Hypo and Hyper Na+/K+ Flashcards
What is the most common form of RTA?
RTA Type 4
lack of aldosterone or failure to respond to it
What is the role of the NK2Cl transporter in the TAL?
helps give rise to dilute tubular fluid and hypertonic renal medullary interstitium in combo w/ water impermeability and direction of flow outside TAL
What transporter is target of loop diuretics?
NK2CL transporter in TAL
What is the role of insulin?
hormone primarily responsible for cell uptake of K+
can cause HYPOk w/ normal acid-base balance
What occurs in SIADH?
causes euvolemic hyponatremia
What is the role of the V2 receptor in the collecting duct?
mediates response to ADH
leads to insertion of AQ2 water channels in luminal membrane for water reabsorption
What electrolyte disturbance can be caused by vomiting episodes?
hypoNa, hypoK, hypovolemia
metabolic alkalosis w/ renal retention of K & Na
What is sensed by special sensors in brain?
body osmolality
What is DDVAP (desmopressin)?
V2 agonist used to tx central DI
What is tolvaptan?
V2 receptor antagonist that can be used orally to pts w/ persistent hyponatremia despite use of initial therapies
What is ADH?
hormone released by PP whose receptor-mediated water-retaining effects are blocked by vaptans
What is the effect of alcohol?
consumption decreases ADH secretion
What is given to pt w/ hypokalemia and acidosis?
potassium salt (formed w/ acetate)
What is an invasive method to tx life-threatening hyperkalemia?
dialysis
When would you consider RTA in a pt?
acidemia w/ normal AG and serum CR level and NO diarrhea
What can cause pseudohyponatremia?
large volume of LIPID in plasma
What occurs if give pt digoxin with a loop diuretic?
toxicity of digoxin is increased by K+ loss induced by loop diuretic
What is a toxicity of loop diuretic?
ototoxicity
What is mannitol?
osmotic diuretic used to eliminate excess intracellular volume
What type of solution is used to tx acute severe hyponatremia?
hypertonic solution (3% NaCl, causes cells to shrink)
What can cause pseudohyperkalemia?
cell lysis in a collected blood sample
What is the fxn of osmotic diuretics?
cause polyuria (excrete excess glucose in urine)
What acts @ proximal tubule?
osmotic diuretics and carbonic anhydrase inhibitors
What is affected @ prox tubule?
where can increase or decrease fraction of filtered load that is reabsorbed
determines Na+ excretion
What is route for Mg2+ and Ca2+ reabsorption?
both paracellular @ TAL; Ca2+ paracellular @ prox tubules
What is a potential AE of spironolactone used by males?
gynecomastia
What can influence stone formation?
increase risk w/ more Ca2+ in urinary pelvis by loop diuretics
decrease risk w/ less Ca2+ in urinary pelvis by thiazide diuretics
What is caused by both loop and thiazide diuretics?
hyperuricemia
can increase risk of gout
What is 1st line tx for symptomatic hospitalized pt w/ hyponatremia?
If fails, what is next used?
fluid restriction
if fails to tx, indication for vaptans
What is CI for loop diuretics and not good time for thiazides?
pregnancy
What is MOA and indication for acetazolamide?
inhibitor of carbonic anhydrase (causes Na+ HCO3 diuresis w/ hyperchloremic acidosis)
used for urinary alkalization to hasten elimination of weak acid toxins, tx of metabolic alkalosis, acute mtn sickness and glaucoma
What is MOA and indication for conivaptan?
V2 receptor antagonist to cause H2O excretion w/o solute excretion
used to tx euvolemic and hypervolemic hyponatremic if unresponsive to other tx
What are PE findings of hypovolemia?
thirst, tenting of skin, sunken eyes and oliguria
stronger stimulus for ADH release
What can cause hyperkalemia?
tissue necrosis
What is a common cause of hypervolemic hyponatremia?
heart failure
What portion of nephron increase K+ reabsorption when plasma levels are low?
distal nephron (esp collecting duct)
What are sxs of hyper aldsteronism?
hypervolemic hypernatremia
hypokalemia w/ metabolic alkalosis
urinary Cl- loss even w/ low plasma levels and HTN
What is an AE assoc w/ admin of tolvaptan for >30 days?
hepatotoxicity
What class of diuretics act in collecting duct?
K+ sparing diuretics
block Na+/K+ exchange to counterbalance AE of loop and thiazide diuretics
What is spironolactone?
aldosterone antagonist
effects in principal cells of collecting duct to act as K+ sparing diuretic
What is MOA of triamterene?
blocks ENaC channels in principal cells of collecting tubule and duct
What is role of aldosterone?
hormone whose levels decrease in response to dietary Na+ load to help facilitate its renal elimination
What are some causes of hyperkalemia?
anything that interferes w/ normal renin secretion or angiotensin II generation or the actions of angio II/aldosterone
What type of solution is used to tx hypernatremia?
hypotonic (0.45% NaCl causes cells to swell)
What dz causes hyperkalemia despite nl GFR?
Addison dz
What organ does not have space for cells to swell?
BRAIN (in setting of hyponatremia)
lack of space leads to sxs of encephalopathy and possible uncal herniation +/-death
How do loop and thiazide diuretics cause hyponatremia?
excess loss of Na+ and H2O
What is a potential AE of spironolactone in females?
hirsutism
How is free water clearance related to urine osm?
free H2O clear is zero when urine is isotonic
+ when urine is dilute
- when urinary solute returned to body
What is Fanconi syndrome?
cause of type 2 RTA due to impaired ability to reabsorb filtered HCO3 in prox tubule
What is a consequence of tx hyponatremia too rapidly?
osmotic demyelination
What ion exchanges w/ cellular K+ during acid base maintenance?
HYDROGEN
reason acidosis can cause hyperkalemia
What is administered to raise threshold potential when people present w/ hyperkalemia?
calcium
What is significant about intercalated cells?
change phenotype and assoc w/ maintenance of acid-base balance
What cells do thiazide diuretics target?
intercalated cells in distal nephron
What is equivalent to infusing volume of distilled water?
administer 5% solution of dextrose
Why is tolvaptan still used?
slow progression of APKD
What is the aldosterone antagonist w/ greater selectivity?
eplerenone
Describe GFR requirements for diuretics
thiazide do NOT work if GFR<30 ml/min
loop diuretics work if GFR<30 ml/min
can be cause of hyperkalemia if GFR<5
What remains unchanged when excreting max dilute or max conc urine?
elimination of solute
What is the most common electrolyte abnormality seen in clinical practice?
HYPOnatremia
Na+ conc <135
What is the effect of licorice?
dose dependently potentiates aldosterone effects and increases systolic blood pressure
What changes occurs with step change in daily sodium intake?
increase in body weight
What cells are primary target of K+ sparing diuretics?
principal cells in collecting duct
What receptors sense body Na+ content via measure effective blood volume?
stretch receptors
What is the role of TRPV5 receptor?
Ca2+ reabsorption in DCT
major site of regulation w/ calcitriol (to increase synthesis) and PTH (regulate conductance)
What increases K+ excretion from distal nephron?
increased tubular fluid flow rate
What are K+ losing diuretics?
thiazides, loops, carbonic anhydrase inhibitors, osmotic diuretics
What occurs with abuse of laxatives?
extra renal K+ losses leading to hypokalemia that can occur +/- concurrent metabolic acidosis
What occurs in severe hypokalemia, DI and vaptan use?
polyuria
What is glomerulotubular balance?
forces acting across proximal tubular epithelium that result in proportional amounts of isotonic fluid reabsorption from prox tubule
What loop diuretic can be used in pts w/ sulfa allergy?
ethacrynic acid
What defines hypokalemia and outcome?
plasma K+ <3.5
hyperpolarizes most cell membranes
can be caused by K+ losing diuretics
Hypovolume v hypervolume
too little or too much sodium in body
What is a cause of hyperosmolar hyponatremia?
hyperglycemia
What prevents plasma potassium toxicity from dietary intake?
rapid redistribution of K+ into cells
What is role of TPRV6 channel?
Mg2+ reabsorption in DCT which somewhat blocked in TAL by loop diuretics
will downregulate in presence of thiazides leading to more profound Mg2+ loss in urine
What is an important indication for loop diuretics?
ASCITES that occurs in liver dz due to impaired synthesis of plasma proteins and increased portal venous pressure
What is indication for salt tablets?
tx for hypovolemic hyponatremia
What volume is expanded by infusion of 0.9% NaCl solution?
extracellular volume
What drives water movement across cell membranes?
osmotic pressure
What promotes excretion of urine and can cause hypovolemic hyponatremia?
diuretic
What sx is among neuromuscular manifestations of hypokalemia?
constipation
What type of paralysis is seen in worsening hyperkalemia?
FLACCID paralysis
twitching/weakness and numbness/prickling sensation
What occurs when K+ (and Cl-) are lost in urine due to diuretics?
metabolic alkalosis due to cells donating K+ while taking up H+ to maintain plasma K+ levels near normal
Where do loop diuretics act?
high ceiling effects exerted in TAL
What becomes prominent in severe hypokalemia?
U waves
What acids have less effect on plasma K+?
organic acids
Hyponatremia v hypernatremia
too much or too little WATER diluting body Na+ content
What can be hidden source of excessive K+ intake?
antibiotics
What is a healthy way to transiently raise extracell K+ levels?
exercise
What is most common cause of nephrogenic DI?
lithium to tx bipolar disorder
How to tx nephrogenic DI due to lithium toxicity?
amiloride
What is MOA of thiazide and indication?
medium Na+ losing ability b/c block of transporter in DCT
tx nephrogenic DI
What is furosemide?
LOOP diuretic
What is caused by lack of ADH secretion or failure of kidneys to respond to ADH?
diabetes insipidus
can lead to euvolemic hypernatremia
What change in HR is consequence of hyperkalemia?
BRADYCARDIA
b/c hyperkalemia increases K+ conductance in SA node tissue to cause membrane hyperpolarization
higher risk of arrhythmia
What is impaired in Bartter syndrome, use of loop diuretics, and hypokalemia?
concentrating ability of kidneys
results in polyuria, nocturia
What type of metabolic alkalosis is seen w/ thiazide and loop diuretics?
HYPOchloremic secondary to K+ loss
What is problematic with diuretics?
nonadherence due to urgent need to urinate
What interval is widened by hyperkalemia?
QRS interval
What is administered as the coma cocktail?
GLUCOSE in pts presenting w/ hyperkalemia
How does urinary output of Na+ change as BP increases?
increased sodium urinary output
What is nephrogenic diabetes insipidus?
form of DI when kidney fails to respond to ADH
What is osm of urine when use max dose of furosemide?
ISOTONIC urine (irrespective of plasma ADH levels)
What is autoregulation?
myogenic mechanism and tubuloglomerular feedback that maintains RBF and GFR at range of MAP
What is hypomagnesemia?
plasma level <1.7
often seen w/ hypoK and Ca2+
clinical sxs of muscle weakness, tremors, tetany, seizures, paresthesias, torsades de pointes
What is role of magnesium?
crucial cofactor in many biological processes
normal level regulation via reabsorb through TRPM6 channels in DCT
What extrinsic factors modify intrinsic renal relationship btwn arterial pressure and sodium excretion?
Ang II
ANP
SNS activity
What is a sign of neglect in nursing homes?
hypovolemic hypernatremia
What is MOA of amiloride?
diuretic that blocks epithelial Na channels in principal cells of collecting ducts
rapid onset of action
When is not a good time to take loop or thiazide diuretic?
bedtime
What characterizes fluid removal response to diuretics?
rapid and massive
What signifies that too much sodium is in 1 compartment?
EDEMA
indication for loop diuretic
What promotes free water clearance?
aquaretic
What is RTA type 1?
RTA w/ hypokalemia due autoimmunity (causes fibrosis w/ impaired fxn in cortical collecting duct)
What channels are blocked by amiloride and triamterene in collecting duct cells?
ENaC
What is determined by extracellular K+ levels?
resting membrane potential
What defines tx of chronic hyponatremia or hypernatremia?
SLOW rate of correction
What drugs interfere w/ renin secretion and ability of diuretics to cause diuresis?
NSAIDs
What co-transporter in DCT further dilutes tubular fluid?
NaCl
target of thiazide diuretics
What is typical route for KCl administration for pt w/ hypokalemia?
ORAL
