Understanding blood tests

A laboratory report is written for a veterinary surgeon, not for you. Each article explains one line of your results and prepares you for your consultation.

Cat

Cat losing weight but still eating: the three things a blood test separates

A cat over eight losing weight with a kept or bigger appetite: how T4, glucose, fructosamine, creatinine, SDMA and urea tell the three usual causes apart.

Dog

Dog blood test cost in the UK: what changes the figure on the invoice

Indicative UK ranges for taking a sample, a basic panel and an extended panel, what is included, why out of hours costs more, and how to ask for a written estimate.

Dog

Dog blood test results: how to read the report line by line

Biochemistry against haematology, why the printed reference range differs between laboratories, what a high or low flag means, and the order to read the lines in.

Dog

Dog drinking a lot of water and peeing: what the blood test looks for

Why a dog suddenly drinking and urinating more gets a blood and urine test, what the kidney, diabetes and Cushing's lines of enquiry show, and how to measure intake.

Dog

Dog vomiting but acting normal: what is urgent and what a blood test adds

Which signs alongside vomiting in a dog mean ring now, which wait for the next appointment, and what kidney, liver, pancreas and electrolyte lines contribute.

Dog

High alkaline phosphatase in dogs: plenty of ordinary causes

In dogs, ALP goes up for plenty of ordinary reasons, bone and corticosteroids included. How to read the line without over-reading what it actually says.

Dog

High ALT in dogs: liver damage, not liver failure

ALT tells you that liver cells have leaked their contents, not that the liver is working badly. That single difference changes how the whole panel reads.

Cat

High blood glucose in cats: stress before diabetes

In cats, the stress of a consultation pushes blood sugar up on its own within minutes. Fructosamine is the only parameter that settles the question properly.

Dog

High calcium in dogs: why a tumour is looked for first

What a raised calcium signals in a dog, why it always has to be confirmed with an ionised calcium, and the household vitamin D sources owners forget about.

Cat

High creatinine in cats: why it is never read on its own

Why a high creatinine in a cat is always read alongside the urine, the hydration state and the muscle mass, and never as a single line on a blood report.

Cat

High SDMA in cats: the marker that speaks before creatinine

SDMA moves earlier than creatinine and does not depend on muscle mass at all. What has to be read alongside it before anyone draws a conclusion from it.

Cat

High T4 in cats: hyperthyroidism and what it hides

Why a high T4 in an older cat is treated while the kidney is watched closely, and what tends to come to light once the thyroid has been settled back down.

Dog

High urea in dogs: the kidney is not always to blame

Urea rises for dietary, digestive and kidney reasons alike. How to read it alongside the creatinine and the urine rather than as a single line on its own.

Dog

Low haematocrit in dogs: the real question is the bone marrow

A low haematocrit opens one real question: is the bone marrow still responding? The reticulocyte count answers it, and the haematocrit itself never does.

Dog

Low platelets in dogs: the blood smear before anything else

Why a low platelet count has to be confirmed down a microscope before anyone investigates, and what the vet then looks for once the figure is validated.

Cat

Low potassium in cats: the vicious circle with the kidney

What a low potassium indicates in a cat, why the kidney is nearly always involved in it, and the clinical sign owners routinely mistake for plain old age.

Dog

Low urine specific gravity in dogs: what urine says about the kidney

Dilute urine can come from drinking, from a medicine or from the kidney itself. How to read this line alongside the creatinine on the same blood panel.

Cat

Renal values in cats: what each line on the report actually measures

Creatinine, SDMA, urea, urine specific gravity, phosphorus, UPC and potassium: what each renal value measures in a cat, why they move at different times.