A 50yearold female complains of excessive sweating and heart

A 50-year-old female complains of excessive sweating and heart palpitations. On physical examination, her skin is warm and moist, pulse 120/minute, and blood pressure 150/95 mm Hg. She has noticed excessive watering and a foreign body sensation in her eyes. A blood test for thyroid function yields the following results.

          Free T₄ = 3.20 ng/dL

          TSH = <0.03 mU/mL

1.   Based on the results provided, how would you assess the patient’s thyroid function?

2.   What are three common causes of hyperthyroidism?

3.   What would be the next step in thyroid testing to further pinpoint the cause of the patient’s symptoms? Explain your reasoning.

4.   The patient tests positive for TRAb. Based on these results, what would be the patient’s diagnosis? Explain the pathophysiology of this disease.

5.   What would be the expected results of the following tests in this case?

a.    T₄

b.    T₃

6.   Suggest three treatment strategies for hyperthyroidism.

7.   Suggest an explanation for the low TSH value.

8.   What is a major function of thyroid hormones?

9.   What laboratory test(s) would best differentiate primary and secondary hyperthyroidism?

10. What is the formula for calculating free thyroxin index? What is its diagnostic utility in diagnosing thyroid disorders?

11. What screening tests for congenital hypothyroidism are commonly performed?

Solution

1. Normal TSH in adult (50years) is 0.4-4.2 mlU/L. A very low value of this TSH is indicative of overreactive thyroid gland i.e, hyperthyroidism.

2.Three common causes of hyperthyroidism are : a.autoimmune disease (Grave\'s disease), b. goiter, c.   excessive iodine in body.

3. To further pinpoint the cause of patient\'s symptoms, T4 level is tested. In hyperthyroidism, high levels of free thyroid hormone will suppress TSH levels, but the degree of suppression of TSH does not always reflect the severity of the hyperthyroidism.Therefore, a test of free thyroid hormone levels is usually recommended. If the Free T4 is normal, the free T3 should be checked as it is the first hormone to increase in early hyperthyroidism.

4. TSH receptor antibody (TRAb) patients are mediators of thyroid stimulation in Grave\'s disease.
Pathophysiology : Grave\'s ophthalmopathy, pernicious anemia, diabetes mellitus 1, systemic sclerosis, Myasthenia gravis.
5a. T4 - > 1.9 ng/mL
b. T3 - > 132 ng/dL

6. Three treatment strategies are : a. Antithyroid medicines, b.Radioactive iodine, c.Surgery.

8. The major function of thyroid hormone is to increase the basal metabolic rate, regulate growth hormone and increase catecholamine effect.

9. a.TSH primary : increased
secondary: decreased
b.Baseline and dynamic anterior pituitary hormone testing for deficiencies and overproduction