Renal Path Flashcards
Failure of alpha intercalated cells to secrete acid can cause which type of RTA?
Type I
Type II RTA is usually associated w/ what syndrome?
fanconi syndrome
The main cause of Type II RTA is what?
impaired ability of PT to reabsorb bicarbonate
All RTAs will cause normal anion gap metabolic acidosis. All RTAs will cause hypokalemia except for which one?
Type IV (causes hyperkalemia)
What is the main cause of Type IV RTA?
hypoaldosteronism
Dehydration (inadequate fluid intake) can cause which electrolyte disturbance?
hypernatremia
What is the main cause of an increased anion gap metabolic acidosis?
ketoacidosis and ingestion of fixed acids (such as ethylene glycol, aspirin, & methanol)
Decreased HCO3- reabsorption cause normal anion gap metabolic acidosis. Why?
The net loss of negative charge in the plasma will compensated by reabsorption of more Cl- (another measured anion)
How does the body initially compensate for metabolic acidosis?
It will decreases pCO2 via expelling more CO2 through hyperventilation
In cases of chronic metabolic acidosis, how will the body compensate?
Production of Ammonia causes proton trapping in tubular lumen of CD via exchanging protons instead of potassium to make ammonium (NH4+)
How can chronic cases of metabolic alkalosis lead to hypokalemia?
intracellular inorganic phosphate will exchange extracellular protons for intracellular K+, thus trapping K+ in the tubular lumen and increase K+ secretion
Hypoventilation can compensate for acute metabolic alkalosis. How does hypoventilation decrease plasma pH?
If respiration is decreased, more acidic CO2 will remain in the bloodstream thus decreasing plasma pH
How can recurrent episodes of emesis lead to metabolic alkalosis?
Excessive loss of gastric protons decreases pancreatic secretion of bicarbonate
How does aldosterone affect plasma pH?
Increases pH due b/c aldosterone promotes H+ excretion in CD
How can diarrhea lead to metabolic acidosis?
diarrhea decreases bicarbonate reabsorption in the colon thus decreasing serum bicarbonate
In the context of plasma volume, what is the physiological consequence of enhanced response to ADH and how can diuretics counteract it?
Blood becomes overdiluted leading to edema; when blood becomes overdiluted, BP will be dangerously elevated; diuretics can counteract this by driving more fluid into intravascular compartments to be excreted through the kidneys
How does SIADH cause hyponatremia?
ADH’s overall effect is to increases plasma volume and elevate BP; it does this by increasing water reabsorption which decreases plasma osmolarity
How can ACE inhibitors cause hyperkalemia?
inhibition of RAAS will decrease K+ secretion in DCT & CD
What conditions can cause pseudohyperkalemia?
Tumor lysis syndrome & rhabdomyolysis
What is the pathogenesis of Bartter Syndrome?
mutations of genes that codes for NKCC channels
Based on your understanding of how ADH & aldosterone influence electrolyte balance through their actions on ROMK & NKCC channels, what can you predict will be the physiologic consequences of Bartter Syndrome?
ADH & aldosterone work together to elevate BP; if these hormones cannot act on receptors that drive this process, hypotension will result; impaired ability of ADH to act on NKCC channels will decrease Ca & Mg reabsorption leading to hypercalciuria, hypocalcemia, & hypomagnesemia; additionally, insensitivity to ADH will impair the body’s ability to retain water leading to polyuria & polydipsia
What is the pathogenesis of Gitelman syndrome?
mutations of the gene that encodes for NCC channels
What are the diagnostic hallmarks of Gitelman syndrome?
hypercalciuria, alkalosis, low serum Cl & Mg
How does renal artery stenosis impair kidney function?
decreased RBF into the kidney thus decreasing GFR
What are the main causes of Hydronephrosis?
outlet obstruction due to a kidney tumor, enlarged prostate, or kidney stones; posterior urethral valves
How does hydronephrosis affect glomerular hydrostatic pressure?
it increases it
How can CHF lead to acute kidney injury?
decreased blood flow activates baroreceptor complex in cardiac atria which stimulates ADH release in posterior pituitary; this can cause fluid volume overload in the kidneys
How can acidemia cause hypercalcemia?
in an acidic pH environment, protons will outcompete Ca ions for binding to albumin leaving ionized Ca in the plasma
How can hypercalcemia cause arrhythmias?
hypercalcemia decreases excitability via stabalizing the action potential gradient (making it more neutral); Intracellular Ca is higher relative to the extracellular concentration
How can hypocalcemia increases risk of tetany & clonus?
it increase neuron excitability due to lowered threshold
what conditions can lead to an increased BUN?
decreased GFR; high protein diet; CHF; hypovolemia
How does Cushing’s syndrome affect kidney function?
cortisol increases expression of NHE; too much cortisol can cause to much reabsorption of bicarbonate
what conditions can lead to a decrease in BUN?
liver failure/disease; SIADH
What effect does increased intracranial pressure have on serum glucose levels?
it decreases serum glucose concentration
What is the pathogenesis of Alport syndrome & what are common associated symptoms?
x-linked mutation of type IV collagen; associated with hearing & vision loss; renal disease; hematuria, proteinuria (nephritic syndrome); progresses to ESRD
urothelium is what type of epithelium?
transitional epithelium
What kind of metabolic disturbances can result in hypermagnesiumenima?
ESRD; inhibition of K+ & Ca2+ channels; hypoparathyroidism
ANGII does what to the efferent arteriole to increase GFR?
vasoconstricts it
Why would you want to decrease GFR in a pt. that has hypoalbuminemia?
If the pt. is losing albumin to urine, it would make sense decrease GFR, b/c this will cause more fluid to leave through the efferent arteriole and bypass the glomerulus
What is a physiological consequence of prolonged use of loop diuretics?
Loop diuretics block transporting channels in the TAL which is the primary site for Magnesium reabsorption; so chronic use would lead to hypomagnesemia
How would you expect chronic kidney disease to impact serum sodium levels?
Reduced kidney function will decrease sensitivity to ADH & aldosterone the two main hormones that regulate renal sodium reabsorption; this will decrease sodium reabsorption leading to hyponatremia
How would you expect CKD to impact serum potassium levels?
reduced kidney function will decreases sensitivity to ADH & aldosterone, the two main regulators of potassium secretion leading to hyperkalemia
How would you expect CKD to impact serum calcium & phosphate levels?
There are two main mechanisms that regulate renal calcium & phosphate reabsorption: PTH & Vit. D; when kidney function is reduced, it is not producing as much Vit. D. leading to hypocalcemia and is not as sensitive to PTH which will cause hyperphosphatemia
how would you expect CKD to impact serum magnesium levels?
Mg2+ reabsorption is coupled to Ca2+ & K+ transportation in NKCC2 & ROMK channels in the TAL;
