Electrolytes Flashcards
What happens when there’s a 1-2% increase in Na or a 10% decrease in blood volume?
osmoreceptors in the hypothalamus sense the change–> vasopressin secreted from posterior pituitary–> enhances H2O resorption in renal CDs
Na is a major determinant of intra or extracellular osmolality?
extra
incr in BP–> sensed by ______–> impulses to the ____ to inhibit ____ release and decrease ___ resorption in the distal nephron
incr in BP–> sensed by arterial and atrial baroreceptors–> impulses to the hypothalamus to inhibit vasopressin release and decrease Na resorption in the distal nephron
What happens when there is a decrease in BP to stimulate an increase in resorbed water in the kidneys?
decr in BP–> sensed by juxtaglomerular cells–> activate RAAS by secreting renin–> renin cleaves angiotensinogen to angiotensin I–> angiotensin I converted to angiotensinogen II by ACE–> angiotensinogen triggers release of aldosterone from the adrenals, secretion of vasopressin, and stimulates thirst
What are the actions of angiotensinogen II?
triggers release of aldosterone from the adrenals, secretion of vasopressin, and stimulates thirst
T or F: All hyperNa animals are hyperosmolar
T
What is the normal ECF osmolality?
300 mOsm/kg
What are effective osmoles?
osmoles that contribute to tonicity
What are examples of effective osmoles?
glucose, EG, propylene glycol
T or F: BUN is a strong effective osmole
F- BUN is an osmole but doesn’t cornice to tonicity b/c can freely diffuse across membranes
What is an example of a hypertonic rumens where BUN actually contributes to hypertonicity and is an effective osmole?
urea toxicosis
T or F: Hypoosmolar pts always have hypoNa.
T
T or F: HypoNa pts always are hypoosmolar.
F (if concurrent hyperglycemia)
What are 3 scenarios where you may have hyponatremia without a decrease in osmolality?
- Pseudohyponatremia when indirect potentiometry and flame photometry are used and Na is measured in plasma and not just plasma H2O
- Marked hyperlipemia or hyperproteinemia displaces the plasma H2O
- Translocational hypoNa: concurrent hyperosmolality from some other substance (glucose, EG, mannitol, etc)
HypoNa in a normovol patient indicates…
increased total body Na
HypoNa in a dehydrated patient indicates…
Na and H2O are being lost together but Na loss is > H20; indicates severe total body Na deficit
HypoNa in a pt with ascites or edema indicates…
H2O is accumulating faster than Na can increase; tuna is normal to increased
HyperNa in a dehydrated pt indicates…
H2O loss w/o Na loss, tbNa is normal and ECF volume is decreased
HyperNa in a normovol pt indicates…
increase in tuna (usually excess salt w/o access to water)
What are 3 mechanisms of hypoNa?
- excess water diluting out Na
- endogenous shifts
- losing Na in excess of H2O
What are 3 causes of renal Na loss leading to hypovolemic hypoNa?
- proximal tubule dysfx–> less Na resorption
- Addisons
- osmotic diuresis (DM)
What are 3 main causes of non-renal Na loss leading to hypovolemic hypoNa?
- GI (diarrhea or vomiting)
- 3rd spacing (ruptured bladder, peritonitis, chylothorax)
- cutaneous (sweating in horses)
What are 4 causes of excessive water intake causing euvolemic hypoNa?
- PD
- SIADH
- Antidiuretics
- hypotonic fluid admin
What are 4 causes of volume overload leading to hypervolemic hypoNa?
- CHF
- Liver disease
- nephrotic syndrome
- advanced (oliguric/anuric) renal failure
What are 5 reasons for low Na:K?
- addisons
- renal/urinary tract disease
- GI dz/parasitism
- body cavity effusions
- repeated chylothorax drainage
Chloride is an anion or cation?
anion
Chloride is primarily in the ECF or ICF?
ECF
How can hyperCl be related to secretory acidoses?
when you lose bicarb, you retain Cl to stay electroneutral
What are 5 conditions that you might lose bicarb and have a resulting hyperCl?
- diarrhea
- saliva loss in cattle
- vomiting
- renal loss with proximal or distal tubular acidosis
- chronic respiratory alkalosis (there’s a decr in renal conservation of bicarb)
What can cause an artificial increase in chloride?
halides (bromide or iodide)
What is the corrected Cl formula?
Corr Cl= Normal Na/measured Na x measured Cl
K is primarily and intra or extracellular ion?
intra
Is K an anion or cation?
cation
Which species have normally high intracellular K?
Horses, pigs, primates
___-___% of K is excreted in the kidneys. Where is the rest excreted?
90-95%, 5-10% excreted in colon