NUA 5950 Chapter 13 - Endocrine Rockhurst University
Chapter 13 - Endocrine
I. Glandular Anatomy and Hormonal Functions
The endocrine system secretes chemical messengers (hormones) directly into the bloodstream to affect
specific target cells.
Hypothalamus and Pituitary Gland
● Hypothalamus: Often considered the master controller, it secretes releasing and inhibiting hormones
that regulate the pituitary gland. These include TRH (stimulates TSH), CRH (stimulates ACTH), and
GHRH (stimulates GH) .
● Anterior Pituitary: Synthesizes and secretes six major hormones, including GH (growth), TSH (thyroid
stimulation), ACTH (adrenal stimulation), Prolactin (breast development/milk), FSH, and LH
(reproduction) .
● Posterior Pituitary: Stores and releases ADH (water reabsorption) and Oxytocin (uterine contractions
and milk ejection) .
Thyroid and Parathyroid
● Thyroid Gland: Produces T3 and T4, which require iodine and regulate the body’s metabolic rate . It
also produces Calcitonin, which lowers blood calcium.
● Parathyroid Glands: Secrete PTH, which increases serum calcium by acting on the bones, intestines,
and kidneys.
Pancreas, Adrenals, and Gonads
,● Pancreas (Islets of Langerhans): A cells secrete glucagon (increases glucose), B cells secrete
insulin (lowers glucose), and D cells secrete somatostatin (delays nutrient absorption) .
, ● Adrenal Glands: The medulla secretes catecholamines (epinephrine/norepinephrine) for "fight or
flight" . The cortex secretes glucocorticoids (cortisol), mineralocorticoids (aldosterone), and androgens
.
● Gonads: Testes produce testosterone; ovaries produce estrogen and progesterone .
II. Clinical Assessment and Physical Examination
Endocrine disorders often manifest through systemic symptoms that affect multiple organs.
Common Chief Complaints
● Fatigue: Often chronic and associated with both hyperthyroidism and hypothyroidism, diabetes, and
adrenal insufficiency.
● Palpitations: Rapid or irregular heartbeats common in thyroid disease and pheochromocytoma.
● Integumentary/Facial Changes: * Thyrotoxicosis: May cause a bright-eyed "stare," lid lag,
exophthalmos (protruding eyes), and thin hair.
○ Cushing’s Syndrome: Characterized by "moon face," "buffalo hump," purple striae on the
abdomen, and thinning skin.
○ Hypothyroidism: Can cause periorbital edema, thick puffy skin, and brittle hair.
Physical Exam Highlights
● Thyroid Inspection: Observe the patient swallowing a sip of water; the thyroid tissue and cartilage
should move upward symmetrically.
● Thyroid Palpation: Can be performed via an anterior or posterior approach . A soft gland may indicate
Graves' disease, while a firm gland may suggest Hashimoto’s thyroiditis or malignancy.
● Auscultation: A soft rushing sound (bruit) heard over the thyroid may indicate thyrotoxicosis.
III. Diagnostic Testing
● TSH: Considered the most sensitive test for thyroid function (Normal: 0.4–4 mIU/mL).
● Thyroxine (T4): Total T4 (TT4) helps rule out hypo- or hyperthyroidism.
● Radioactive Iodine Uptake: A high percentage of uptake after 24 hours indicates an overactive gland.
● Fluid Deprivation Test: Used specifically to diagnose diabetes insipidus.
IV. Special Populations
● Neonatal: Thyroid hormone is critical for brain development; congenital hypothyroidism can cause
feeding difficulties, a hoarse cry, and stunted growth if untreated .
● Pediatric: In children, hyperthyroidism may present as accelerated linear growth.
● Geriatric: Endocrine symptoms are often subtle; hyperthyroidism may present as "apathetic," where
the patient is lethargic rather than hyperactive, often leading to a misdiagnosis of depression.
Endocrine Hormones: Sources and Major Actions
The endocrine system relies on a complex hierarchy where the hypothalamus and pituitary gland regulate
target organs throughout the body.
Chapter 13 - Endocrine
I. Glandular Anatomy and Hormonal Functions
The endocrine system secretes chemical messengers (hormones) directly into the bloodstream to affect
specific target cells.
Hypothalamus and Pituitary Gland
● Hypothalamus: Often considered the master controller, it secretes releasing and inhibiting hormones
that regulate the pituitary gland. These include TRH (stimulates TSH), CRH (stimulates ACTH), and
GHRH (stimulates GH) .
● Anterior Pituitary: Synthesizes and secretes six major hormones, including GH (growth), TSH (thyroid
stimulation), ACTH (adrenal stimulation), Prolactin (breast development/milk), FSH, and LH
(reproduction) .
● Posterior Pituitary: Stores and releases ADH (water reabsorption) and Oxytocin (uterine contractions
and milk ejection) .
Thyroid and Parathyroid
● Thyroid Gland: Produces T3 and T4, which require iodine and regulate the body’s metabolic rate . It
also produces Calcitonin, which lowers blood calcium.
● Parathyroid Glands: Secrete PTH, which increases serum calcium by acting on the bones, intestines,
and kidneys.
Pancreas, Adrenals, and Gonads
,● Pancreas (Islets of Langerhans): A cells secrete glucagon (increases glucose), B cells secrete
insulin (lowers glucose), and D cells secrete somatostatin (delays nutrient absorption) .
, ● Adrenal Glands: The medulla secretes catecholamines (epinephrine/norepinephrine) for "fight or
flight" . The cortex secretes glucocorticoids (cortisol), mineralocorticoids (aldosterone), and androgens
.
● Gonads: Testes produce testosterone; ovaries produce estrogen and progesterone .
II. Clinical Assessment and Physical Examination
Endocrine disorders often manifest through systemic symptoms that affect multiple organs.
Common Chief Complaints
● Fatigue: Often chronic and associated with both hyperthyroidism and hypothyroidism, diabetes, and
adrenal insufficiency.
● Palpitations: Rapid or irregular heartbeats common in thyroid disease and pheochromocytoma.
● Integumentary/Facial Changes: * Thyrotoxicosis: May cause a bright-eyed "stare," lid lag,
exophthalmos (protruding eyes), and thin hair.
○ Cushing’s Syndrome: Characterized by "moon face," "buffalo hump," purple striae on the
abdomen, and thinning skin.
○ Hypothyroidism: Can cause periorbital edema, thick puffy skin, and brittle hair.
Physical Exam Highlights
● Thyroid Inspection: Observe the patient swallowing a sip of water; the thyroid tissue and cartilage
should move upward symmetrically.
● Thyroid Palpation: Can be performed via an anterior or posterior approach . A soft gland may indicate
Graves' disease, while a firm gland may suggest Hashimoto’s thyroiditis or malignancy.
● Auscultation: A soft rushing sound (bruit) heard over the thyroid may indicate thyrotoxicosis.
III. Diagnostic Testing
● TSH: Considered the most sensitive test for thyroid function (Normal: 0.4–4 mIU/mL).
● Thyroxine (T4): Total T4 (TT4) helps rule out hypo- or hyperthyroidism.
● Radioactive Iodine Uptake: A high percentage of uptake after 24 hours indicates an overactive gland.
● Fluid Deprivation Test: Used specifically to diagnose diabetes insipidus.
IV. Special Populations
● Neonatal: Thyroid hormone is critical for brain development; congenital hypothyroidism can cause
feeding difficulties, a hoarse cry, and stunted growth if untreated .
● Pediatric: In children, hyperthyroidism may present as accelerated linear growth.
● Geriatric: Endocrine symptoms are often subtle; hyperthyroidism may present as "apathetic," where
the patient is lethargic rather than hyperactive, often leading to a misdiagnosis of depression.
Endocrine Hormones: Sources and Major Actions
The endocrine system relies on a complex hierarchy where the hypothalamus and pituitary gland regulate
target organs throughout the body.
