Hyper/Hypo BS Flashcards
What is the main extracellular cation?
Sodium
The “-volemias” refer to what is being perceived on _________ ______
physical exam
In order for this to happen, there must be an increase in both water AND sodium
Hypervolemic Hypernatremia
What is the most common form of hypervolemia hypernatremia?
Iatrogenic – from the administration of sodium bicarbonate
What is another cause of hypervolemia hypernatremia?
Primary aldosteronism
What does primary aldosteronism cause hypervolemia hypernatremia?
Increased aldosterone causes increased sodium reabsorption
sodium reabsorption causes water to passively follow it, which is why hyperaldosteronism can cause hypervolemia
To be hypovolemic and hypernatremic, there must be more _________ loss than _______ loss if one is losing both
more WATER loss, than sodium loss
Losses of water and/or sodium can be classified as renal loses or extrarenal losses – what are examples of both?
renal losses: renal disease or diuretics
extrarenal losses: sweat, stool
If the clinical history and physical exam cannot distinguish between renal and extrarenal losses, what are you going to do!?
Look at their urine – urine electrolytes will tell you the difference!
If the water/sodium loss is occurring extrarenally, will sodium concentration in the urine increase or decrease? why?
Decrease! the kidneys are still working here! so they will hold on to that sodium making the sodium concentration less in the urine!
What if the cause of hypovolemic hypernatremia is renal? what will the sodium urine concentration look like?
HIGH! kidneys suck – can’t hold on to sodium, out it goes.
If the sodium concentration is greater than ____ meq/L the sodium losses are renal. If they are less than ______ meq/L the sodium losses are extrarenal.
20!
Although patients may appear euvolemic, they are technically losing or gaining some water?
Losing
What are the two causes of euvolemic hypernatremia?
Diabetes insipidus and hypodipsia
Whats the difference between central diabetes insipidus and nephrogenic diabetes insipidus?
Central is a problem in the posterior pituitary – you aren’t making ADH
Nephrogenic is when there is no response to ADH
What are two cases when the body inappropriately increases the intravascular volume resulting in hypervolemia, hyponatremia?
Heart failure and cirrhosis
Heart failure and cirrhosis cause hyper or hypovolemia? and hyper or hyponatremia?
Hypervolemia, hyponatremia
To be hypovolemic and hyponatremic, there must be both water and sodium loss, but relatively more ______ loss than ______ loss.
sodium, water
If we can’t tell on physical exam if someone is hypovolemic and hyponatremic, what are we going to do?
Look at the urine
If the urine sodium concentration is greater than 20meq/L, the kidneys must be losing the sodium.
If the urine sodium is less than 20meq/L, the the sodium must be lost in some other way such as sweat, stool, or edema
Adrenal insufficiency, hypoparathyroidism, primary polydipsia, and SIADH can all cause?
Euvolemic hyponatremia
If patients with euvolemic hyponatremia have kidneys that are functioning normally, they will be urinating large or small amounts?
Large! trying to maintain clinical euvolemia
Osmolality refers to the amount of _____ dissolved per kilogram ______
solute, solvent
An increase in glucose, lipids, proteins, or urea will raise or lower serum osmolality? why?
Raise! because they will pull water into the intravascular space to re-equilibrate things.
This would lead to an increased water to sodium ratio and thus hyponatremia.
In uncontrolled diabetes mellitus, the glucose concentration can raise/lower the serum glucose levels?
Raise the serum glucose levels!
Water can be drawn into the intravascular space in an attempt to maintain fluid balance. This can result in hyponatremia and even hyperosmolar coma.
The hypervolemic states are secondary to?
Fluid overload
- Can be an IV solution-generated hypernatremic one
OR
- An internally-generated HYPOnatremic one (CFH, cirrhosis)
In hypernatremia there is either net ______ of salt or net ______ of water.
Gain, loss
In hyponatremia, there is either net _____ of salt or net ______ of water.
Loss, gain
What is the main intracellular cation?
Potassium
Serum potassium concentration can increase secondary to what three basic mechanisms?
- Increased intake
- Decreased urinary excretion
- Increased movement of potassium from cells into the bloodstream
Is it easy to eat too much potassium result in increased serum potassium?
No – thats a lot of potassium.
Are you more likely to get hyperkalemia from eating too much or from getting an infusion of potassium at an inappropriately high dose?
Definitely the infusion
Decreased urinary excretion is a mechanism for increased serum potassium – what are the three ways that this can happen?
- Renal failure
- Decrease in flow rate
- Hypoaldosteronism
How would renal failure lead to hyperkalemia?
The kidneys have difficulty filtering and excreting potassium
Why would a decreased flow rate in the nephron cause hyperkalemia?
A decreased flow rate in the distal nephron can perceive high concentration of potassium, which can inhibit further secretion of potassium in the nephron.
Why would hypoaldosteronism lead to hyperkalemia?
Aldosterone is the hormone responsible for potassium excretion – low levels will result in low excretion
If there is too much acid in the blood (aka too much hydrogen), how will this affect potassium concentrations?
Hydrogen will move from the blood into the cell, and potassium will move out (as they have equal charges) – resulting in hyperkalemia
What if blood is alkalotic? what will happen to potassium serum levels then?
If there is not enough hydrogen in the blood, cells will release hydrogen into blood in exchange for potassium, which will cause HYPOkalemia.
Insulin will cause potassium to enter or exit the cell?
Enter!
If someone has insulin deficiency, what effect will this have on serum potassium levels?
Serum potassium levels will be high! If the insulin is deficient, potassium isn’t going to move into the cell.
Hypokalemia can be caused by what three mechanisms?
- Decreased intake
- Increased loss (renal or GI)
- Movement of potassium from the blood into cells
Is hypokalemia from decrease intake common?
No – very rare. More of a contributing factor
What effect will an increased distal flow rate in the nephron have on potassium levels?
Increased distal flow rate will wash away potassium, making the lumen of the nephron appear to be lacking in potassium, which in turn causes potassium secretion.
Aka, hypokalemia.
Vomiting and diarrhea will cause hyper or hypokalemia?
Hypokalemia
Hyperkalemia – what will you see on EKG?
Peaked t-waves
Aldosterone causes reabsorption of ______ and secretion of _______
sodium, potassium
