and is part of the IRIS staging system [1, 3].
What is a normal SDMA for a dog or a cat?
On the IDEXX test, 0–14 µg/dL for adult dogs and cats, and up to 16 µg/dL in growing puppies [2]. Some breeds, such as Greyhounds and Birman cats, have wider ranges [1].
Can SDMA be affected by dehydration?
Yes. Dehydration reduces kidney filtration and can increase SDMA, creatinine and urea. This is one reason a high value is rechecked once the pet is well hydrated [1, 2].
Sources
- International Renal Interest Society (IRIS). IRIS Staging System. iris-kidney.com/iris-staging-system
- IDEXX Laboratories. Interpreting SDMA test results for cats and dogs. idexx.com/en/veterinary/reference-laboratories/sdma/interpreting-your-sdma-results
- Relford R, Robertson J, Clements C. Symmetric dimethylarginine: improving the diagnosis and staging of chronic kidney disease in small animals. Vet Clin North Am Small Anim Pract. 2016;46(6):941-960. Authors affiliated with IDEXX. doi.org/10.1016/j.cvsm.2016.06.010
- Mack RM et al. Longitudinal evaluation of symmetric dimethylarginine and concordance of kidney biomarkers in cats and dogs. Vet J. 2021;276:105732. IDEXX laboratory data. doi.org/10.1016/j.tvjl.2021.105732
- Baral RM, Freeman KP, Flatland B. Comparison of serum and plasma SDMA measured with point-of-care and reference laboratory analysers: implications for interpretation of SDMA in cats. J Feline Med Surg. 2021;23(10):906-920. doi.org/10.1177/1098612X20983260
Laboratory methods and reference intervals vary. This article explains; it does not diagnose. For a decision about your pet, use the original report and talk to your veterinarian. Our editorial policy.