Why the remaining adrenal gland fails
During months of tumor-driven cortisol excess, high cortisol suppresses pituitary ACTH through negative feedback. Without ACTH stimulation, the remaining (right) adrenal gland becomes dormant and its cortisol-producing zone shrinks. When the tumor is removed, the main source of cortisol disappears abruptly, and the dormant gland cannot respond quickly. Unless glucocorticoid is replaced, cortisol falls suddenly after removal of a cortisol-secreting tumor, causing adrenal insufficiency. She has received no glucocorticoid since the operation.
Matching the findings
Cortisol is needed to maintain vascular tone and the response to stress, so its loss causes hypotension (86/52 mmHg) and tachycardia (116 beats/min), together with weakness and nausea. Low cortisol also impairs free water excretion, leading to hyponatremia (131 mEq/L). Her potassium remains normal at 4.6 mEq/L because aldosterone is regulated mainly by the renin–angiotensin system, not ACTH, so mineralocorticoid function is preserved.
| Possibility | Expected findings | Her data |
|---|
| Adrenal insufficiency | Hypotension, tachycardia, low sodium, normal potassium | Matches |
| Postoperative bleeding | Rising drain output, falling hemoglobin | Drain 30 mL/12 h; hemoglobin stable |
| Septic shock | Fever or hypothermia, infection source | Temperature 37.2 °C |
| Dehydration from fasting | Sodium normal or high | Sodium low |
Why the other problems are less likely
Acute bleeding into the operative bed usually shows rising drain output or a falling hemoglobin; her drain has only 30 mL of serosanguineous fluid in 12 hours and her hemoglobin has barely changed from 12.4 to 12.1 g/dL. Bleeding also would not explain the low sodium. Septic shock on the first day is unlikely with a normal temperature and no infection source. Dehydration from fasting tends to raise sodium. Watch out! Hypotension after surgery is often assumed to be bleeding; check whether the drain and hemoglobin actually support that.
Exam takeaway
After removal of a cortisol-secreting adrenal tumor, clients usually receive glucocorticoid replacement, which is tapered over months while the remaining gland recovers. The nurse reports these findings immediately so that glucocorticoid can be given. Key point! Hypotension, tachycardia, hyponatremia, and weakness after adrenalectomy for Cushing syndrome suggest adrenal insufficiency.