The Posterior Pituitary Gland dysfunction Flashcards
ADH secretion is controlled by _____
1) hyperosmolar state via hypothalamic osmoreceptors
2) hypovolemic state via baroreceptors
what are the MOA’s for ADH
V1 – Vascular Vasoconstriction, Platelet aggregation
V2 - Antidiuretic effects in kidney: Adenylate cyclase activation -> movement of Aquaporin water channels to the cell membrane -> water reabsorption
What is the definition of SIADH
A syndrome of inappropriate AVP (ADH) release/action in the absence of physiologic osmotic or hypovolemic stimulus.
what is the Hallmark of SIADH
excretion of inappropriately concentrated urine in the setting of hypo-osmolality and hyponatremia.
_______ is one of the most frequent causes of hyponatremia, and occurs in an estimated:
15-22% of hospitalized patients
5-7% of ambulatory patients
SIADH
what are some drugs that can cause SIADH
Narcotics, Nicotine, Anti-psychotics, Carbamazepine, Vincristine
what is the criteria for SIADH diagnosis
Hyponatremia (Na+ <135 mmol/L) and hypotonic plasma (osmolality <275 mOsm/kg)
Inappropriate urine concentration (Urine Osm >100 mOSm/kg) with normal renal function
SIADH can present with ___
altered mental status, seizures
How to treat Mild-to-Moderate Hyponatremia (Na+ ~120-134 mmol/L)?
Water Restriction (500-1000L/24hrs)
V2 Receptor Antagonists (e.g., Tolvaptan, Conivaptan, $$$)
Salt tablets, Lasix
How do you treat Severe Hyponatremia (usually Na+ <120 mmol/L)
Hypertonic (3%) Saline-if patient is symptomatic (delirium/seizure/coma)
what are ways to Reduce Risk of Hyponatremia Complications
Limit Correction of Chronic Hyponatremia:
< 12 mmol in the first 24 hrs.
Slower correction with other risk factors associated with osmotic demyelination syndrome
Hypokalemia, alcoholism, poor nutritional status.
NO LIMITATIONS with acute onset hyponatremia (e.g., <48 hr onset, marathon runners)
What is the definition of diabetes insipidis?
DI is a syndrome of hypotonic polyuria as a result of either:
Inadequate ADH secretion
Inadequate renal response to ADH
what is the Hallmark of DI
Voluminous (Urine output > 40ml/kg/d) dilute urine
what are the 2 main cause of DI?
Central Diabetes Insipidus
Nephrogenic Diabetes Insipidus
What is the Tx for central DI
Anti-Diuretic Hormone Replacements:
First Line-dDAVP (nasal, oral or parenteral routes of administration)
Longer half-life than ADH
No Vasopressor Effect
Second-Line-ADH (IV, SQ or IM routes of administration
