A Case Study on the Endocrine System 3

Part III – Thyroid Trouble


Once again, Ellie sat in the exam room waiting on Dr. Simmons. He
flew in the door, grabbed a stool and, to Ellie’s relief, got right to
the point. “Well, your blood work does show some problems with your
thyroid. Your TSH levels are lower than they should be, your T₄
levels are a bit high and your T₃ levels are very high.
Those results suggest that you might have Graves’ disease, which means
that your thyroid is releasing too much thyroid hormone. Since thyroid
hormones are responsible for your metabolic rate, that explains why your
heart rate and blood pressure are elevated, why you’ve felt nervous and
can’t sleep, and why you’ve lost weight even though you aren’t
dieting.”

Ellie’s mind whirled. “Sooooo, could this also be why I can’t
concentrate when I try to study and why I can’t seem to remember
anything?” Maybe there was still some hope for her in Dr. Kern’s
physiology class.

“Well, maybe,” Dr. Simmons answered. “Some studies suggest that
excess thyroid hormone is correlated with decreased attention,
concentration, and working memory. In other words, your thinking might
not be as clear as it should be. However, other experts argue that it’s
the anxiety and nervousness that cause patients to feel their thinking
is impaired, even though there is no actual impairment. The good news is
that with treatment patients report an improvement in their cognitive
abilities, regardless of the underlying cause.”

Ellie felt a twinge of relief. “Oh, good! That will certainly help my
grades. But why is my thyroid releasing too much hormone? And you said
my TSH levels were low. Isn’t TSH a thyroid hormone? If my thyroid is
too active, shouldn’t it be high instead of low?”

Ellie has just asked some very good questions. If you were Dr.
Simmons, how would you answer her?

Questions

1. What is causing Ellie’s thyroid to secrete too much hormone?
   
2. Is Ellie correct in thinking that TSH is a thyroid hormone? Why
   is her TSH level low instead of high?