70

70 CASE 70


A 38-year-old man is transported to the emergency department after having fainted at home.


The patient is a recent immigrant to the United States from equatorial Africa. During the past year he has become progressively weak and lethargic. He had tuberculosis 2 years ago, which was managed medically. The patient has had vomiting and diarrhea for the past 24 hours, and his family reports a weight loss of about 15 pounds during the past 3 months.



PHYSICAL EXAMINATION



VS: T 39.5°C, P 120/min, R 28/min, BP 80/65 mm Hg

PE: Patient is disoriented and is having difficulty remaining conscious. He is sweating and appears malnourished. Excessive pigmentation is present on the lips and gums and in the palmar creases of the hands.


LABORATORY STUDIES



Plasma studies:
• Sodium: 135 mEq/L (normal: 136-145 mEq/L)

• Potassium: 5.2 mEq/L (normal: 3.5-5.0 mEq/L)

• Chloride: 100 mEq/L (normal: 95-105 mEq/L)

• Blood urea nitrogen: 25 mg/dL (normal: 7-18 mg/dL)

Tetracosactide test: Resting plasma cortisol 50 nmol/L (normal at 4:00 PM: 82-413 nmol/L); 60 minutes after injection: Increased to 100 nmol/L (normal response: increase > 330 nmol/L)


DIAGNOSIS


Acute adrenal insufficiency (Addisonian crisis)



PATHOPHYSIOLOGY OF KEY SYMPTOMS


The patient’s symptoms affect a variety of systems. Hypotension indicates a defect of the cardiovascular and/or renal systems. The abnormal electrolytes suggest defects in the renal or mineralocorticoid systems. Progressive weight loss, vomiting, and diarrhea indicate abnormal metabolic regulation. The adrenal cortex is an endocrine gland that impacts all of these systems.


Adrenocortical insufficiency, first described by the physician Addison, is characterized by destruction of adrenal tissue or by defective adrenal steroid synthesis. The clinical symptoms result from the lack of aldosterone, a lack of cortisol, or an overproduction of pituitary adrenocorticotropic hormone (ACTH). Adrenocortical insufficiency may be mild, but an additional stress such as an infection may cause a sudden worsening of the condition, called an Addisonian crisis.


Cortisol production is essential to allow the body to adjust to stress. Plasma cortisol levels show a wide diurnal variation, being highest in the morning and lowest at night.


Cortisol increases the plasma glucose level by stimulating hepatic gluconeogenesis and by diminishing tissue glucose uptake. Cortisol suppresses the immune system activity and causes deposition of fat and glycogen, particularly in the trunk area. The absence of cortisol impairs metabolic regulation. Low plasma cortisol leads to hypoglycemia, weakness, fatigue, and weight loss. The complete absence of cortisol is fatal.


Cortisol exhibits a marked diurnal variation in plasma levels, with the highest level at 8 AM being more than four times as high as the lowest level at night (Fig. 70-1). Consequently, a patient’s plasma cortisol level must be matched against an appropriate range for that time of day.


image

FIGURE 70–1 Typical pattern of cortisol concentration during the day. Note the oscillations in secretion as well as a daily secretory surge an hour or so after awaking in the morning.

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Jul 4, 2016 | Posted by in PHYSIOLOGY | Comments Off on 70

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