VetVaultCat blood test results explained: how to read a CBC and chemistry panel
Cat bloodwork usually has two parts: a complete blood count (CBC), which counts red cells, white cells and platelets, and a chemistry panel, which checks kidney, liver, protein, glucose, electrolyte and often thyroid values. Read each result against the reference range printed on your own report, and look for patterns rather than single flagged numbers.
How a cat lab report is laid out
Whether from an in-clinic analyzer or an outside lab, a cat blood report is usually a table with five columns:
- Test – often abbreviated, such as ALT.
- Result – your cat's number.
- Unit – conventional (mg/dL, common in the US) or SI (µmol/L); the same creatinine can read 2.0 or 177.
- Reference range – the range seen in healthy cats on that lab's equipment.
- Flag – H or L (or arrows) when a result is above or below the range.
| Test | Result | Unit | Reference range | Flag |
|---|---|---|---|---|
| Creatinine | 2.3 | mg/dL | 0.8–2.0 | H |
| ALT | 54 | U/L | 10–100 | |
| Glucose | 212 | mg/dL | 70–150 | H |
Notes on hemolysis (burst red cells) or lipemia (fat in the sample) can explain an odd result.
Always use the range on your own report. Ranges differ between laboratories and analyzers. The ranges in this guide are approximate values for typical adult cats, meant only to help you orient yourself.
Why one slightly out-of-range value is often not a problem
A reference range is normally built to include the middle 95% of healthy cats. By design, about 1 in 20 healthy cats falls just outside any single range, so on a panel of 20 to 30 tests a flag or two in a healthy cat is not unusual. Stress at the clinic, a recent meal, mild dehydration and sample handling can all shift values slightly.
Your vet weighs how far a value is out, whether related values agree, symptoms and earlier results. Some small changes do matter in cats, though: a mild ALP rise, a creatinine creeping upward over several tests while still inside the range, or a thyroid value in the upper part of normal in a senior cat that is losing weight. Trends often tell more than any single report.
Call your vet or an emergency clinic now – whatever recent bloodwork showed – if your cat:
- has not eaten for 24 hours or more;
- vomits repeatedly or cannot keep water down;
- breathes with effort or with the mouth open;
- collapses, is very weak or has a seizure;
- has yellow gums, skin or whites of the eyes (jaundice);
- is a male cat straining in the litter box and passing little or no urine. A urethral blockage is an emergency and can become life-threatening quickly.
CBC: red cells, white cells and platelets
The CBC describes the cells in the blood: red cells (anemia), white cells (inflammation, infection, stress) and platelets (clotting).
| Test and what it measures | Approx. range | Common reasons high | Common reasons low |
|---|---|---|---|
| RBC – red cell count | 5–10 million/µL | Dehydration; rarely overproduction of red cells | Anemia: blood loss (fleas, bleeding), red cell destruction (for example Mycoplasma haemofelis), reduced production (kidney disease, chronic inflammation, FeLV) |
| Hematocrit / PCV – share of blood made of red cells | 30–45% | ||
| Hemoglobin – oxygen-carrying protein | 9–15 g/dL | ||
| Reticulocytes – young red cells | Low unless anemic | In an anemic cat: the marrow is responding | In an anemic cat: poor marrow response (kidney disease, chronic illness, FeLV), or too soon after blood loss |
| WBC – total white cells | 5.5–19.5 ×103/µL | Inflammation, infection (abscesses), stress, excitement | Severe infection, viruses (FeLV, FIV, panleukopenia), marrow problems |
| Neutrophils – first-line infection fighters | 2.5–12.5 ×103/µL | Bacterial infection, inflammation, stress, steroids | Overwhelming infection, panleukopenia, FeLV/FIV, marrow suppression |
| Lymphocytes – immune cells | 1.5–7 ×103/µL | Fear during sampling (common in young cats), chronic inflammation, rarely lymphoma | Stress, illness, steroids |
| Eosinophils – allergy and parasite cells | 0–1.5 ×103/µL | Fleas, worms, allergic skin disease, feline asthma | Usually not significant |
| Platelets – clotting cell fragments | 300–800 ×103/µL | Inflammation, iron deficiency | Often falsely low because cat platelets clump in the tube; true lows from bleeding, clotting disorders, immune destruction or marrow disease |
Because platelet clumping is so common in cats, vets usually check a blood smear before treating a low count as real.
Chemistry panel, organ by organ
The chemistry panel measures substances dissolved in the blood, grouped here by organ.
| Test and what it measures | Approx. range | Common reasons high | Common reasons low |
|---|---|---|---|
| Kidney | |||
| Creatinine – muscle waste filtered by the kidneys | 0.8–2.0 mg/dL (about 70–180 µmol/L) | Dehydration, kidney disease, urinary blockage | Low muscle mass, which can hide kidney disease |
| BUN / urea – protein waste | 15–35 mg/dL (urea about 5–12.5 mmol/L) | Dehydration, kidney disease, blockage, high-protein meal, gut bleeding | Liver dysfunction, low-protein diet, heavy drinking and urinating |
| SDMA – kidney filtration marker | Under about 14 µg/dL | Reduced kidney filtration, often earlier than creatinine; dehydration | Not usually meaningful |
| Phosphorus – mineral cleared by the kidneys | 3–6.5 mg/dL (about 1–2.1 mmol/L); higher in kittens | Kidney disease, growing kittens, hemolyzed sample | Insulin treatment of diabetes, refeeding after starvation |
| Liver | |||
| ALT – enzyme inside liver cells | 10–100 U/L | Liver cell injury: fatty liver (hepatic lipidosis), inflammation, toxins, hyperthyroidism | Not usually meaningful |
| ALP – enzyme linked to bile flow and bone | 10–80 U/L | Hepatic lipidosis, bile duct disease, hyperthyroidism, diabetes, growing kittens | Not usually meaningful |
| GGT – bile duct enzyme | 0–5 U/L | Bile duct inflammation (cholangitis), blocked bile flow, pancreatitis | Not usually meaningful |
| Bilirubin – pigment from old red cells | Under about 0.4 mg/dL (about 7 µmol/L) | Red cell destruction, liver disease, bile duct blockage | Not usually meaningful |
| Protein | |||
| Total protein – albumin plus globulins | 6–8.5 g/dL | Dehydration, high globulins | Blood loss, protein loss through gut or kidneys, liver failure |
| Albumin – main protein made by the liver | 2.5–4 g/dL | Dehydration only | Gut or kidney protein loss, liver failure, inflammation, poor nutrition |
| Globulin – antibodies and inflammatory proteins | 2.5–5 g/dL | Chronic inflammation or infection (including dental disease), FIP, FIV, rarely some cancers | Blood loss, gut protein loss, young kittens |
| Glucose | |||
| Glucose – blood sugar at the moment of sampling | 70–150 mg/dL (about 3.9–8.3 mmol/L) | Stress, diabetes, steroid medication | Insulin overdose, severe infection, liver failure, kittens not eating, delayed sample processing |
| Fructosamine – average glucose over recent weeks | Lab-specific | Diabetes | Low blood proteins, hyperthyroidism |
| Electrolytes | |||
| Sodium – water balance | 145–158 mmol/L | Dehydration, not drinking enough | Vomiting, diarrhea, fluid build-up, diabetes complications |
| Potassium – nerve and muscle function | 3.5–5.5 mmol/L | Urethral blockage (emergency), acute kidney injury | Chronic kidney disease, poor appetite, vomiting |
| Chloride – moves with sodium and acid balance | 110–125 mmol/L | Dehydration, some acid–base disorders | Vomiting (loss of stomach acid) |
| Calcium (total) – bones, nerves, muscles | 8–11 mg/dL (about 2–2.75 mmol/L) | Idiopathic hypercalcemia, kidney disease, some cancers, vitamin D toxicity | Low albumin, kidney disease, urethral blockage, pancreatitis, after thyroid surgery |
| Thyroid | |||
| Total T4 – main thyroid hormone | 0.8–4.7 µg/dL (about 10–60 nmol/L) | Hyperthyroidism | Illness elsewhere in the body, hyperthyroid treatment, some medications |
| Pancreas | |||
| fPLI (Spec fPL) – pancreas-specific lipase | Lab cut-offs: normal, gray zone, consistent with pancreatitis | Pancreatitis | Not usually meaningful |
Kidney values
Creatinine, BUN, SDMA and phosphorus are read together and with urine concentration (urine specific gravity). Because creatinine depends on muscle mass, a thin senior cat can show a "normal" creatinine despite reduced kidney function. More in our guide to cat kidney values.
Liver values
Cats have little ALP in the liver, clear it from the blood quickly and, unlike dogs, do not make extra ALP in response to steroids. So even a mild ALP rise deserves attention in a cat. In hepatic lipidosis ALP often rises much more than GGT; when both rise, bile duct or pancreatic disease becomes more likely.
Protein values
A low albumin-to-globulin ratio is one of several clues vets consider when FIP is suspected, but it does not diagnose FIP on its own.
Glucose and fructosamine
Cats are known for stress hyperglycemia: a car ride and blood draw can push glucose to levels that look like diabetes. Fructosamine reflects average glucose over roughly the previous one to three weeks (in cats, mostly the last one to two) and is not raised by brief stress, so vets use it, with a urine sugar test, to tell the two apart.
Electrolytes
Low potassium is common in cats with chronic kidney disease and can cause muscle weakness. High potassium in a cat that cannot urinate points to a urethral blockage. Total calcium falls when albumin is low, so vets may measure ionized (free) calcium instead.
Thyroid (T4)
Hyperthyroidism commonly raises total T4 in older cats, and often ALT and ALP too. Early cases, or cats with another illness, may show a T4 in the upper part of normal, so vets may repeat the test or add free T4. See our cat thyroid T4 guide.
Pancreas
In cats, the amylase and lipase on many routine panels are poor at detecting pancreatitis. Vets rely on fPLI (Spec fPL, or the in-clinic SNAP fPL) together with symptoms and ultrasound.
Blood panels for senior cats
The AAHA/AAFP feline life-stage guidelines call cats aged 7–10 mature adults and cats over 10 seniors. Many vets recommend a baseline panel around age 7 and regular rechecks after that, often once or twice a year for seniors, because:
- cats hide illness, and changes often show in blood and urine before symptoms;
- a baseline taken while healthy lets later results be compared with your cat's own trend;
- several common senior conditions are treatable, and finding them early gives more options.
A typical senior screen includes a CBC, a chemistry panel (often with SDMA), total T4, a urinalysis and a blood pressure check. Common findings:
- Chronic kidney disease – rising creatinine and SDMA, dilute urine, sometimes low potassium or high phosphorus.
- Hyperthyroidism – high T4, often with raised liver enzymes and weight loss despite a good appetite.
- Diabetes mellitus – persistently high glucose, sugar in the urine and a raised fructosamine.
These conditions interact. Hyperthyroidism increases blood flow and filtration through the kidneys, which can lower creatinine and SDMA and hide kidney disease, so vets often recheck kidney values after thyroid treatment starts.
Questions to ask your vet about the results
- Which results are outside the range, and which of them matter for my cat?
- Could stress, a recent meal or the sample itself explain any flags?
- Do the abnormal values fit a pattern, and what are the possible causes?
- How do these results compare with my cat's previous tests?
- Do we need a urinalysis, blood pressure check or repeat test, and when?
- Is anything urgent? Which signs at home should make me call you?
- Can I have a copy of the full report with reference ranges?
Frequently asked questions
How do I read my cat's blood test results?
Compare each result with the reference range printed on the same report, in the same units. Values flagged H or L fall outside that range. Look at how related values fit together and discuss them with your vet rather than judging one number on its own.
Is one slightly abnormal value on a cat blood test a concern?
Often it is not. Reference ranges are built so that about 1 in 20 healthy cats falls outside each one, and stress, a recent meal or sample handling can shift results. Your vet weighs the size of the change, related values, symptoms and earlier results.
What does high ALT mean in a cat?
ALT is an enzyme released when liver cells are damaged. In cats it can rise with fatty liver (hepatic lipidosis), inflammation of the liver or bile ducts, toxins and hyperthyroidism. The size of the rise and the other liver values help your vet decide what to check next.
Does high glucose on a blood test mean my cat has diabetes?
Not necessarily. Many cats develop stress hyperglycemia at the clinic, which can push glucose well above the range. Vets usually look for persistently high glucose, sugar in the urine and a raised fructosamine before diagnosing diabetes.
Why are my cat's platelets low on the blood test?
Cat platelets clump together easily in the sample tube, and analyzers can miss the clumps, giving a falsely low count. Vets usually check a blood smear before deciding the count is truly low.
How often should a senior cat have blood work?
Many vets suggest a baseline panel in mature adulthood (around 7 years) and regular rechecks as cats age, often once or twice a year for seniors. Your vet will set the schedule based on your cat's health.
Sources
- eClinPath: A Resource for Veterinary Clinical Pathology, Cornell University College of Veterinary Medicine.
- IRIS Guidelines, International Renal Interest Society.
- 2021 AAHA/AAFP Feline Life Stage Guidelines.
- 2021 AAFP Senior Care Guidelines.
- Health concerns in cats, International Cat Care.
- Cornell Feline Health Center, Cornell University.