Question

Amanda has been suffering from exophthalmos (bulging of the eyes) for a couple of months and after careful lab analysis, the doctor noticed the presence of circulating autoantibodies that can bind to TSH receptors on thyroid cells and overstimulate the thyroid glands.

1. Draw the detailed endocrine pathway (starting with the hypothalamus) leading to Amanda’s condition.

2. Would Amanda be hypothyroid or hyperthyroid?

3.Would Amanda develop a goiter?

4. What is the role of negative feedback in this situation? Compare this situation to a person with a pituitary tumor that is oversecreting TSH (show your work by drawing the endocrine pathway- starting with the hypothalamus, and indicate the role of native feedback loop(s) for both situations)

Answer 1

1) HYPOTHALAMO - PITUITARY - THYROID AXIS

2) Amanda would be HYPERTHYROID due to overproduction of T3 and T4 by thyroid gland , as a result of overstimulation of TSH receptors by Thyroid stimulating autoantibodies.

3) Excessive stimulation of TSH receptor by autoantibodies, leads to upregulation of cAMP and Protien kinase C pathway, which leads to increased thyroid cell proliferation .

This causes the thyroid gland hyperplasia and the accompanying goiter .

GOITER causes compressive effects like hoarseness of voice and dysphagia

4)

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