10 - Clinical Overview of Hypothalamus and Pituitary Disorders Flashcards
Describe the relationship of the hypothalamus and pituitary
The hypothalamus is a branch and the pituitary is fruit hanging off
Describe the role of the hypothalamus
- Controls output of the anterior pituitary by secreting “RELEASING HORMONES” which signal the release of hormones from the anterior pituitary
- Also control the output of the posterior pituitary by DIRECT nerve stimulation
What are the 6 hormones released from the anterior pituitary?
- Prolactin
- Growth hormone (GH)
- Thyroid stimulating hormone (TSH)
- Follicle stimulating hormone (FSH)
- Adrenocorticotropic hormone (ACTH)
- Luteinizing hormone (LH)
What are the 2 hormones that are released from the posterior pituitary?
- Antidiuretic hormone (ADH) or arginine vasopressin (AVP)
- Oxytocin
How do you access the pituitary gland surgically?
Through the nose - transsphenoidal surgery
What is important to remember about testing hormone levels for diagnosing disorders?
Can be different throughout the day
Example is Cushing’s Syndrome: increased midnight cortisol compared to normal people but apparently normal in the mornings
What does a deficiency of growth hormone in childhood cause?
Dwarfism
- Short stature, micropenis, increased fat, high-pitched voice
- Treat with GH replacement therapy with recombinant GH
What does a hypersecretion of growth hormone in youth lead to?
- Giantism in children or adolescents
- Very rare
What does hypersecretion of growth hormone in adults lead to?
Acromegaly
- Increased height, hand and foot sizes
- Soft tissue swelling
- Generalized visceromegaly—heart, tongue
- Upper airway obstruction
- Diabetes mellitus in 25%
- Increased risk of colon polyps and cancer
When are GH levels the highest throughout the day?
Just before the onset of sleep
When are prolactin levels highest thorughout the day?
During REM sleep (4-6 am)
What causes hyperprolactinemia?
Most common benign neoplasm—50% of all functioning (secreting) pituitary tumors
What is the female presentation of hyperprolactinemia?
- Amenorrhea
- Galactorrhea
- Infertility
- Mild hirsutism
What is the male presentation of hyperprolactinemia?
- Diminished libido or visual loss from optic nerve compression, headaches, gynecomastia, impotence
- Males usually have larger tumors
How do you treat hyperprolactinemia?
- Dopamine agonists
- Surgery
- Radiotherapy for aggressive tumors
What is the function of adrenocorticotropin hormone (ACTH)?
Stimulates the adrenal gland to produce corticosteroids and androgens
It peaks around 6 am and is lowest at midnight
What occurs in an ACTH deficiency?
Primary adrenal insufficiency or Addison’s disease
- Fatigue
- Weakness
- Anorexia
- Nausea
- Vomiting
- Weight loss
- Low BP
- Hypoglycermia
- Depression
Treat with a glucocorticoid like hydrocortisone or prednisone
What occurs in an ACTH hypersecretion?
Cushing’s syndrome
- Most cases are iatrogenic because if you take too many steroids it causes hypersecretion of ACTH
What are the sypmtoms of Cushing’s disease?
- Thin, brittle skin
- Central obesity with moon facies, buffalo hump (dowagers hump)
- Hypertension, purple striae and easy bruising
- Glucose intolerance or diabetes mellitus
- Acne, hirsutism, leukocytosis, lymphopenia, eosinopenia
What are the consequences of Cushing’s disease?
Increased morbidity and mortality of 30-50% at five years—related to high incidence of cardiovascular complications, such as hypertension, and diabetes in up to 50% of cases, which are exacerbated by obesity.
How do you treat Cushing’s syndrome?
Surgery followed by cortisol replacement
What regulating hormone controls both FSH and LH secretion?
GnRH - Gonadotropin releasing hormone
What occurs with a FSH/LH deficiency in women?
Women: menstrual irregularities, infertility, decreased vaginal secretions, decreased libido and breast atrophy, osteoporosis
What occurs with a FSH/LH deficiency in men?
Males: decreased libido and potency, decreased muscle mass with weakness, reduced beard and body hair growth, soft testes and osteoporosis
How do you treat FSH/LH deficiencies?
Females
- Replace estrogen and progesterone, use gonadotropins for ovulation
Males
- Testosterone replacement and hCG to restore fertility
What occurs in FSH/LH hypersecretion?
Gonadotropin-producing tumors usually only secrete a small amount of excess FSH/LH
The tumor itself could cause problems though…
- Compress pituitary stalk leading to less LH and hypogonadism
- Compression of optic chiasm leading to visual problems
How do you treat FSH/LH hypersection?
If small, just monitor
If large, surgery and radiation
What does a TSH deficiency lead to?
- Fatigue
- Dry skin
- Cold
- Hair loss
- Weight gain with poor appetite
- Puffy face
- Hands and feet (myxedema)
Treat with daily levothyroxine
What does a TSH hypersecretion lead to?
- Heat intolerance
- Palpitations
- Weight loss with increased appetite
- Goiter
- Periorbital edema and proptosis (exophthalmia)
Treat with surgery followed by somatostatin analogue
What is Graves?
Autoimmune hyperthyroidism
Treat with anti-thyroid drugs
Now onto posterior pituitary problems…
Remember ADH and oxytocin are the two hormones secreted from the posterior pituitary
What is the function of ADH?
- Reduces water excretion by increasing concentration of urine
- Secretion is regulated by the “effective” osmotic pressure of body fluids - osmoreceptors
What happens in the case of an ADH deficiency?
Diabetes insipidus
- Abnormally large volumes of dilute urine
- Idiopathic or vascular and many other causes
- Urinary frequency, enuresis and/or nocturia, thirst and polydipsia
Treat with synthetic ADH
What occurs with ADH hypersecretion?
SIADH = syndrome of inappropriate anti diuretic hormone
- Decreased volumes of highly concetrated urine
- Hyponatremia and water retetnion
What are the consequences of acute SIADH?
If acute, water intoxication; headache, confusion, anorexia, nausea, vomiting, coma, convulsions, death
How do you treat SIADH?
Acute: Restrict fluids, give hypertonic (3%) saline
Chronic: give a diuretic
What is pituitary apoplexy?
Bleeding into or impaired blood supply of the pituitary gland at the base of the brain
What causes pituitary apoplexy?
Intrapituitary hemorrhagic vascular events
This can occur
- Spontaneously in preexisting adenoma
- Postpartum (Sheehan’s syndrome)
- In association with diabetes, hypertension, sickle cell anemia or acute shock
How severe is pituitary apoplexy?
Endocrine emergency
What are the symptoms of pituitary apoplexy?
- severe headache
- bilateral visual changes
- in severe cases, cardiovascular collapse, loss of consciousness
What can pituitary apoplexy lead to?
May result in severe hypoglycemia, hypotension, CNS hemorrhage and death
How do you treat pituitary apoplexy?
- Surgery (if loss of vision or consciousness has occurred
- If still awake, high dose of glucocorticoids
Case 2
- 56 year old man
- 50 lb weight gain
- Forehead growth
- Excessive sweating
- Feeling very hot
- High blood pressure
- Enlarged tongue
Diagnosis: acromegaly
Treatment: growth hormone receptor antagonists, surgery, somatostatin analogues, radiation (or any combo)
Case 3
- 24 year old female
- Weakness
- 35 lb weight loss
- Low blood pressure
- Lightheaded and dizzy
- High serum calcium, potassium and urea
- Low serum sodium
Diagnosis: Addison’s disease
Treatment: Glucocorticoid
Case 4
- 30 year old woman
- Dealing with infertility for 2 years
- Amenorrhea 10 months ago
- Breast secretions, decreased libido
Diagnosis: Pregnancy
Test for serum prolactin
Case 5
- 54 year old man
- Polyuria
- Polydypsia
- Head trauma 5 months ago
- Diluted urine
Diagnosis: deficiency of antidiuretic hormone (ADH) or vasopressin
