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Describe pituitary change during pregnancy
- Estrogen causes an increase in size
- Hypertrophy and hyperplasia
Which park is must susceptible to trauma?
The stalk - may rupture
What is Sheehan's Syndrome?
- Circulatory collapse secondary to severe hemorrhage at parturition
- Reduction in blood supply causes pituitary necrosis
- Often, gland restored with time
How are breast cancers dangerous to the pituitary?
Often metastasize to pituitary - rapid growth under prolactin influence
Types of pituitary tumors
- Chromophobe tumors (most common)
- Acidophilic tumors
- Basophilic tumors (least common)
What is Multiple Endocrine Neoplasia?
Genetic disease where patients develop cancers in one or more hormone-producing organs
Signs/symptoms of pituitary tumors
- Loss of visual fields (upper temporal first)
- Excessive hormone secretion
- Loss of pituitary function
Identify disease states caused by excess of the hormone:
1. Growth Hormone
- 1. Acromegaly, gigantism
- 2. Cushing's disease
- 3. Galactorrhea - amenorrhea syndrome
Do pituitary tumors metastasize?
- Yes, rarely
- Pituitary carcinoas
Where does ADH act?
- Acts on distal tubule and collecting duct
- Increases permeability to water
How is ADH release regulated?
- Osmoreceptors in hypothalamus
- Volume receptors in left atrium
Describe transport and storage of oxytocin and ADH
- Transported down neurohypophyseal tract as inactive precursors
- Cleaved to generate ADH or oxytocin
- Stored in Herring bodies for release
How do neurotransmitters control ADH secretion?
- Norepinephrine - inhibits ADH release
- Acetylcholine - stimulates ADH release
Types of Diabetes Insipidus
- Neurohypophyseal DI
- Nephrogenic DI
- Phychogenic Polydipsia
Describe Neurohypophyseal DI
- Partial or complete lack of ADH secretion
- Hypovolemia, hyperosmolality, hypernatremia
- Treat with ADH therapy
Describe Nephrogenic DI
- Partial or complete lack of ADH action (renal disease)
- Caused by congenital ADH insensitivity or nephropathy
Describe Psychogenic Polydipsia
- Compulsive water drinking
- Caused by functional disturbance in thirst mechanism
- Causes washout effect - impairs short term ability of kidney to concentrate urine
Treatment for Diabetes Insipidus
- Neuro - give exogenous ADH or drugs which increase ADH effect
- Nephro - give Thiazides to reduce free water clearance