Hyperthyroidism and Your Diabetic Cat

Hyperthyroidism and Your Diabetic Cat

What is Hyperthroidism

Hyperthyroidism is a condition in which the thyroid gland produces more of its hormones than it should. It is most common in older cats. When this occurs, the cat's body runs much faster than it normally would. There are two hormones commonly related to hyperthyroidism. The first is thyroxin, known as T4, the second is triiodothyronine, known as T3.

The thyroid gland is located in the cat's neck, on either side of the throat. It regulates the body's basal metabolic rate by releasing these two hormones. The T3 hormone has a much faster reaction time, but lives in the bloodstream for a much shorter time, while T4 takes longer to take effect, but lasts longer in the blood. The thyroid only produces a fraction of the T3 that the body needs, the remainder is creatd by liver when it converts the T4 to T3.

Hyperthyroidism affects many organs in the body. The heart beats faster as a result of the increased hormone levels. Left untreated, this can lead to a serious situation called Hypertropic Cardiomyopathy. The kidneys receive an increase in blood flow as a result of the increase in heart rate. Because older cats are prone to both hyperthyroidism and kidney disease, treating the hyperthyroidism can actually cause the kidney function to worsen.

Symptoms

The symptoms of hyperthyroidism are varied. The most common symptoms include weight loss, increased appetite, a poor coat, increased drinking and increased urination. If you have a diabetic cat, those symptoms probably sound familiar. Other symptoms can include, agressive behavior, an increased heart rate, increased activity and vomiting. These symptoms indicate why you should always do a complete blood panel when your cat is diagnosed as diabetic.

Diagnosis

Hyperthyroidism can be diagnosed three primary ways. First, a blood test can detect increased T3 and T4 hormone levels in the blood stream. This is not always accurate, however. In some cases, a cat may have only elevated T4 levels, but normal or near normal T3 levels.

A veterinarian can also feel the enlarged thyroid glands on the cat's neck. Again, this is not always accurate, as the gland may enlarge enough that it actually sinks further into the neck. A cat with hyperthyroidism may have elevated hormone levels without swollen glands, and may have swollen glands with normal or near-normal hormone levels. This is another reason to run the full blood panel to identify or rule out other illnesses.

A nuclear medicine can can also detect overly active thyroid glands. This may be the most reliable test, but it is also the most expensive and is not available in all areas. It is also the most traumatic for the cat, who must stay at the medical for several days while the radioactive material clears the body.

There are other tests that can also be used, although they are less common. These include the T3 suppression test, the thyrotropin-releasing hormone stimulation test, and the measurement of free T4.

Impact on Diabetes

Because hyperthyroidism shares so many symptoms with feline diabetes, treating a diabetic cat with hyperthyroidism can be difficult. It is difficult to tell of treatment of one illness is effective based on the symptoms alone, because the symptoms of one illness may still be present. The important term here is difficult. Not "impossible".

Because hyperthyroidism affect metabolism, it can also affect insulin onset, duration and peak. This again makes the treatment of feline diabetes more difficult, and potentially dangerous, as slowing the metabolism could lead to hypoglycemia. It is generally best to treat the hyperthyroidism first, then treat the feline diabetes, if possible.

Treatment

There are three primary treatments of hyperthyroidism. The first is with a pill commonly known as Tapazole, generic name methimazole. This is given one to three times daily. This does not cure the illness, only treats the illness, so it must be given for life or until one of the other treatments is done. It may take up to several weeks for the methimazole to reduce the hormone levels to normal.

Surgery can be used to remove one or both thyroid glands. Usually, the cat will be placed on methimazole for a month or two prior to the surgical procedure. Only cats who are strong enough to undergo anesthesia can be considered for surgery. There is a risk of nerve damage as a result of the surgery and it is possible that the parathyroid glands can be damaged, which can cause low blood calcium levels, which can lead to seizures. But generally speaking, the surgery option is usually an effective treatment when performed by a qualified veterinarian. It is usually only ineffective with a condition known as ectopic thyroid, in which extra thyroid tissue is distributed in other locations within the body.

The third treatment option is radioactive iodine treatment. In this treatment, radioactive iodine is administered intravenously and accumulates in the abnormal thyroid cells, killing them but usually leaving the normal cells in tact. The biggest disadvantage to radioactive iodine treatment is that you must do to a specialized facility and your cat will need to remain until the radioactivity decreases, which typically takes one to three weeks. There is also a chance of this treatment causing hypothyroidism, although this is rare.

Conclusion

Hyperthyroidism can be easily managed or treated. When the vet tells you that your cat is diabetic, it is always best to run full blood tests to rule out other conditions such as hyperthyroidism. You should do this before you begin treatment for diabetes, if you can. Always consult your vet first.

Bibliography:

Hyperthyroidism in YOur Cat, Its Cause and Its Treatment

Hyperthyroidism in Cats

Hyperthroidism in cats

Feline Hyperthroidism