Question

Read the overview and complete the activities that follow.

A 41-year-old African American male complaining of feeling sick over the past 3 months was seen by his physician. His main complaints were feeling very weak and having periodic bouts of dizziness. The patient was 6' 1" and weighed 155 pounds. He reported that he was not always this thin, and said that he lost over 20 pounds during the previous 3 months. His body temperature was 98.6 ˚F. An examination of his oral cavity showed no redness or swelling, but his gums and oral mucosa were darker in color than normal (hyperpigmentation). His blood pressure when seated was 100 mmHg systolic pressure/70 mmHg diastolic pressure (normal 120/80 mmHg), but when the nurse tried to take a second reading while he was standing systolic pressure fell to 80 mmHg and diastolic pressure fell too low to be accurately determined. Blood was drawn, and the following results came back from the lab:

Serum [Na⁺] = 125 mEq/L (normal 135–148)
Serum [K⁺] = 6.5 mEq/L (normal 3.5–5.3)
Serum [Cl^-] = 98 mEq/L (normal 96–100)
Serum [HCO3^-] = 17 mEq/L (normal 20–26)
Serum [creatinine] = 1.5 mg/dL: (normal 0.7–1.4)
Serum pH = 7.31 (normal 7.35–7.45)
Serum [glucose] = 76 mg/dL (normal 80–110)

Which of the following is the most likely cause of the decreased serum [Na⁺] observed in this patient?

Decreased thyroid hormone secretion

Decreased cortisol secretion

Decreased aldosterone secretion

Decreased urine volume

Decreased sympathetic nervous system activity

Answer 1

Decreased aldosterone secretion.

This is a case of primary adrenal insufficiency due to failure of adrenal gland to secrete hormones.. .so due to feedback regulation ACTH from pituitary increases and along with ACTH melanocyte stimulating hormone also increases leading to hyperpigmentation.. ..

Decreased aldosterone leads to low sodium levels and increased potassium levels in the blood and can contribute to orthostatic hypotension seen in this patient..