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CASE FILES: BIOCHEMISTRY
A N SW E R S TO C A SE 50: C U SH IN G SY N D R O M E
Summary:
A 32-year-old female with irregular menses, hirsutism, mood
swings, weight gain, truncal obesity, hypertension, abdominal striae, ecchy-
moses, and elevated cortisol levels.
Diagnosis: Cushing Syndrome
Elevated ACTH level: Likely cause of adrenal hyperplasia from
ACTH-producing tumor
C L IN IC A L C O R R E L A T IO N
This patient presents with many of the classic findings of Cushing syndrome.
Adrenal hyperplasia can be caused by excessive stimulation from ACTH (pitu-
itary or ectopic production) or from a primary adrenal problem such as adenomas/
carcinomas. In addition to above symptoms, patients with Cushing syndrome are
also at risk for osteoporosis and diabetes mellitus (DM). The diagnosis is con-
firmed with elevated cortisol levels after a dexamethasone suppression test.
Treatment depends on the underlying etiology and is often surgical.
A PPR O A C H TO C U SH IN G SY N D R O M E
O bjectives
1.
Describe the biosynthesis of steroids in the adrenal gland.
2.
Explain from a biochemical standpoint why hypertension is a common
consequence of Cushing syndrome.
D efinitions
Abdominal striae: Stretch marks of the abdominal region.
ACTH (adrenocorticotropic hormone or corticotropin): Hormone pro-
duced in the anterior pituitary, which stimulates adrenal production of
cortisol.
Adenoma: Any benign tumor of glandular origin; typically found in the
adrenal, pituitary, and thyroid glands (note: once an adenoma has pro-
gressed to malignancy, it is referred to as an adenocarcinoma).
CRH (corticotropin-releasing hormone): Hormone produced in the
hypothalamus, which stimulates release of ACTH from the anterior
pituitary.
Cushing disease: A specific form of Cushing syndrome, which is caused
by an ACTH-secreting pituitary adenoma; represents approximately
66 percent of all cases of Cushing syndrome. Because of structural simi-
larities with melanocyte-stimulating hormone (MSH), excess ACTH from
pituitary adenomas can induce dermal hyperpigmentation.
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