“My Brother Calls Me ‘Bug Eyes’”: A Case Study on theEndocrine System

Nineteen-year-old Krista waited impatiently as Dr. Weismanscribbled in his chart. She hoped he was scribbling an explanationof what was wrong with her. She was tired of not feeling likeherself and tired of being so stressed about it. She wasparticularly tired of how her eyes seemed to bulge outward, so muchthat her 10-year-old brother had started calling her “BugEyes.”

Dr. Weisman finally put down his pen and looked at Krista.“Well, your blood pressure and pulse are elevated. You’ve lostweight without trying, you have difficulty sleeping, you perspiremore than usual and you’ve had continuing bouts of diarrhea. Thosethings, combined with the swelling in the front of your neck,suggest that you may be suffering from more than the stress ofcollege life. I think we need to run some blood tests to check yourthyroid function.”

Krista blinked in surprise. “All of those things can be causedby a problem with my thyroid? Even the way my eyes look?”

Dr. Weisman nodded. “Your thyroid secretes several hormones thathave widespread and varied effects. The protrusion of your eyes isa condition called exophthalmos – it is an inflammatory response toabnormal levels of thyroid hormones. The fact that you have thiscondition in addition to your other symptoms makes me fairlycertain this is a thyroid problem.”

Krista hoped Dr. Weisman was right. Having a medical explanationfor her symptoms would mean that she wasn’t losing her mind.Several days later, Krista met again with Dr. Weisman.

“Let’s talk about your test results,” he said. “Your thyroidhormone levels are elevated, but your level of thyroid-stimulatinghormone (TSH) is lower than it should be. Those results suggestthat you probably have Graves’ disease, which means that yourthyroid is overactive. But there’s good news too—this is acondition that we can treat relatively easily.”

Krista felt a twinge of relief at the doctor’s words, but aflurry of questions poured out of her mouth. “What made my thyroidgo crazy? And what is TSH? If it’s a thyroid hormone, why is it lowinstead of high like everything else? And what kind of treatment doI need? Will it fix my thyroid? Will I…”

Dr. Weisman laughed and held up his hand to stop the barrage ofquestions. “Hold on, Krista. I’ll explain everything, and with theright treatment, your brother may not be able to call you ‘BugEyes’ much longer.”

Post-StudyQuestions

1. Name the two hormones commonly referred to as “thyroidhormone” and describe their general actions.

1. Why would an overactive thyroid cause Krista’s weightloss, sweating, and elevated heart rate?

1. Krista wonders if TSH is a “thyroid hormone,” and Dr.Weisman explains that it is not. State the action ofthyroid-stimulating hormone (TSH) and name the gland that secretesit.

1. How is the secretion of TSH regulated under normalconditions?

1. In Graves’ disease, the immune system makes antibodiesthat stimulate TSH receptors on the thyroid gland. What effect doesthis have on Krista’s thyroid?

1. Why is Krista’s TSH level low instead ofhigh?