Total T4 (Feline)

Also known as:ThyroxineTT4

Reference Range

Critical Low

<0.5

ug/dL

Reference Range

1-3

ug/dL

Optimal Range

1.2-2.5

ug/dL

Critical High

ug/dL

Also reported in: nmol/L

Thyroxine (T4) regulates metabolism. Normal levels mean your cat's thyroid is stable.

Low

Hypothyroidism is rare in cats unless they have been over-treated for hyperthyroidism.

What to do:

Discuss with your vet, especially if your cat is on methimazole.

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Normal

Thyroxine (T4) regulates metabolism. Normal levels mean your cat's thyroid is stable.

What to do:

No action needed.

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High

Hyperthyroidism is very common in older cats. It causes rapid weight loss, voracious appetite, and hyperactivity.

What to do:

Your vet will discuss treatment options: daily medication (methimazole), radioactive iodine therapy (I-131), or surgery.

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