Senior Cat Blood Test Results: Common Terms Explained in Plain English

Senior cat blood test results can feel confusing at first. A report may include abbreviations, numbers, arrows, and words like “high”, “low”, “borderline”, or “monitor”. If your cat is older, that can naturally make you worry.

This guide explains common blood test terms in plain English so you can feel more prepared when speaking to your vet. It is not designed to help you diagnose your cat from a report. Blood results only make sense when your vet looks at the full picture, including your cat’s age, symptoms, examination, weight, urine results, and previous tests.

Disclaimer: This article is for educational purposes only and is not a substitute for professional veterinary advice. If your cat is in pain, losing weight, vomiting frequently, or acting differently, speak to your vet.

Why vets often recommend blood tests for senior cats

Older cats are very good at hiding changes. A senior cat may still eat, sleep, groom, and move around fairly normally even when something subtle is changing inside the body.

Blood tests can help your vet look at broad areas of internal health, such as:

• Blood cells
• Kidney-related values
• Liver-related values
• Thyroid hormone
• Blood sugar
• Proteins
• Electrolytes

For many senior cats, blood tests are also useful because they create a baseline. This means your vet has a record of what is normal, borderline, or changing for your individual cat.

That is especially helpful over time. A single result can be useful, but a pattern across several tests may give your vet more context.

For more background on routine senior care, you may also find Senior cat check-ups: what “senior wellness” visits often include helpful.

Why one result rarely tells the whole story

It is easy to look at one flagged result and assume it explains everything. In reality, blood test results are more like clues than final answers.

A value may be slightly outside the expected range because of several possible factors, including:

• Hydration level
• Stress during the vet visit
• Recent eating
• Medication history
• Sample handling
• Lab reference ranges
• Other health findings

This is why your vet may not focus on one number alone. They may compare the result with your cat’s symptoms, physical examination, urine concentration, blood pressure, weight trend, and previous bloodwork.

For example, if a kidney-related value is raised, your vet may want to look at urine results too. If thyroid results are borderline, your vet may suggest repeating the test later or considering your cat’s symptoms before drawing conclusions.

The important point is this: a result being outside the range does not automatically tell you the full cause or seriousness.

Common sections on a senior cat blood test report

Blood reports vary by clinic and laboratory, but many include two broad areas:

Section	What it usually looks at	Plain-English purpose
CBC	Blood cells	Looks at red blood cells, white blood cells, and platelets
Chemistry panel	Organs, proteins, minerals, and other body markers	Helps your vet assess patterns linked with internal health
Thyroid test	T4 or related thyroid values	Often checked in older cats
Glucose	Blood sugar	Interpreted with symptoms, stress level, and sometimes urine results
Electrolytes	Minerals such as sodium, potassium, and chloride	Helps assess hydration and body balance

Some cats may also have urine testing, blood pressure checks, or other tests depending on their age, symptoms, and previous results.

Blood cell terms: CBC, red cells, white cells, and platelets

CBC

CBC usually means complete blood count. This part of the blood test looks at different types of blood cells.

It does not diagnose one condition by itself. Instead, it gives your vet a broad picture of what is happening in the blood.

Red blood cells

Red blood cells help carry oxygen around the body.

If red blood cell values are outside the expected range, your vet may look more closely at your cat’s energy levels, gum colour, appetite, breathing, and other blood values.

This does not mean you should try to interpret the red blood cell result alone. Your vet will consider whether the result fits your cat’s overall condition.

White blood cells

White blood cells are linked with the immune system.

Changes in white blood cells may lead your vet to consider inflammation, infection, stress, or other context. But again, this is not a one-result answer.

White blood cell results are usually interpreted alongside your cat’s symptoms, temperature, examination findings, and any other test results.

Platelets

Platelets help blood clot.

If platelet numbers look low or unusual, your vet may interpret this carefully. Sometimes platelet readings can be affected by how the sample behaves, so this is another area where context matters.

Kidney-related terms: creatinine, urea/BUN, SDMA, and phosphorus

Kidney-related results are commonly discussed in senior cats, but they need careful interpretation. Your vet will usually look at the pattern rather than one isolated value.

For more detail on early owner observations, see Senior cat kidney disease: early signs owners might notice.

Creatinine

Creatinine is a waste product that vets often consider when assessing kidney function.

It is usually interpreted with other information, such as:

• Hydration
• Urine concentration
• Body condition
• Weight changes
• Other kidney-related values
• Previous results

Creatinine is useful, but it is not a diagnosis by itself.

Urea or BUN

Urea, sometimes shown as BUN depending on the report, is another waste-product term your vet may discuss.

It can be linked with kidney assessment, but it can also be influenced by other factors. That is why your vet usually interprets it alongside creatinine, urine findings, hydration, and your cat’s general condition.

SDMA

SDMA is a kidney-related marker included on some blood panels.

Your vet may use it as part of a wider kidney assessment, especially when looking for patterns or changes over time. It still needs context and may be interpreted alongside urine testing, creatinine, body weight, and symptoms.

Phosphorus

Phosphorus is a mineral that may be discussed when vets are looking at kidney health or overall body balance.

It should not be interpreted alone, and owners should not change diet or add supplements based only on a phosphorus value. If your vet mentions phosphorus, ask how it fits with your cat’s other results and overall health.

Liver-related terms: ALT, ALP, and bilirubin

Liver-related values can appear on a chemistry panel. These results can look worrying on a report, but they still need the full veterinary picture.

ALT

ALT is a liver enzyme.

If ALT is outside the expected range, your vet may consider whether this area needs closer discussion or follow-up. However, ALT does not explain the full reason by itself.

Your vet may look at other liver values, your cat’s appetite, weight, vomiting history, medication use, and examination findings.

ALP

ALP is another enzyme that may appear on the report.

It is often interpreted with ALT, bilirubin, and your cat’s overall signs. Like other values, it is a clue rather than a complete answer.

Bilirubin

Bilirubin is a pigment-related value.

Your vet may consider it when looking at liver, bile, or red blood cell context. It is not something owners should try to interpret from the number alone.

If bilirubin is mentioned, ask your vet how it fits with the rest of your cat’s results.

Thyroid term: T4

T4 is a thyroid hormone value that is commonly checked in older cats.

Your vet may discuss thyroid testing if your senior cat has changes such as:

• Weight loss
• Increased appetite
• Drinking more
• Restlessness
• Behaviour changes
• Increased activity or agitation
• Vomiting or digestive changes

T4 results can sometimes be clear, but they can also be borderline or need follow-up depending on the cat. Your vet may compare the result with symptoms, weight trend, heart rate, and other test findings.

For more owner-friendly background, see Hyperthyroidism in Older Cats: Common Signs Owners May Notice

Glucose and blood sugar

Glucose means blood sugar.

A glucose result can be useful, but it needs context. Some cats become very stressed during vet visits, and stress can affect certain readings. Your vet may also compare glucose with urine results, symptoms, appetite, thirst, weight changes, or further testing.

Do not assume one glucose result tells the whole story. If your vet mentions glucose, ask whether it fits with your cat’s behaviour at home and whether any follow-up is needed.

Proteins and electrolytes

Total protein, albumin, and globulin

Protein values may include terms such as total protein, albumin, and globulin.

These can relate to several areas of health, including hydration, inflammation, liver function, kidney function, gut health, and immune context.

That does not mean one protein value points to one simple answer. Your vet will look at the pattern and decide whether it matters for your cat.

Sodium, potassium, and chloride

Sodium, potassium, and chloride are electrolytes.

Electrolytes help with normal body function. Your vet may interpret them alongside hydration, kidney values, appetite, vomiting, diarrhoea, and your cat’s general condition.

If an electrolyte result is mentioned, ask your vet whether it is mild, significant, or something they want to recheck.

What “high”, “low”, “borderline”, or “monitor” may mean

Blood test reports often flag values as high or low. That can look alarming, but it does not always mean something serious is happening.

Here is what these words usually mean in plain English:

Word on the report	What it may mean	What to ask your vet
High	Above that lab’s reference range	“Is this mild or significant for my cat?”
Low	Below that lab’s reference range	“Does this fit with my cat’s symptoms?”
Borderline	Close to the edge of the range	“Should we recheck this later?”
Monitor	Watch the value over time	“What changes should I look for at home?”
Stable	Similar to previous results	“Is this reassuring for my cat?”
Trending	Changing across tests	“Is the pattern more important than the single number?”

Reference ranges can vary between labs, and some cats have individual patterns that your vet will recognise over time.

The safest question is not “What does this number mean online?” but:

“What does this result mean for my cat, based on the full picture?”

Questions to ask your vet about senior cat blood test results

You do not need to understand every abbreviation before speaking to your vet. A few clear questions can make the conversation much easier.

You can also ask your vet to highlight the two or three results that matter most, rather than trying to understand the whole report at once.

Helpful questions include:

• Which results are most important for my cat right now?
• Are any values only mildly outside the expected range?
• Do these results match my cat’s symptoms or behaviour?
• How do these results compare with previous tests?
• Would urine testing, blood pressure, or repeat bloodwork help?
• Is there anything I should monitor at home?
• When should we recheck or follow up?
• Are there any changes that mean I should speak to you sooner?

It is also reasonable to ask your vet to explain one or two key values rather than the whole report at once. That can make the information easier to absorb.

Owner-friendly blood test discussion checklist

Before or after your appointment, it can help to write down what you have noticed at home.

Use this simple checklist:

• Recent weight changes
• Appetite changes
• Drinking more or less
• Litter tray changes
• Vomiting or diarrhoea
• Energy level
• Mobility changes
• Grooming changes
• Behaviour changes
• Medication or supplements your cat already takes
• Questions you want to ask about the results
• Follow-up date or recheck plan

This is not about diagnosing your cat yourself. It simply gives your vet better context.

What to keep at home after the appointment

If your vet provides a copy of the blood test report, keep it with your cat’s notes.

Useful things to keep together include:

• Blood test reports
• Urine test results, if provided
• Weight records
• Medication instructions from your vet
• Follow-up dates
• Notes from vet conversations
• Home observations about appetite, thirst, litter tray habits, and behaviour

This can make future appointments easier, especially if your cat has repeat tests over time.

When to speak to your vet sooner

Some changes should not wait for the next routine appointment.

Speak to your vet sooner if your senior cat:

• Stops eating
• Is losing weight quickly
• Vomits repeatedly
• Seems weak, collapsed, or unusually unsteady
• Has fast, laboured, or difficult breathing
• Seems in obvious pain
• Has difficulty urinating
• Has blood in the urine or stools
• Seems suddenly confused or very different in behaviour
• Has a result your vet specifically asked you to monitor

If you are unsure whether a change matters, it is safer to ask your vet than to wait and worry.

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FAQs

Final thoughts

Senior cat blood test results can look intimidating, especially when the report is full of abbreviations and flagged values. But you do not need to decode every number by yourself.

Your vet’s role is to interpret the full pattern. Your role is to ask clear questions, share what you have noticed at home, and follow the plan your vet recommends.

For a wider overview of older cat health, you may also find Senior Cat Health: A Practical Guide for Older Cats helpful.

External references

• Cornell Feline Health Center: The Special Needs of the Senior Cat
• AAHA: The ABCs of Cat Bloodwork: What Those Results Really Mean