Reference no: EM131652927

Use the following case study for the next 2 questions:

A 40 year old female has a four month history of nervousness, tremors, palpitations, sweating, and discomfort with heat. She has lost 25 lbs, despite a high rate of food intake. She also feels very weak and fatigues with moderate exercise that previously would not have tired her. She has missed three consecutive menstrual periods. Her pulse rate at rest is 100 beats/min. Following rapid stair climbing, her pulse increased to 150 beats/min within 20 seconds. Pulse pressure was 150/60 and respiratory rate was 20/min. Her skin is warm and moist, her speech rapid, and movements in general were hyperkinetic. Her facial expression is one of a fixed stare. She exhibits tremors, exaggerated reflexes, yet requires assistance to stand from a squatting position. The thyroid gland was diffusely enlarged. Total serum T4 concentrations were 26µg/dl (normal is 5.0 to 12), a free T4 concentration of 4.1 ng/dl (normal is 0.8 to 2.4), and a serum TSH concentration of 0.01 mIU/mL (normal is 0.5 to 5.0). A 24-hour uptake of radioactive iodine was 70% (normal is 8% to 30%). A pregnancy test was negative. The patient was treated with thiouracil (a thyroid peroxidase inhibitor) and four weeks later, her symptoms had improved with T4 declining to 11µg/dl. Interestingly, after 13 weeks of the same drug therapy, serum T4 decreased further to 3.6 µg/dl and she complained of the recurrence of fatigue, lethargy, and extreme intolerance to cold. Her body weight had increased 35 lbs to a level which was above her normal healthy weight. Resting pulse was 54 beats/min. The thyroid gland that had begun to decrease in size was now larger than before the treatment.

1) Why did her thyroid gland re-enlarge?

A) The re-enlargement of the thyroid gland reflects the increased negative feedback on the hypothalamus
B) The re-enlargement of the thyroid gland reflects the increased negative feedback on the anterior pituitary gland
C) The re-enlargement of the thyroid gland reflects the stimulatory actions of T3 and T4 on the thyroid gland
D) The re-enlargement of the thyroid gland reflects the increased intake of iodine in the diet
E) The re-enlargement of the thyroid gland reflects the stimulatory effects of increased TSH

2) What would a severe restriction of iodine in this patient's diet do?

A) It may make symptoms better before treatment with thiouracil, but it would make symptoms worse after treatment with thiouracil.
B) It may have made symptoms worse before treatment with thiouracil, but it would make symptoms better after treatment with thiouracil.
C) It would have no effect on this patient before or after treatment with thiouracil
D) It would overcome the actions of thiouracil and made this treatment ineffective