2 - Electrolytes and Fluids Flashcards
What factors regulate total body sodium?
Aldosterone
ANP
What factor alters [Na+]?
ADH
What is the difference between total body sodium and sodium concentration?
Total body sodium means that there is an increased amount of sodium located in the body. Usually this means there is also an increase in the amount of water in the body, so the sodium concentration does not change.
Sodium concentration refers to the ratio of sodium to water.
Aldosterone regulates the total number of sodium cells. ADH causes serum concentration by decreasing the amount of water, thereby increasing the Na concentration.
What regulates total body potassium?
Aldosterone
Intrinsic renal mechanisms
What regulates [K]?
Insulin
Epinephrine
What regulates total body Ca?
Vit D and PTH
What regulates [Ca]?
Vit D and PTH
How are Mag and Phos regulated?
Both total body and serum concentrations are regulated by intrinsic renal methods
with minimal input from PTH
the blood–brain barrier is poorly permeable to _______ but freely permeable to _______
Sodium
Water
How is serum osmolality determined?
2 x serum sodium + serum glucose + serum urea
A patient has a normal [Na] but an elevated serum osmolality. What is a likely explanation?
Increased glucose or BUN
What is the name of the vasopressin mediated water channel in the distal tubule?
Aquaporin 2
What can result from increasing serum Na too quickly?
Central Pontine Myelinolysis
How quickly should serum sodium be increased?
< 12 mEq/L/day
Carcinoid Syndrome
When a carcinoid tumore metastasizes to the liver and secretes its hormone into the portal vein and general circulation
What is the most common hormone carcinoids secrete?
Serotonin
Clinical manifestations of carcinoid syndrome
Flushing
Intestinal Motility (diarrhea)
R sided heart issues (TRegurg, pulm stenosis)
What are the components of TBW (Total Body Water)?
ICV (40% of total body weight)
ECV (20% total body weight)
What are the components of ECV (extracellular volume)?
Plasma (3L, 1/5 of of ECV)
Remainder is IFV (interstitial fluid volume)
Red cell volume contributes to ICV or ECV?
ICV!
Why is the brain so sensitive to changes in sodium?
The blood brain barrier is completely impermeable to sodium, so sodium levels directly influence fluid movement in and out of the cerebral circulation
Compare and contrast the effects of hypertonic saline and mannitol
Both cause a decrease in brain water
3% saline causes increased intravascular volume
mannitol causes diuresis, leading to decreased intravascular volume
Is mild hypovolemia associated with metabolic alkalosis or acidosis?
What about severe hypovolemia
Mild: alkalosis
Severe: Acidosis
How is sodium plasma concentration effected by glucose levels?
Glucose holds water within the extracellular space, cause dilutional hyponatremia