Endocrine Case Study 5*

The Case of the Sweaty Salesman


Michael is a thirty year old salesman who spends approximately 4 days each week traveling to visit with customers in his region. During his routine physical he casually mentions to his physician that he seems to be sweating more profusely than normal and most rooms that once were comfortable are now too "hot". He thought that it was simply due to the change in seasons and companies being slow to turn down the thermostats from the winter temperatures, however this problem seems to persist even when he is at home. Michael also reports that he seems to be loosing weight even though his appetite has increased. He also complains that he has a shortened attention span and that he always wants to be moving around. Despite the fact that he feels fatigued, Michael claims to have difficulty sleeping and seems to have more frequent bowel movements, occasionally accompanied by diarrhea. The physician checks Michael's medical history and finds that indeed he has lost 15 pounds since his last physical. Michael has a negative history for chronic illnesses, does not smoke, and has a low risk for cardiovascular disease. He does however have a positive family history for autoimmune diseases.


Results of Michael's physical examination were within normal ranges with the exception of the following: he demonstrated tachycardia, loud heart sounds, and apparent cardiac arrhythmias accompanied by slight hypertension. These arrhythmias were confirmed by electrocardiogram to be ventricular in origin. Michael's eyeballs appeared large and protruding and his hair was fine and soft. He was also beginning to demonstrate some degree of alopecia. Michael was also observed to have palmar erythema. Palpation of the neck revealed the presence of goiter. Results of blood tests indicated elevated concentrations of thyroid hormones (thyroxin and triiodothyronine), hypercalcemia, and decreased circulating concentrations of lipids. Based on the physical characteristics and the results of the blood tests, Michael's physician suspected that Michael was suffering from some form of GraveÕs Disease and sent him to an endocrinologist to confirm the initial diagnosis.


General Questions

1.)  Desribe the mechanism by which a peptide hormone initiates a cell response; a steroid hormone initiates a cell response. How are they the same? How are they different? Give a specific example of each and state their effect on the human body.


2.) Compare the hormonal controls of the male reproductive cycle with the hormonal controls of the female reproductive cycle.  How are they the same?  How are they different?

Specific Questions:


1.             Thyroid hormones exert their effects on cells in a manner similar to steroid hormones; describe the mechanism of action of thyroid hormones.


2 .             Elaborate on the cause of GraveÕs Disease.


3.             Why would an imbalance in thyroid hormones have such widespread effects on the body?


4.              Why was goiter observed in MichaelÕs case?


5.             Why would calcium homeostasis be impaired in response to removal of the thyroid gland?


6.             What treatment options are available to a person with GraveÕs Disease?


7.             Given that Michael and his wife may want to have more children, why was radioisotopic destruction of the thyroid gland ruled out?


*Adapted from Essentials of Anatomy and Physiology; Seeley, Stephens and Tate, McGrawHill, 2003