Syndrome Inappropriate Antidiuretic Hormone Secretion Flashcards
What syndrome is the opposite of DI?
Syndrome Inappropriate Antidiuretic Hormone (SIADH)
What is the key characteristic that defines SIADH?
Excessively high levels of ADH expression.
What does excessively high levels of ADH expression lead to?
Very high urine osmolarity (extremely concentrated/super yellow)
What are 4 secondary results of high ADH levels?
- Total body water increases
- The blood becomes hypo-osmolar
- Hyponatremia (plasma Na+ drops)
- Cells swell
If hyponatremia (low plasma Na+ levels) occurs, what are 6 symptoms that follow?
- Headaches
- Nausea
- Vomiting
- Behavioral changes
- Coma
- Seizures
What are the 4 causes of SIADH?
- Malignant tumors
- Cranial disorders
- Non-malignant pulmonary disorders
- Drugs
How do malignant tumors cause SIADH?
They can release ADH-like substances.
How do cranial disorders cause SIADH?
They can exorbitantly increase the normal expressions of ADH from the brain.
How do non-malignant pulmonary disorders cause SIADH?
Positive-pressure hyperventilation can cause excessive release of ADH
What 3 drugs can stimulate ADH release?
- Clofibrate
- Phenothiazines
- Carbamazepine
What drug can increase the sensitivity of the renal tubules to ADH?
Chlorpropamide
What drug can increase renal sensitivity to ADH and also cause stimulate ADH release from the brain?
Carbamazepine
ADH (anti-diuretic hormone) is also known as? (2)
- AVP (arginine vasopressin)
2. Vasopressin
How can you treat SIADH?
Fluid restriction in diet.
Infusion of hypertonic plasma Na+ ( >110mM) - must be gradual
Why must infusion of hypertonic plasma Na+ be gradual in treating SIADH?
Because rapid changes may cause rapid changes in the volume size of neuronal cells.
