disorders of water balance Flashcards
hypernatremia
hyper-osmolality indicating a water deficit (high serum sodium concentration)
hyponatremia
hypoosmolality indicating a water excess (low serum concentration)
water in body provide information on sodium content?
nope
what refers to sodium content
volume
fluid in the vascular space that perfuse tissue
effective circulating volume
conditions of inadequate perfusion
ineffective circulating volume
conditions of ineffective circulating volume
- heart failure
- cirrhosis
- nephrotic syndrome
reflects total number of particles in solution
osmolality
reflects total number of osmotically active particles in solution
osmotic pressure
true or false:
osmotically active solute diffuse freely
nope
sensor for osmolality
osmoreceptors in the anterior hypothalamus
mediators for regulating osmolality
- ADH/vasopressin
2. thirst
vasopressin regulates
vascular smooth muscle tone
sensor for vasopressin
baroreceptors in the carotid sinus
effect of vasopressin and why
binds to V1aR to help limit blood loss by vasocontrisciton
at high concentration urine is ADH high or low
high
hyponatremia is definec by
a fall in Posm <280
hyponatremia can occur from
insufficient water loss either from ADH disorder or excessive water intake
tea and toast diet
low dietary solute intake with water intake
SIADH
normal volume status (euvolemia) but apropiadamente ADH presence
manifestations of chronic or actue hyponatremia:
seizure, coma, respiratory distress, cerebral herniation
acute
V2 antagonist
blocks tubule effect of ADH
treatment of chronic hyponatremia
correct underlying cause and restore balance by decreasing water and increasing solute
in settings of normal volume status, concentrated urine is inappropriate and identifies a diluting defect
SIADH
hypersomolality can be due to
- diabetes insipidus
- loop diuretics
- sodium/solute gain
hypernatremia usually does not occur due to
thrist activation
disbetes insipidus in the absence of ADH
central
diabetes insipidus in the setting of resistance of ADH
nephrogenic
no or poor response to ADH
nephrogenic
what doe lithium might cause
nephrogenic diabetes insipidus
hyperosmolality will often be hypovolemic/euvolemic/hypervolemic
euvolemic
which diuretic might block Li+ effect
amiloride
managment of DI
- access to water
- ADH if central
- limit distal solute delivery
Plasma osmolality can often be estimated
by doubling the serum Na concentration
incorrect when non-electrolyte osmoles are present in high concentration
ADH is release from the posterior pituitary under circumstances of (2)
1) hyperosmolality sensed by the osmoreceptors of the hypothalamus,
2) significant ineffective circulating volume sensed by the carotid and aortic bodies.
The kidney handles water by (5)
1) filtration,
2) bulk reabsorption in the PCT,
3) creation of a hypertonic medulla by the counter-current multiplier in the LOH,
4) creation of a dilute filtrate in the DCT, and
5) variable permeability of the CT according to the presence or absence of ADH.
The serum Na concentration should be raised by no more than 0.5 mEq/L/hr to prevent
central pontine myelinolysis
Treatment of hypoosmolality requires inducing a negative water balance with ______ water intake and ________ water excretion.
Increased water excretion can be achieved by suppressing _____(if possible), blocking ______ (with drugs called Vaptans), or providing extra ______ to facilitate additional water excretion (at the same urine osmolality).
Treatment of hypoosmolality requires inducing a negative water balance with decreased water intake and increased water excretion.
Increased water excretion can be achieved by suppressing ADH (if possible), blocking ADH receptors (with drugs called Vaptans), or providing extra osms to facilitate additional water excretion (at the same urine osmolality).
The serum Na concentration should be lowered by no more than ____ mEq/L/hr to prevent brain swelling and herniation
0.5
Treatment of hyperosmolality requires ______
water administration.
