Download - Patho2 chapter40 student1
Disorders of Endocrine Function
Chapter 40
Etiology of Endocrine Disorders• Hyposecretion or hypersecretion can occur in the:
– Hypothalamus/pituitary– Hormone-producing gland– Target tissue
• Etiology can be:– Congenital– Infectious– Autoimmune– Neoplastic– Idiopathic– Iatrogenic
Endocrine Disorders
Elevated or Depressed Hormone Levels
• Failure of feedback systems• Dysfunction of an endocrine gland• Secretory cells are unable to produce, obtain, or
convert hormone precursors• The endocrine gland synthesizes or releases excessive
amounts of hormone or not enough hormone• Increased hormone degradation or inactivation• Ectopic hormone release• Target cell failure
• Endocrine disorders involving control by anterior pituitary gland are classified as:
– Primary: intrinsic malfunction of the hormone-producing target gland
– Secondary: malfunction of the hypothalamus/pituitary cells that control the hormone-producing target gland
Endocrine Disorders: Classification
Alterations of the Hypothalamic-Pituitary System
Endocrine Disorders
Diseases of the Anterior Pituitary
• Hypersecretion of growth hormone (GH)– Acromegaly
• Hypersecretion of GH during adulthood• (cause: GH-secreting pituitary adenoma)
– Gigantism• Hypersecretion of GH in children & adolescents
Diseases of the Anterior PituitaryGiantism:
Hypersecretion of growth hormone (GH)
(excess somatotropin [GH] BEFORE epiphyseal closure)
Diseases of the Anterior Pituitary• Acromgaly:
Hypersecretion of growth hormone (GH)
(excess somatotropin [GH] AFTER epiphyseal closure)
Thyroid Gland Disorders
• Hypothyoidism– Congenital – Acquired
• Hyperthyroidism
Thyroid Hormone Disorders
• CONGENITAL HYPOTHYROIDISM (cretinism) is typically due to thyroid dysgenesis
• Majority are PRIMARY, due to intrinsic dysfunction of the thyroid gland
• PRIMARILY LYMPHOCYTIC THYROIDITIS (Hashimoto or autoimmune thyroiditis)
• Irradiation of the thyroid gland
• Surgical removal of thyroid tissue
• Iodine deficiency
HypothyroidismAcquired
CretinismCongential hypothyroidism: can be endemic (iodine
deficiency), genetic, or sporadic
Delayed bone maturation, puberty, mental retardation, abdominal protrusion with umbilical hernia
A 3-month-old male was diagnosed with congenital hypothyroidism. If left untreated, the child would have:
A. mental retardation and stunted growth.B. increased risk of childhood thyroid cancer.C. hyperactivity and attention deficit disorder.D. liver, kidney, and pancreas failure.
Primary Hypothyroidism
• Iodine is essential for T3 and T4 synthesis
• Deficiency in iodine leads to lack of T3/T4 but does not affect
thyroglobulin levels
• Insufficient hormone available to inhibit secretion of TSH
• Increased TSH causes thyroid cells to secrete large amounts of
thyroglobulin, which leads to a goiter
ETIOLOGY AND PATHOGENESIS: Hypothyroidism:
GOITER
Many vegetables are goiterogens
Secondary hypothyroidism is caused by defects in TSH
production and can result from:• Severe head trauma
• Cranial neoplasms
• Brain infections
• Cranial irradiation
• Neurosurgical procedures
ETIOLOGY AND PATHOGENESIS: Hypothyroidism:
Clinical ManifestationsInfants
• Dull appearance, thick,
protuberant tongue, and thick
lips result in feeding difficulties
• Prolonged neonatal jaundice
• Poor muscle tone
• Bradycardia, mottled extremities
• Umbilical hernia
• Hoarse cry
Children/Adults
• Decreased basal metabolic rate
• Weakness, lethargy, cold intolerance,
decreased appetite
• Bradycardia, narrowed pulse pressure,
and mild/moderate weight gain
• Elevated serum cholesterol and
triglycerides
• Enlarged thyroid, dry skin, constipation
• Depression, difficulties with
concentration/memory
• Menstrual irregularity
Hashimoto’s thyroiditis
• Chronic lymphocytic thyroiditis• Infiltration by lymphocytes• Destruction of thyroid by antibodies• Goiter formation is common• Can occur with other autoimmune diseases: Type 1 DM, vitiligo
CLINICAL FEATURES of Hashimoto’s Thyroiditis
• Onset of disease – 30-60 years of age
• 5 times more common in females than males
• Patients have T4 and TSH
• Patients have enlarged thyroid (goiter)
• Symptoms include:– Dry skin, tiredness, weight gain, puffy face, intolerance to cold,
mild depression
• Treatment – thyroid hormone replacement
Hypothyroidism: characteristic sign of long-standing disease
Myxedema• Severe or prolonged thyroid deficiency • Accumulation of glycosaminoglycans in
interstitial spaces
Myxedema (coma)
• Sluggishness• Cool skin,
↑cholesterol
• Primary hypothyroidism will manifest as elevated TSH
• Low levels of T3 and T4 may not occur until later in the disease course
• Hypothalamic-pituitary dysfunction results in low levels of TSH and T4
DIAGNOSIS: Hypothyroidism
• Treatment goal is return of euthyroid state
• Oral levothyroxine is used to replace or supplement hormone production
• Resolution of symptoms occurs over weeks
• Intravenous levothyroxine used for myxedema coma
TREATMENT: Hypothyroidism:
• Primary—autonomous
• Secondary—mediated through stimulation of TSH
receptors by substances such as TSH
• Autoimmune—related to TSH receptor antibodies
Hyperthyroidism
What causes Hyperthyroidism?
• Pituitary adenoma
• Thyroid carcinoma
• Autoantibodies that bind and stimulate TSH receptors on
the thyroid gland leading to a diffuse toxic goiter (Graves
disease)
• Ingestion of thyroid hormone preparations or excessive
iodides
ETIOLOGY AND PATHOGENESIS: Hyperthyroidism
• Changes in behavior, insomnia, restlessness, tremor, irritability, palpitations, heat intolerance, diaphoresis, inability to concentrate that interferes with work performance
• Increased basal metabolic rate leads to weight loss, although appetite and dietary intake increase
• Amenorrhea/scant menses
CLINICAL MANIFESTATIONS: Hyperthyroidism
Graves Disease: autoimmunemost common form of hyerpthyroidism
Edema of orbit, exopthalmos, extrocular muscle weakness
Antibodies mimic TSH by binding to and activating TSH receptors
Clinical Features of Graves’ Disease
• Onset of disease – 20-50 years of age• 10 times more common in females than males• Patients have goiter with thyroid gland 2-3 times normal
size• Symptoms include:
– Nervousness, fatigue, weight loss; 50% have thyroid-associated ophthalmopathy with eyelid retraction and periorbital edema
• Treatment – anti-thyroid drugs, surgery, and radioactive iodine ablation
Graves’ Disease: Diagnosis
• Diagnosis often made on clinical symptoms alone
• Elevated T3 and T4; low TSH– Why?
Comparison of Graves’ disease and Hashimoto’s thyroiditis
HYPER HYPO
A 35-year-old female with Graves disease is admitted to a medical-surgical unit. Lab tests would most likely reveal:
A. high levels of circulating thyroid-stimulating antibodies.B. ectopic secretion of thyroid-stimulating hormone (TSH).C. low circulating levels of thyroid hormones.D. stimulation of thyroid-binding globulin.
Thyroid storm—form of life-threatening thyrotoxicosis that occurs when excessive amounts of thyroid hormones are acutely released into circulation
• Manifestations– Elevated temperatures, tachycardia, arrhythmias
– Extreme restlessness, agitation, and psychosis
– Vomiting, nausea, diarrhea, and jaundice
CLINICAL MANIFESTATIONS: Hyperthyroidism
DIAGNOSIS
Primary hyperthyroidism will manifest as:• Undetectable TSH levels
• Elevated serum T4 and T3
TREATMENTS: • Symptomatic relief: Beta blockers• Reduce circulating hormones: methimazole, propylthioricil
• More permanent treatment: surgical removal of thyroid, radioactive iodine
DIAGNOSIS: Hyperthyroidism:
Treatment of thyroid storm• Aggressive management to achieve metabolic
balance
• Antithyroid drugs are given followed by iodine administration
• Beta-blockers to alleviate symptoms
• Antipyretic therapy
• Fluid replacement
• Glucocorticoids
TREATMENT: Hyperthyroidism
Alterations of Thyroid Function: Table 40.2
Hypothyroidism Hyperthyroidism
Basal metabolic rate
Sympathetic ANS
Weight
Temp tolerance
GI function
Cardio/Respiratory function
Reproductive
Muscle tone
Appearance
General behavior
Adrenal Gland Disorders
1- Adrenal cortex:• Constitutes 90% of gland volume• Secrete steroid hormones (adrenocortical hormones):
- Mineralocorticoids (aldosterone) SALT- Glucocorticoids (cortisol) SUGAR- Adrenal androgens SEX
2- Adrenal medulla:• Secrete catecholamines:- Norepinephrine (NE, nonadrenaline)- Epinephrine (E, adrenaline)- Dopamine
Main hormones
Adrenal Gland
• Hypoadrenalism1- Primary adrenal insufficiency (Addison’s disease)2- Secondary adrenal insufficiency: CRH, ACTH, result from: - pituitary or hypothalamic disease. - long-term suppression of hypothalamic-pituitary-adrenal axis by
glucocorticoids adrenal atrophy.
• Hyperadrenalism1- Cushing’s syndrome: cortisol production2- Primary hyperaldosteronism (Conn’s syndrome): aldosterone
production 3- Congenital adrenal hyperplasia: caused by enzymatic
abnormalities in steroid synthesis.
Disorders of the Adrenal Cortex
Adrenocortical Insufficiency
Unable to produce adequate levels of cortisol
• Disorders of the adrenal cortex– Adrenocortical hypofunction
• PRIMARY: Addison disease– Destruction of the adrenal gland through:
• Idiopathic or autoimmune mechanisms• Tuberculosis, • Trauma or hemorrhage,• Fungal disease• Neoplasia
Adrenocortical Insufficiency
ENTIRE CORTEX
• Insufficient Adrenal hormones: chronic fatigue, muscle weakness, loss of appetite, weight loss, low BP, dehydration, cardiac arrythmias, bronzed appearance
Addison’s Disease: Clinical Manifestations
o By the time of the missile crisis, Kennedy was taking antispasmodics to control colitis; antibiotics for a urinary tract infection; and increased amounts of hydrocortisone and testosterone, along with salt tablets, to control his adrenal insufficiency and boost his energy.
• SECONDARY: Hypothalamic-Pituitary Dysfunction– usually iatrogenic, related to corticosteroid
therapy, which suppresses ACTH, CRH
– May also occur due to damage of the anterior pituitary or hypothalamus by tumors, infection, radiation, postpartum necrosis, trauma, or surgery
Adrenocortical Insufficiency
Addisonian crisis/acute adrenal insufficiency
• Life-threatening condition caused by inadequate levels of glucocorticoids and mineralocorticoids in circulation
• May occur with acute withdrawal of corticosteroids or due to periods of stress or trauma
Adrenocortical Insufficiency
Clinical manifestations
• Early signs include: – anorexia, – weight loss– weakness– malaise– apathy – electrolyte disturbances – hyperpigmentation of skin
• Diminished vascular tone, reduced cardiac output, inadequate circulating blood volume; can lead to cardiovascular collapse
Adrenocortical Insufficiency
Diagnosis
• Patient history and physical exam, decreased plasma cortisol levels• ACTH provocation test may be administered• Abdominal CT/MRI may be performed to evaluate the size of the
adrenal glands
Treatment
• Replacing the absent or deficient hormones in a manner that mimics natural production
• 2/3 of the daily dosage is given in the morning and 1/3 in the evening
• Treatment of adrenal crisis– Intravenous glucocorticoids
Adrenocortical Insufficiency
Alterations of Adrenal Function
Disorders of the adrenal cortex: HYPERCORTISOLISM
– Cushing disease• Excessive ANTERIOR
PITUITARY secretion of ACTH
– Cushing syndrome• Excessive level of
cortisol, regardless of cause
• PRIMARY adrenocortical hyperfunction due to disease of the adrenal cortex (adrenal adenoma)
• SECONDARY disease caused by hyperfunction of the anterior pituitary ACTH-secreting cells
• TERTIARY disease caused by hypothalamic dysfunction or injury
• EXOGENOUS STEROID use is the most common cause of Cushing syndrome in the United States
Hypercortisolism: Etiology and Pathogenesis
Causes of
Cushing’s SyndromeACTH
Most common cause
Cushing’s Syndrome
Redistribution of adipose:Truncal obesity, moon face, buffalo humpProtein wasting: limb musclesLoss of collagen: thin skin, striae, bruising
Cushing Syndrome: Clinical Manifestations
BUFFALO HUMP
STRIAE
MOON FACE
Clinical manifestations:
• Round face with flushed cheeks, “moon face”
• Weight gain with excess total body fat, particularly in the abdomen
• Cervical fat pad, capillary friability, thin skin with formation of purple striae and ecchymosis over the abdomen, arms and thighs
• Decreased muscle mass, muscle weakness
• Glucose intolerance, hyperglycemia• Hypertension
• Demineralization of bone (osteoporosis)
• Increased androgen production causing excessive hair production, acne, menstrual irregularities
• Emotional changes
Cushing Syndrome: Clinical Manifestations
Characteristic physical features of individuals with Cushing syndrome include:
A. weight loss and muscle wasting.B. truncal obesity and thin skin.C. pallor and swollen tongue.D. depigmented skin and eyelid lag.
Cushingism - Diagnosis
ACTH measurement Primary = low ACTHSecondary = high ACTH
Urinary free cortisol levels
Dexamethasone suppression test
Treatment is based on etiology
• Exogenous dose reduction
• Pituitary adenomas are treated surgically with transsphenoidal hypophysectomy, laser ablation, or radiation
• Adrenal tumor is treated with unilateral adrenalectomy
• Chemotherapeutic agents block cortisol production
Cushing Syndrome: Treatment
• Primary (Conn syndrome)—usually due to aldosterone-secreting tumors
• Secondary—typically associated with poor kidney perfusion that stimulates the renin-angiotensin-aldosterone cascade (heart failure, reduced kidney perfusion, liver cirrhosis)
Hyperaldosteronism:
• Aldosterone facilitates salt and water retention by the kidney with resultant potassium excretion
• Typically low potassium level
• Treatment includes spironolactone to increase sodium excretion and potassium retention
• Sodium restriction and potassium replacement may also be necessary
Hyperaldosteronism:
Adrenal Medulla Disorders
PheochromocytomaEtiology and Pathogenesis
Adrenal medulla hyperfunction• Caused by tumors derived from the chromaffin cells
of the adrenal medulla– Pheochromocytomas
• Secrete catecholamines on a continuous or episodic basis
Pheochromocytoma: Clinical Manifestations
• Diagnosed with abdominal CT/MRI
• Treatment includes sympathetic blocking medications to manage blood pressure and surgical removal of the tumor
• If surgery is contraindicated, medication to block catecholamine production is possible but surgery is the only curative therapy
Pheochromocytoma: Diagnosis and Treatment
Parathyroid Gland Disorders
What does PTH do?• Increases serum calcium & decrease serum phosphate1. Increase bone reabsorption of calcium2. Increase kidney reabsorption of calcium3. Decrease kidney reabsorption of phosphate4. Increase Vitamin D production in kidney
Parathyroid Gland
Parathyroid glands located at the upper and lower poles of the thyroid
Parathyroid Gland
Regulation of Calcium level
Regulation of Calcium level
osteoclasts
osteoblasts
Regulation of Blood Calcium
PTH• Serum calcium levels provide the
feedback to regulate parathyroid hormone (PTH) secretion
• Decrease in calcium causes PTH release
• Elevated calcium levels lead to suppression of PTH secretion
• PTH acts on bones, intestine, and renal tubules to increase calcium levels
• In bone, PTH increases osteoclastic activity
• PTH increases renal calcium reabsorption
Calcitonin • Calcitonin produced by thyroid
parafollicular cells also influences the processing of calcium by bone cells
• Calcitonin controls calcium content of blood by increasing bone formation by osteoblasts and inhibiting bone breakdown by osteoclasts
• Calcitonin decreases blood calcium levels and promotes conservation of hard bone matrix
Hyperparathyroidism: PTH, Ca+2, Phosphorous
(1) Primary hyperparathyroidism: • PTH, Ca+2, Phosphorous• Causes demineralization, extensive resorption• Hypercalcemia mostly affect the nervous system and kidney
(2) Secondary hyperparathyroidism: secondary to conditions that cause chronic hypercalcemia of nonparathyroid cause: major causes:
• Vitamin D-metabolite deficiencies• High phosphorus load
Parathyroid Disorders
Stones, Bones, Groans, Moans
• Kidney stones• Bone-related
complications• Abdominal groans• Psychic moans
Etiology: Genetic origin, Parathyroid adenoma, Hyperplasia of
parathyroid glands
Clinical manifestations• Kidney stones
• Bone demineralization (osteoporosis)
• Polyuria and dehydration
• Anorexia, nausea, vomiting, constipation
• Bradycardia, heart block, and cardiac arrest
Hyperparathyroidism
Treatment• Surgical removal of parathyroid gland
• Medical management includes hydration and ambulation to
maintain bone density
• For hypercalcemic crisis, rapid volume expansion with 0.9%
NS to treat dehydration and improve glomerular filtration
rate; diuretics to increase calcium excretion by the kidneys
Hyperparathyroidism
A problem associated with chronic hyperparathyroidism is:
A. seizure disorder.B. vitamin D malabsorption.C. hyponatremia.D. osteoporosis and pathologic fractures.
Alterations of Parathyroid Function:HYPOPARATHYROIDISM
– Abnormally low PTH levels
– Usually caused by parathyroid damage in thyroid surgery
Hypoparathyroidism: PTH, Ca+2, Phosphorous
(1) Primary hypoparathyroidism:
a) Idiopathic hypoparathyroidism * hormone-deficient hypoparathyroidism * PTH
b) Pseudohypoparathyroidism * hormone-sufficient, receptor-deficient hypoparathyroidism * PTH
(2) Secondary hypoparathyroidism: result from other disorders.
Parathyroid Disorders
Etiology• Parathyroid or thyroid surgery or surgery in the area of these
glands; may be temporary or permanent
• Permanent hypothyroidism can develop after thyroidectomy due to damage to parathyroid gland blood supply, postsurgical swelling, or fibrosis
• Congenital lack of parathyroid tissue and idiopathic hypoparathyroidism are causes of hypoparathyroidism in children and infants
• Autoimmune processes may target and damage the parathyroid glands
HYPOPARATHYROIDISM
What happens to serum calcium?Causes lowered threshold for nerve and muscle excitation
Clinical manifestations
• Circumoral numbness, paresthesias of the distal extremities, muscle cramps, fatigue, hyperirritability, anxiety, depression, ECG changes, increases in intracranial pressure
• Severe symptoms include carpopedal spasm, laryngospasm, and seizures
Treatment
• Acute hypocalcemic crisis (tetany, laryngospasm, and convulsions)—parenteral calcium administration and calcitriol, an activated form of vitamin D
• Long-term treatment: oral calcium supplement with vitamin D
Hypoparathyroidism
Antidiuretic Hormone
(ADH) Disorders
• ADH (vasopressin) secreted by the posterior pituitary gland in response to changes in blood osmolality
• ADH acts directly on the renal collecting ducts and distal tubules, increasing membrane permeability to and reabsorption of water
Antidiuretic Hormone
The single most important effect of antidiuretic hormone is to conserve body water by reducing the loss of water in urine
• Etiology and pathogenesis
– Disorder of INSUFFICIENT ADH activity resulting in excessive loss of water in urine
– DAMAGE to ADH-producing cells in the hypothalamus can result from:
• Traumatic brain injury• Intracranial tumors• Neurosurgical procedures
– Some pharmacologic agents can lead to abnormalities in ADH secretion
DIABETES INSIPIDUS: Antidiuretic Hormone Disorders:
• Central diabetes insipidus is due to the inability to produce and release ADH from the pituitary gland
• Nephrogenic diabetes insipidus results from the INABILITY of the kidneys to respond to ADH due to chronic renal disease, serum electrolyte abnormalities, or drugs
DIABETES INSIPIDUS: Antidiuretic Hormone Disorders
Syndrome of Inappropriate Antidiuretic
Hormone (SIADH)
Etiology
• EXCESSIVE ADH from ectopic production due to several types of tumors, notably primary lung malignancies
• Pulmonary tuberculosis
• Drug-induced ADH secretion can occur
SIADH: Antidiuretic Hormone Disorders
SIADH: Antidiuretic Hormone Disorders
REMEMBERWhat does Aldosterone do?
Clinical Manifestations
Diabetes Insipidus
• Polyuria, polydipsia
• Low urine specific gravity
• Hypernatremia due to water
deficit
• Dry mucous membranes, poor
skin turgor, decreased saliva
and sweat production
• Disorientation, lethargy,
seizures
SIADH
• Hyponatremia
• High urine osmolality
• Low serum osmolality
• Cell swelling
• Weakness, muscle cramps,
postural BP changes, poor skin
turgor, fatigue, anorexia, lethargy
• Confusion, seizures, coma
Treatment
Diabetes Insipidus
• Daily replacement of ADH
with desmopressin (DDAVP)
• Free access to fluids
• Home testing of urine
specific gravity
SIADH
• Free water restriction
• If severe symptoms, IV
administration of saline with
diuretics is used
• Hyponatremia should be
corrected slowly to avoid rapid
changes in brain cell volume
The most common cause of elevated levels of antidiuretic hormone (ADH) secretion is:
A. autoimmune disease.B. cancer.C. pregnancy.D. heart failure.
A 54-year-old patient with pulmonary tuberculosis (lung infection) is evaluated for syndrome of inappropriate ADH secretion (SIADH). Which of the following electrolyte imbalances would be expected in this patient?
A. HyponatremiaB. HyperkalemiaC. HypernatremiaD. Hypokalemia