What Tests To Get

Quick Answer: A cat with suspected or confirmed CKD needs, at minimum, a blood chemistry panel (including SDMA), a complete blood count, a urinalysis, and a blood pressure check. Ultrasound is worth discussing at the time of diagnosis. How often these are repeated depends on how stable your cat is, ranging from every one to two weeks while a new problem is being brought under control to every three to six months once things have settled down.

Test results tell you and your vet what is actually going on inside your cat, which often does not match what you can see from the outside. A cat who seems perfectly fine at home may already have significant electrolyte or mineral imbalances, while a cat who looks quite unwell may have relatively mild bloodwork. Testing lets you catch and treat problems before they become severe, and it gives you a baseline against which to measure whether treatment is working.

It is worth remembering that the numbers are a tool, not the whole picture. A cat who is eating, playing, and gaining weight despite so-so bloodwork is often doing better than the labs alone would suggest, and the reverse is also true. Treat the cat in front of you, and use the tests to guide that, rather than chasing a perfect number for its own sake.

These are the tests almost every CKD cat should have at diagnosis, and at regular intervals afterward.

Blood Chemistry Panel

This is the single most useful test for CKD and is usually run alongside the complete blood count from the same blood draw. It measures kidney function through BUN (or urea) and creatinine, and ideally also SDMA, which can pick up kidney disease earlier than creatinine alone. The panel also checks electrolytes such as potassium and sodium, the mineral pair phosphorus and calcium, and other values including albumin, glucose, and cholesterol that can flag additional problems.

We cover how to interpret each of these values in detail in our companion post on understanding your cat’s bloodwork.

Complete Blood Count (CBC)

The CBC examines the actual cells in the blood. For a CKD cat, the main things it reveals are whether anemia is present, which is extremely common as CKD progresses, and whether there are signs of infection or inflammation via the white blood cell count. Anemia in CKD cats is covered in depth on our anemia page, since it is common enough to warrant its own detailed discussion of causes and treatment.

Urinalysis

A urine sample tells your vet several things a blood test cannot. Urine specific gravity (USG) shows whether the kidneys are able to concentrate urine properly, and a low USG can sometimes flag CKD before it shows up in blood work at all. Urinalysis also checks for protein in the urine (proteinuria), which is a factor in how fast CKD tends to progress, and it can reveal early signs of a urinary tract or kidney infection.

Blood Pressure

High blood pressure (hypertension) is common in CKD cats and can cause sudden blindness along with other damage if it goes unchecked. Unfortunately, not every vet checks this routinely, so it is worth asking for it specifically if it is not already part of your cat’s visit.

Not every cat needs every test on this list, but they are worth knowing about.

Ultrasound. This is not automatically performed on every CKD cat, but growing evidence suggests it is worth doing at initial diagnosis for most cats, since it can pick up kidney stones, infection, or structural changes that bloodwork alone would miss. It is quick, does not usually require sedation, and is especially worth asking for if a kidney infection, kidney stones, or an enlarged kidney is suspected.

Parathyroid hormone (PTH) and ionized calcium. These are more specialized tests that come into play if secondary hyperparathyroidism is suspected, or if your cat’s calcium levels are unusually high or low. Most general labs cannot run these, so they typically need to go to a specialist laboratory.

Thyroid testing (T4). Hyperthyroidism is common in older cats and can complicate the picture of kidney function, since it tends to mask true kidney values. If your cat is showing signs of both conditions, or has unexplained weight loss, T4 testing helps sort out what is actually happening.

Pancreatitis testing. Cats with a low creatinine level that seems out of step with how ill they otherwise appear are sometimes dealing with pancreatitis rather than, or in addition to, CKD. A specific pancreatic test can help clarify this.

There is no single right answer here since it depends heavily on how stable your cat is, but the following is a reasonable starting framework.

In the first one to eight weeks after diagnosis or after starting a new treatment, more frequent monitoring is usually needed, sometimes as often as every one to two weeks, particularly if you are working to bring phosphorus, anemia, blood pressure, or an electrolyte imbalance under control. If your cat has recently started an ACE inhibitor or ARB medication, creatinine should typically be rechecked after seven to ten days.

Once your cat is stable and in IRIS Stage 2 or above, testing every one to three months is a reasonable rhythm.

For stable cats in early stage CKD, testing every three to six months is often sufficient, though we would not recommend going any longer than six months between checks even for a cat who seems to be doing well.

Whatever schedule you land on, always go back to the vet sooner if your cat seems off, regardless of when the next scheduled test is due.

Blood draws and vet visits are stressful for a lot of cats, and that stress can itself skew some results (glucose and CK in particular tend to rise with stress). A few things can help.

Staying with your cat during the blood draw, rather than having them taken to a treatment area, often helps a nervous cat stay calmer, though a small number of cats actually do better away from their owner. If your cat tends to fight blood draws, ask whether blood can be taken from a hind leg rather than the neck, which some cats tolerate much better even though it takes a little longer. It also helps to skip cleaning the fur with alcohol beforehand unless there is a specific medical reason to do so, since cats dislike the smell and it adds unnecessary stress without much benefit for a routine draw.

Ask for copies of every test result, even if your vet’s practice does not offer them automatically. They will look like a wall of numbers and abbreviations at first, but keeping your own records lets you track trends over time rather than looking at each result in isolation, and it means you have a full history on hand if you ever need to see a specialist or visit an emergency vet.

See: How to Create a Spreadsheet

Do I really need all of these tests, or can I start with just the basics? A chemistry panel and urinalysis will get you a diagnosis and cover the essentials. The other tests add useful detail, particularly SDMA and blood pressure, but discuss with your vet what fits your budget and your cat’s specific situation.

My vet only wants to see my cat every six months. Is that enough? For a stable cat in early stage CKD, six months is generally considered the outer limit rather than the ideal. If your cat is in a more advanced stage, or if anything is currently being adjusted, more frequent checks are usually worthwhile.

Can stress at the vet ruin my cat’s results? It can affect some values, particularly glucose, but it is not usually enough to throw off the core kidney values like creatinine or SDMA. If a result looks surprising, it is always reasonable to ask your vet whether stress could be a factor and whether a recheck makes sense.

Is it worth paying for tests my vet doesn’t automatically recommend, like SDMA or ultrasound? Both can add real value, SDMA for earlier detection and monitoring, and ultrasound for ruling out structural problems like stones. Whether they are worth the added cost depends on your cat’s situation and your own priorities, and it is a fair thing to discuss openly with your vet.

• IRIS treatment recommendations for CKD in cats (2023) International Renal Interest Society
• ISFM consensus guidelines on the diagnosis and management of feline chronic kidney disease (2016) Sparkes AH, Caney S, Chalhoub S, Elliott J, Finch N, Gajanayake I, Langston C, Lefebvre H, White J & Quimby J Journal of Feline Medicine & Surgery 18 pp219-239
• Using urine specific gravity (2024) Watson ADJ, Lefebvre HP & Elliott J International Renal Interest Society
• Pilot study to evaluate the potential use of the renal resistive index as a preliminary diagnostic tool for chronic kidney disease in cats (2018) Matos I, Azevedo P & Carreira LM Journal of Feline Medicine and Surgery 20(10) pp940-947
• Renal pelvic and ureteral ultrasonographic characteristics of cats with chronic kidney disease in comparison with normal cats, and cats with pyelonephritis or ureteral obstruction (2017) Quimby JM, Dowers K, Herndon AK, Randall EK Journal of Feline Medicine and Surgery 19(8) pp784-790