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)
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?
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
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