A life in the day

1/11/2005

Diabetes-Hypothyroidism Link

Filed under: — site admin @ 12:50 pm

Go away. You probably don’t want to bother reading this.

Still here, huh? Well, I just had a doctor’s visit, and I want to record what he told me before I forget it. If you care about the link between diabetes and hypothyroidism, go ahead and read on.

Dr. Lampugnale’s office referred me to an edocrinologist, Dr. Abourizk, who directs St Francis Hospital’s Diabetes Care Center. I was referred because after I was diagnosed with diabetes in May, I was diagnosed as hypothyroid in December; we want to find out if there is some underlying issue causing my endocrine glands to malfunction.

We don’t yet have answers to that question (I have some tests scheduled), but I did learn a bit about the potential link between these diseases. First of all, the type of hypothyroidism I have is what’s known as Hashimoto’s Thyroiditis, which means that my immune system is creating antibodies to thyroid peroxidase (TPO). These antibodies are attacking my thyroid gland, gradual causing its destruction. So it sounds as though, barring some medical breakthrough, I will be on thyroid medicine for the rest of my life. I didn’t ask about possibilities of this being reversed. I imagine that with my immune system causing the problem, the most we can do is counteract the effects.

Since my immune system is attacking one endocrine gland, there is an elevated risk that it might be attacking another one, namely my pancreas. Something called GAD (glutamic acid decarboxylase, thanks Google) antibodies can attack the islet cells of the pancreas, decreasing production of insulin.

This would not match my diagnosis of Type 2 diabetes, which is a problem in the use of insulin, not in its production. But it’s possible that I’m going through a slow onset of Type 1 diabetes, in which case I will at some point become dependent upon insulin. We’ll know more after two tests I’ll have at the end of the month, one testing for GAD antibodies and another scanning the pancreas itself for unusual growth.

I learned several other things in this visit: Hashimoto’s disease is significantly more common among women than men, and has a strong genetic component. If the immune system is attacking these endocrine glands, the adrenal glands are often in for some rough treatment as well. (The first symptom would be loss of appetite; no problem there.) Finally, I learned some about the relationship between the pituitary gland and the thyroid gland. The pituitary releases thyrotropin, a thyroid-stimulating hormone, also known as TSH. TSH induces the thyroid to create the hormone thyroxine (T4) as well as others. This T4 then inhibits the pituitary’s release of TSH, in a negative feedback loop. The most sensitive check for thyroid functioning is the check for TSH, since a drop of 50% in T4 corresponds to an 800% increase in TSH. The normal TSH range is 0.5 - 4 mIU/L. My reading was 9.75 mIU/L. I don’t have a sense of how bad that is, except that I’m now on the lowest dose of synthetic thyroid hormone generally prescribed. (And that mathematically, if the top of the normal range is eight times the bottom, having a level 2.5 times that of the top of the range might not be that bad.)

It sounds as though hypothyroidism won’t complicate the treatment of my diabetes, but it is likely to make certain of its symptoms worse. It’s going to be harder to lower my blood pressure, although today’s 105/88 reading is encouraging. It may also make it more difficult to lose weight. After losing 45 pounds in six months, I put eight back on in short order. Now I’ve taken three of those back off, but it’s very slow going. And hypothyroidsm may create cholesterol problems, although my cholesterol has been very good. Dr. Abourizk discussed putting me on statins. He’s very gung-ho on statins, and an article about the uses of statins, originaly published in the Hartford Courant with quotes from and a picture of Dr. Abourizk, is prominently displayed in his office. I will have to do more research first.

Still, I really am feeling old! I’m going to need one of those weekly pillboxes. :-(

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