Pathophysiology of Water Handling Flashcards
What causes Nephrogenic Diabetes Insipidus?
ADH resistance
What are the 3 main categories of hyponatremia?
- hypertonic
- isotonic
- hypotonic
What causes euvolemia?
- SIADH
- 1° Polydipsia
- Hypothyroidism
- Adrenal Insufficiency
What causes Isotonic Hyponatremia?
- hyperlipidemia
- hyperproteinemia (multiple myeloma)
- ***this is a lab artifact
What is SIADH?
syndrome of inappropriate ADH secretion; hypoosmolality and less than maximally dilute urine
What causes inappropriate ADH secretion?
- Hypothyroidism
- drugs (nicotine, isoproterenol, SSRIs, morphine, barbs, aspirin)
- adrenal insufficiency
- 1a polydispsia
How do you test for central diabetes insipidus?
kidneys should respond to exogenous AVP with a rise in Uosm of 100 mOsm/kg above the levels achieved following water deprivation
Sodium is transported on the Na+-K+-2Cl- cotransporter in the ______ and by the thiazide-sensitive NaCl cotransporter in the ______.
thick ascending limb; distal convoluted tubule
High serum uric acid levels suggest volume ______.
depletion
If the UNa is less than 20 in hypervolemia, the cause is ______.
- CHF
- cirrhosis
- nephrotic syndromes
_____ occur with severe or acute hyponatremia.
Seizures
Low serum uric acid levels suggest ______.
euvolemia
What is the equation for Serum osmolality (Sosm)?
2 X [Na] + [BUN/2.8] + [Glucose/18]
For each increase in serum glucose of ____mg/dL, serum sodium will fall by about ____mEq/L.
100; 1.6
______ is transported on the Na+-K+-2Cl- cotransporter in the thick ascending limb and by the thiazide-sensitive NaCl cotransporter in the distal convoluted tubule.
Sodium
If the UNa is less than 20 in hypovolemia, the cause is ______.
extrarenal losses
What causes Central Diabetes Insipidus?
ADH deficiency
What is the tx for minor hyponatremia?
- dietary water restriction
- Na/Cl +/- furosemide
What are the 3 categories of SIADH?
- CA
- pulmonary disease
- CNS disorders
Drugs such as ______ antagonize the end-organ effect of AVP.
lithium or demeclocycline
Water deficits should be restored slowly in order to avoid ______.
sudden shifts in brain cell water
What is Congenital nephrogenic DI?
a rare sex-linked (male) disorder in which cyclic AMP is not generated in response to AVP
What causes decreased total body Na?
- GI loss (diarrhea)
- skin loss (burns)
- diuretic use without sufficient water intake
- mechanical ventilation
What is the normal serum osmolality range?
280-295 mOsm/kg
Hypernatremia occurs only when (1) ______ or (2)_____.
- ADH is decreased
- ineffective daily water intake (less than that required to compensate for normal insensible, gastrointestinal, and renal losses)
Sodium is transported on the ______ in the thick ascending limb and by the thiazide-sensitive _____ in the distal convoluted tubule.
Na+-K+-2Cl- cotransporter; NaCl cotransporter
Low serum _____ levels suggest euvolemia.
uric acid
For each increase in serum _____ of 100 mg/dL, serum _____ will fall by about 1.6mEq/L.
glucose; sodium
If the UNa is greater than 20 in hypervolemia, the cause is ______.
- ARF
- CKD
If the UNa is greater than 20 in hypovolemia, the cause is ______.
renal losses
Drugs such as lithium or demeclocycline antagonize the end-organ effect of _____.
AVP
What 2nd messenger does ADH use?
adenylate cyclase (which generates cyclic AMP)
High serum ____ levels suggest volume depletion.
uric acid
Hyponatremia is most commonly caused by _____.
a relative excess of water
What causes Hypotonic Hyponatremia?
the nonosmotic release of ADH that prevents maximal urinary dilution –> need to check the volume status next
What causes Hypertonic Hyponatremia?
- hyperglycemia
- mannitol or glycerol administration
What causes increased total body Na?
hypertonic fluid administration
______ is a rare sex-linked (male) disorder in which cyclic AMP is not generated in response to AVP.
Congenital nephrogenic DI
