Question

Blood Test Results for Thyroxine and TSH: Part A

Use the following information to answer the next three questions.

	Vincent	Normal Range
Thyroxine Levels (ug/dl)	18	4.6-12
TSH Levels (mcU/mL)	0.006	0.4-4.2

1) What does he suffer from? I put graves, is that correct out of the following option " Graves, Crentinsm, Acromegaly or Increase levels of iodine"

2) Blood Test Results for Thyroxine and TSH: Part B

What does the feedback loop for Vincent look like?

*Be sure to include all the hormones and glands involved in the feedback loop.

*Indicate whether the hormone levels are increasing or decreasing.

*Use arrows to indicate the direction of influence and label whether it is negative or positive feedback.

3)

Blood Test Results for Thyroxine and TSH: Part D

To treat Vincent's conditions, the doctors removed a small part of the thyroid gland. After the surgery, what would the thyroxine feedback loop look like?

Use the feedback loop generated for the previous question and modify it to demonstrate the changes stemming from the medical treatment. (1 mark)

Answer 1

1. The person is suffering from Graves disease or hyperthyroidism. It is a condition where thyroxine hormone is produced much more than required. The levels of TSH are much lower than normal. It is due to excess thyroxine. TSH is produced only when levels of Thyroxine are low. In this csae levels of thyroxine are high, that is why TSH is much lower.

Graves disease is right.

2.

A tumour in thyroid gland is producing lot of thyroxine. That is why levels of thyroxine increased. Because levels of thyroxine are more TSH is very low.

3.

Here removal of part of thyroid is reducing the thyroxine hormonal levels. This reduced levels will give positive effect on hypothalamus and anterior pituitary as shown below. Pituitary is producing more TSH and thyroid gland gets stimulated to form more thyroxine.