PostMT Diuretics Flashcards
What is reacsorbed in PCT?
65% of Na, K, water
85% NaHCO3
100% of glucose and amino acids
What is reabsorbed in thick ascending LoH?
Impermeable to water.
25% of filtered Na reabsorbed
What establishes the cortex and medulla concentration gradient?
The Na/K/2Cl cotransporter in the thick ascending limb.
What drives Mg and Ca paracellular reabsorption?
The diffusion of K back into the lumen due to the incrased intracellular concentration gradient that creates an ELECTROPOSITIVE status in the lumen.
What % of Na is reabsorbed in DCT?
10%
What is Ca reabsorption regulated by in the DCT?
PTH
What is Ca reabsorption regulated by in the thick ascending limb?
electropositive gradient produced by K
Where does K balance and seretion primarily occur?
CCT
What are Aldosterone’s action?
Physiological results?
Na reabsorption
H+ expelled
K+ expelled
Results in increased water retention»_space; increased blood volume»_space; increased BP
What regulates ADH levels?
What does alcohol do?
serum osmolarity and volume
Alcohol decreases ADH release and increases urine production.
What two drug classes decrease body pH?
CAi’s (decrease bicarb formation in cytosol of PCT cells = decrased bicarb into interstitum»_space; less to body)
K-sparing (block Na channels, so Na cannot leave lumen = lumen remains more electropositive)
What two diuretic classes increase NaCl urinary content the most?
Loops and even greater, Loops + thiazides
Loops = block Na/K/2Cl
Thiazides = block Na/Ca cotransporter
What diuretic class increases urinary NaHCO3 most? What has no effect on NaHCO3 urinary levels?
CAi’s
Loops
What increases urinary K most?
Loops + thiazides
CAi
acetazolamide
CAi location of action and MOA
PCT
abolition of NaHCO3 reabsorption
Urinary and body result of CAi
DECREASED body pH (due to less bicarb reabsorbed).
INCREASED urinary pH (due to more NaHCO3).
Bicarb-esis, natriuresis, diuresis
How fast to CAi’s work?
Efficacy short or long course of admin?
Apparent within 30 min.
Significant loss of efficacy after several days of use.
CAi toxicity
- Metabolic acidosis.
- Ca2+ stones due to pH alkalinization (decreased calcium salt solubility)
Paresthesia, sulfonamide hypersensitivity
Cirrhosis is a contraindication for use of what diuretic? Why?
CAi use.
1. alkalinization of urine results in hyperammonemia and hepatic encephalipathy
What three things are contraindications of CAi’s?
Cirrhosis, severe COPD, hyperchloremic acidosis
Clinical indications of CAi’s?
What’s it rarely used for?
glaucoma,
urinary alkalinization or metabolic alkalosis
ACUTE MOUNTAIN SICKNESS
Rarely used as antiHTN.
Loop Diuretics
Names
Best used for what?
furosemide and ethacrynic acid
Most efficacious diuretic/volume depletion class.
Metabolism of CAi’s
excreted unchanged - no hepatic metabolism
Loop half life is correlated with what? Why?
Correlated with kidney function because it works on luminal side of tubule at Na/K/2Cl cotransport.
Co-administration of NSAIDS with a Loop (esp in a person with cirrhosis or nephritic syndrome) could result in what?
Reduction of loop secretion due to competition for weak acid secretion.
NSAIDs interfere because they reduce PG synthesis.
What do Loops cause?
uresis of Mg, Ca, Na, K, and water
Synthesis of PGs
Increasein renal blood flow to vascular beds
Weak inhibitors of CAi’s
Loop toxicity
hyponatremia (hepatic enceph in liver diseased patients)
hypokalemia, Mg, uricemia
ototoxicity (associated with renal dysfunction)
hyperuricemia