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Chapter 31
Disorders of Endocrine Function
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
HypothalamusPituitary Axis
• Releasing hormones
from hypothalamus
tell the pituitary what
to release into the
blood
• Trophic hormones
from the pituitary tell
specific peripheral
glands to grow and
produce their
hormones
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Hormone Disorders
Tertiary: abnormality in
stimulation from the
hypothalamus
Secondary: abnormality
in stimulation from the
pituitary
Primary: abnormality in
the gland
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Pituitary
Hormones
Growth
hormone
FSH
and LH
TSH
stimulate
gonads
stimulates
thyroid
ACTH
stimulates
adrenal
cortex
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Question
Which hormone(s) is/are secreted by the ovaries and
testes?
a. GH
b. FSH and LH
c. TSH
d. ACTH and GH
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Answer
b. FSH and LH
Rationale: Gonads are sex organs (ovaries and testes).
These organs secrete follicle-stimulating hormone (FSH)
and luteinizing hormone (LH).
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
The Hypothalamus Controls Growth
Hormone Release
Hypothalamus
• GH secretion stimulated by:
– Hypoglycemia, fasting,
starvation
GHRH
stimulates
– Stress
Somatostatin
inhibits
• GH inhibited by:
– Increased glucose
levels, free fatty acid
release, and obesity
– Cortisol
Anterior pituitary
Growth
hormone
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Functions of Growth Hormone
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Growth Hormone Deficiency
• Idiopathic GH deficiency
– Lacks hypothalamic GHRH
• Pituitary tumors, agenesis of the pituitary
– Cannot produce GH
• Laron-type dwarfism
– Hereditary defect in IGF production
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Growth Hormone Excess
• In childhood: gigantism
• In adulthood: acromegaly
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Question
Tell whether the following statement is true or false.
GH deficiency may result in dwarfism.
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Answer
True
Rationale: Laron-type dwarfism is caused by a genetic
inability to produce normal amounts of GH.
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
The Hypothalamus Controls Gonadal
Hormone Release
hypothalamus
• Excessive GnRH secretion
can be stimulated by:
– Hypothalamic tumors
– Pituitary tumors
• Giving high levels of GnRH
causes the pituitary to
become less responsive and
reduces the effects of
abnormal GnRH secretion
GnRH
stimulates
anterior pituitary
FSH
LH
production of gametes
and gonadal hormones
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Thyroid Control
• Thyroid releases T3
and T4
• Both are carried by
binding proteins
• T3 stimulates metabolism
• T4 is inactive until
converted into T3 in the
tissues
• Both exert negative
feedback on the
hypothalamus
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Thyroid Insufficiency Due to Lack of I
• T3 and T4 are
not made
• There is no negative
feedback to the
hypothalamus
• TRH and TSH continue
to be made
• If it is able, the thyroid
will grow in response to
the TSH
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Thyroid Imbalances
• Hypothyroidism
– Congenital
– Acquired
º Hashimoto thyroiditis
º Thyroidectomy
• Hyperthyroidism (thyrotoxicosis)
– Graves disease
– Thyroid tumors
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Question
Tell whether the following statement is true or false.
Simple goiter is caused by increased production of thyroid
hormone.
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Answer
False
Rationale: Simple goiter is the result of iodine (I)
insufficiency. Since I is necessary in order to produce
thyroid hormone, a deficiency results in low serum levels
of T3 /T4. This causes TSH to stimulate the thyroid gland
to make more hormone (which it cannot do because it
needs I). The cells of the thyroid gland hypertrophy in an
effort to function (make thyroid hormone).
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Major Adrenal Cortical Hormones
Hypothalamus
Corticotropin-releasing
hormone (CRH)
Negative
feedback
Anterior pituitary
Negative
feedback
Adrenal corticotrophic
hormone (ACTH)
Adrenal
cortex
Cortisol
Testosterone
Aldosterone
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Actions of Cortisol
cortisol
catabolism increased
plasma
proteins
increased
muscle
breakdown
free fatty
acids
increased
immune/
inflammatory
systems
suppressed
SNS response
increased
blood glucose
increased
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Adrenal Cortical Disorders
• Adrenal cortical insufficiency: inability to make all three
hormones
– Primary adrenal cortical insufficiency (Addison disease)
– Secondary adrenal cortical insufficiency
– Acute adrenal crisis
• Excessive adrenal secretion
– Glucocorticoid hormone excess (Cushing syndrome)
– Hyperaldosteronism
• Congenital adrenal hyperplasia
– Decreased cortisol synthesis; other hormones may be
increased or decreased
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Scenario
Three men have adrenal problems.
• One has hypoaldosteronism, one has an inability to make
cortisol, and one has an inability to make testosterone.
Question:
• Which of them is most likely to develop:
• Hypotension?
• High CRH levels?
• Hypoglycemia?
• Hypervirilization?
• Decreased libido?
• Hyperkalemia?
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Scenario
Two women have benign pituitary tumors.
• One woman has lost weight and complains of being
hot all the time; she presents as thin and nervous,
with tachycardia and exophthalmos
• The second woman has gained weight in her
abdomen and presents with a round face and thin
arms and legs with stretch marks; she says that at
her last checkup her doctor told her she was
prediabetic
Question:
• What hormones are being secreted by the pituitary
tumors in these patients? Why?
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins