Low sodium-potassium ratio (na:k ratio) after Levothyroxine in dogs

27 reports to the FDA describe low sodium-potassium ratio (na:k ratio) in dogs given Levothyroxine. That is 0.9% of all reports for this medicine, compared with 0.1% across reports for all dog medicines, so it is reported unusually often with this medicine.

27Reports

59%Marked serious

0.0%Recovered

11%Died or euthanised

79 daysTypical onset

How soon it started

Same day

0 0.0%

1–2 days

0 0.0%

3–7 days

0 0.0%

1–4 weeks

1 6.3%

Over a month

15 94%

How the animals did

Still unwell when reported

9 33%

Euthanised

3 11%

Not known

15 56%

Problems reported at the same time

22 81%

11 41%

11 41%

10 37%

9 33%

Hyponatremia

7 26%

Thrombocytosis

5 19%

Weight loss

5 19%

Age of the animals

Under 1 year

1–3 years

4–7 years

8–11 years

12+ years

About this medicine

Levothyroxine treats an underactive thyroid.

Questions owners ask

Can Levothyroxine cause low sodium-potassium ratio (na:k ratio) in dogs?: 27 reports link the two, but a report alone does not prove the medicine was the cause: other illnesses, other medicines or coincidence can be involved. Your vet can judge it for your animal.
How soon after a dose was it reported?: In half of the reports with dates, it started within 79 days of the first dose.
What should I do?: Don't give another dose until you've spoken to your vet, and keep the packaging so you can tell them the product and dose. Your vet can also report it to the FDA (or you can, through the manufacturer or FDA form 1932a).

Low sodium-potassium ratio (na:k ratio) with similar medicines

Low sodium-potassium ratio (na:k ratio) after Trilostane (Vetoryl) 844 reports · 7.1% of its reports
Low sodium-potassium ratio (na:k ratio) after Insulin 79 reports · 1.1% of its reports

All reported side effects of Levothyroxine in dogs · Medicines most reported with low sodium-potassium ratio (na:k ratio)