Hyperthyroidism is a hormonal imbalance that leads to weight loss, a ravenous appetite, increased activity level and behavior changes. If left untreated, hyperthyroidism can lead to heart and kidney disease.
Information on hyperthyroidism from the Veterinary Information Network (VIN)
Interaction of Hyperthyroidism and Kidney Disease:
Hyperthyroid disease increases the metabolic rate and the blood pressure. Both of these processes are damaging to the kidneys. Therefore, to protect the kidneys, addressing any possible underlying hyperthyroid disease is even more important. One thing to note is that hyperthyroidism will increase the blood pressure and in so doing force the kidneys to work harder, this makes the kidneys appear as though they are doing a better job clearing toxins than they are capable of doing when the blood pressure is normal. This means that if your cat does have hyperthyroid disease, and he is treated, his recheck blood work may demonstrate much higher levels of BUN (blood urea nitrogen) and Cr (creatinine) and a lower concentration of waste in the urine (USPG). Yet even though the kidneys may appear "worse" after treatment for hyperthyroidism, as long as your cat has reasonable function remaining, your cat's kidney function will last longer as the damaging effects of hyperthyroidism have been removed. We have a page with more information about kidney disease in cats.
Hyperthyroidism tends to increase the metabolic rate, and frequently causes the heart to beat harder and faster than normal. This often leads to hypertrophic cardiomyopathy, where the walls of the heart become too thick and the chambers of the heart too small and noncompliant. This results in decreased efficiency of the pumping of the heart. If the condition is severe, stress or sudden exertion can cause animals to suddenly decompensate and develop life threatening abnormal heart contractions and rhythm.
Treating Hyperthyroidism:
We recommend treating hyperthyroidism. The most preferable method is with an injection of radiolabelled iodine. This is usually a one-time treatment and it usually controls the physiologic problems, especially cardiac problems, very well.
An alternative method is to treat with methimazole, a drug which eats away thyroid tissue. Methimazole is usually a life-long medication. The most common side effect is vomiting. Methimazole does not control the physiologic symptoms of hyperthyroidism as well as the radio-iodine treatment, but it is certainly preferable to no treatment.
Processing ....
Interaction of Hyperthyroidism and Kidney Disease:
