Case Study Week 1

EJ WEEK ONE CASE STUDY

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Week 1 Case Study

Emily Jamieson

MGH Institute of Health Professions

EJ WEEK ONE CASE STUDY

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Week 1 Case Study

1) The two hormones that are commonly referred to as “thyroid hormone” are thyroxine (T4)

and triiodothyronine (T3). They are both active hormones secreted by the thyroid and differ

only in the number of iodine atoms bound to their core (two linked tyrosine amino acid

molecules) (Marieb & Hoehn, 2013, p. 318). Thyroxine or T4 has four bound iodine atoms

and is secreted by the thyroid follicles; triiodothyronine or T3, on the other hand, has only

three bound iodine atoms and is formed primarily at target tissues (an iodine atom is cleaved

from thyroxine to produce triiodothyronine). T3 is considered the “active” form of T4 and is,

thus, far more potent. Both of these hormones act to maintain metabolism, body temperature

and blood pressure (Marieb & Hoehn, 2013, p. 318).

2) An overactive thyroid can cause weight loss, sweating and elevated heart rate, because the

thyroid, through the action of its hormones, is responsible for maintaining all the functions

that are irregular in Krista’s case. Weight loss is a function of an overactive metabolism (the

body is breaking down more nutrients than it is absorbing) and excessive sweating comes

from intense production of heat that comes from her increased metabolic activity. Finally,

her elevated heart rate is due to an overproduction of both T3 and T4, both of which rapidly

increase cardiac output and blood pressure (Marieb & Hoehn, 2013, p. 318).

3) Thyroid-stimulating hormone or TSH is secreted by the anterior lobe of the pituitary gland.

The action of TSH is to stimulate the thyroid to produce both T3 and T4.

4) The role of TSH is primarily regulatory; the pituitary gland secretes TSH into the

bloodstream which stimulates the thyroid to produce and release both T3 and T4

(Thompson, 2014). The levels of T3 and T4 are maintained and detected by the...