What condition may Joan develop if she abruptly stops her corticosteroid medication?

When a patient abruptly stops corticosteroid medication, particularly after long-term use, the body can experience a sudden and severe deficiency of cortisol. This condition is known as an Addisonian crisis, characterized by symptoms such as severe fatigue, dizziness, hypotension, and potentially life-threatening electrolyte imbalances.

Corticosteroids mimic the effects of cortisol, which regulates essential functions in the body, including stress response and metabolism. Prolonged use of these medications suppresses the adrenal glands' ability to produce cortisol naturally. Therefore, when the medication is withdrawn too quickly, the body is unable to compensate for the lack of cortisol, leading to the acute onset of symptoms associated with adrenal insufficiency.

The other conditions mentioned in the choices are not directly related to the abrupt cessation of corticosteroids. Myxedema crisis pertains to severe hypothyroidism, diabetes insipidus involves problems with antidiuretic hormone (ADH), and hypoparathyroidism involves deficiency of parathyroid hormone, none of which result from stopping corticosteroid therapy. Thus, the most appropriate condition to develop from abruptly stopping corticosteroid medication is an Addisonian crisis.