SDMA in cats and dogs
SDMA (symmetric dimethylarginine) is a small molecule that the body makes at a steady rate and the kidneys clear from the blood. Vets read it next to creatinine to judge how well the kidneys filter. It often rises earlier than creatinine and depends much less on how much muscle the animal has.
What it shows
Every cell with a nucleus releases SDMA as part of normal protein turnover, and almost all of it leaves the body through the kidneys. When filtration slows, SDMA stays in the blood longer and its concentration rises. Studies in dogs and cats show that SDMA follows the glomerular filtration rate (GFR — how fast the kidneys filter blood) closely.
Its main advantage is independence from muscle. Creatinine comes from muscle, so a thin older cat can have a creatinine that looks reassuring while the kidneys are already weaker. SDMA is much less affected by muscle loss. IDEXX, which developed the veterinary test, reports that SDMA rises at about 40% loss of kidney function, earlier than creatinine; independent reviews find the two about equally sensitive, with a high SDMA less specific — so they work best together.
Higher than reference — what it may be a sign of
- Chronic kidney disease (CKD): a persistent rise above the lab’s range, with dehydration excluded, makes kidney disease probable even when creatinine is still inside its range.
- Acute kidney injury: toxins, kidney infection (pyelonephritis) and other sudden damage raise SDMA together with creatinine.
- Less blood reaching the kidneys: dehydration lowers filtration and can raise SDMA for a while; a vet rechecks once the animal is rehydrated.
- Other conditions: IDEXX lists high blood pressure and urinary tract infection among the causes to check. IRIS notes that SDMA may be raised in dogs with hypoadrenocorticism (Addison’s disease, a lack of adrenal hormones) and in hyperthyroid cats.
- Reasons outside kidney disease: some healthy greyhounds have values up to about 20 µg/dL, and fast-growing puppies can sit slightly above the adult range.
What it means for your pet is for the vet to decide.
Lower than reference
A low SDMA is rarely a concern on its own. The best-known situation is a cat with an overactive thyroid: the kidneys filter faster than usual, and eClinPath reports SDMA below 10 µg/dL in many such cats. Hyperthyroidism can hide kidney disease, so after the thyroid is under control a vet usually looks at SDMA and creatinine again. IRIS also warns that hemolysis in the sample can make SDMA falsely low.
Look at together with
- Creatinine — the classic kidney marker. SDMA above the range with creatinine still inside it is a typical early picture.
- Complete urinalysis and urine specific gravity — IDEXX recommends a full urinalysis whenever SDMA is above the range.
- UPC — protein loss in urine, a separate and important finding in kidney disease.
- Urea, phosphorus and blood pressure — the usual companions when kidney values are followed over time.
Units and conversion
Most labs report SDMA in µg/dL. Some use the SI unit µmol/L: 1 µmol/L equals about 20.2 µg/dL, so 0.7 µmol/L is roughly 14 µg/dL. In the app each row keeps the unit printed on the form, and the chart converts everything to one unit so results from different labs line up.
Reference range and IRIS stages
The reference range is on your lab’s form. IRIS and many labs use 14 µg/dL as the upper limit of the reference range for both dogs and cats; for puppies IDEXX gives a slightly higher limit of 16 µg/dL. One result above the range is a reason to repeat the test and look further, not a diagnosis — what matters is whether the rise persists, and the trend over several tests says more than one number.
After CKD is diagnosed, vets stage it with thresholds set by the International Renal Interest Society (IRIS) — in a stable, hydrated animal, using SDMA next to creatinine (IRIS staging guidelines, 2026). These are staging thresholds, not reference ranges:
| Stage | Dogs (µg/dL) | Cats (µg/dL) |
|---|---|---|
| 1 | < 18 | < 18 |
| 2 | 18–35 | 18–25 |
| 3 | 36–54 | 26–38 |
| 4 | > 54 | > 38 |
Source: iris-kidney.com
Cats and dogs
Cats are where SDMA helps most. CKD is common in older cats, and age brings muscle loss that pulls creatinine down; SDMA is far less affected by that, so it can show reduced filtration while creatinine still looks fine. Many cats with hyperthyroidism also have kidney disease, so in an older cat SDMA is read together with thyroid results. IDEXX uses the adult range for kittens as well.
In dogs SDMA is read the same way, with a few caveats. Sighthounds such as greyhounds can have SDMA above the usual limit with healthy kidneys. Fast-growing puppies may sit slightly above the adult range. IRIS lists hypoadrenocorticism (Addison’s disease) among conditions that can raise SDMA in dogs.
Add a lab form — Pet Tracker Space recognises the lines, keeps the form’s units and draws each indicator over time with your lab’s reference band.
Sources
- eClinPath (Cornell University) — SDMA
- IDEXX — IDEXX SDMA Test
- IDEXX — Interpreting your SDMA results
- International Renal Interest Society — IRIS Staging System
- Van Vertloo L. Renal Dysfunction in Dogs and Cats. Merck Veterinary Manual
- International Renal Interest Society — IRIS Staging of CKD (2026), PDF
This page explains what a lab value means. It is not a diagnosis and not a substitute for your veterinarian — only they can interpret results for your pet.