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CASE FILES: BIOCHEMISTRY
A N SW E R S TO C A SE 47: A C R O M E G A L Y
Summary:
A 36-year-old male comes into the physician’s office with height
greater that the 95th percentile, coarse facial features (frontal bossing,
macroglossia, large nose), oily skin, organomegaly, and thickened soft tissue
of the hand and feet.
Diagnosis: Acromegaly
Biochemical mechanism: Excess and autonomous secretion of growth
hormone
C L IN IC A L C O R R E L A T IO N
Acromegaly is a disorder with excessive growth hormone (GH), usually as a
result of autonomous secretion from a nonmalignant anterior pituitary tumor.
When acromegaly affects individuals prior to bone growth plate closure,
giantism may result; after the bone growth plates close, the patients usually
develop coarse features and large hands and feet. The diagnosis is confirmed
by demonstrating the failure of GH suppression within 1 to 2 hours of an oral
glucose load (75 gm), because GH is usually decreased with glucose. As a con-
sequence of the pulsatility of GH secretion, a single random GH level is not
useful for diagnosis. Morbidity can ensue because of diabetes or hypertension.
The most feared complications are cardiac in nature, which may affect up to
30 percent of patients. Cardiac arrhythmias, cardiomyopathy, left ventricular
hypertrophy, hypertension, and coronary heart disease can be present.
Arrhythmias can be associated with cardiomyopathy or coronary heart disease.
The primary therapy of acromegaly is surgical, but there is often only partial
response. Thereafter somatostatin analogues or dopamine agonists are used,
and as a last line of therapy, radiation.
A PPR O A C H TO G R O W T H H O R M O N E
A B N O R M A L IT IE S
O bjectives
1.
Be familiar with growth hormone regulation and function.
2.
Know about the association with other hormonal problems (diabetes
mellitus [DM], thyroidism, etc.).
D efinitions
Ghrelin: A 28-amino acid peptide that is octanoylated on serine-3. Ghrelin
is synthesized and secreted by endocrine cells in the stomach and will
bind to somatotrophic cells in the anterior pituitary to promote the
release of growth hormone (somatotropin).
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