Acute Kidney Injury Pathophysiology - Zhang

What are the 3 categories of AKI?

prerenal, instrinsic, postrenal

What defines the pathophysiology of prerenal AKI?

renal blood HYPOperfusion

long answer: decreased renal blood perfusion (renal hypoperfusion) (no damage to the parenchymal/functional tissue of an organ, diff from the connective and supporting tissue)

What defines the pathophysiology of intrinsic/renal AKI?

ischemia or toxins

long answer: structural damage to kidney, most commonly tubule from ischemic or toxic insult (acute tubular necrosis, ATN)

What defines the pathophysiology of postrenal AKI?

obstruction of urine flow downstream from kidney

What are the causes of renal hypoperfusion with systemic arterial hypotension?

1. instrinsic volume depletion (ie. GI loss: V/D, diuretics…)

2. decreased effective circulating blood volume (ie. decreased cardiac output or systemic vasodilation/sepsis)

What are possible causes of prerenal AKI?

NSAIDs, ACEi, ARB, Cacineurin imhibitors

which renal hypoperfusion is most commonly associated with renal artery occlusion?

renal hypoperfustion WITHOUT systemic hypotension (aka. drug-induced)

Patients at risk for prerenal AKI are particularly susceptible to changes in the _____ and _____ arteriolar tone

afferent, efferent

What meds can cause drug-induced prerenal AKI?

ACE-i/ARB, NSAID

Most cases of intrinsic AKI can be ID’d with ________

tubular damage (acute tubular necrosis, ATN)

What are possible causes of intrinsic AKI?

ATN nephrotoxins (endogenous or exogenous toxins or contrast dye) and ischemia

The most common causes of postrenal AKI is what?

prostatic process/hypertrophy (hypertrophy/Benign prostatic hyperplasia, cancer, infection)

Which of the following is most likely the cause of intrinsic AKI?

1. hypovolemia (decreased in blood volume)

2. medications that induce acute tubular necrosis (ATN)

3. prostate hypertrophy

medications that induce acute tubular necrosis (ATN)

Which of the following is most likely the cause of prerenal AKI?

1. hypovolemia (decreased in blood volume)

2. medications that induce acute tubular necrosis (ATN)

3. prostate hypertrophy

hypovolemia (decreased in blood volume)

Which of the following is most likely the cause of postrenal AKI?

1. hypovolemia (decreased in blood volume)

2. medications that induce acute tubular necrosis (ATN)

3. prostate hypertrophy

prostate hypertrophy

In terms of the diagnosis of AKI, what indicates prerenal AKI?

urine Na < 20, specific gravity > 1.018

In terms of the diagnosis of AKI, what indicates intrinsic AKI?

urine Na > 40, specific gravity < 1.012

In terms of the diagnosis of AKI, what indicates postrenal AKI?

urine Na > 40, specific gravity variable

Which diuretic is most likely to cause allergic reaction to patients allergic to sulfa?

1. furosemide

2. mannitol

3. erythonic acid

furosemide

Prostate hypertrophy is a major cause for ______ AKI

postrenal

Which of the following is most likely a cause of intrinsic AKI?

1. hypovolemia (decreased blood volume)

2. medications that induce acute tubular necrosis (ATN)

3. prostate hypertrophy

medications that induce acute tubular necrosis (ATN)

Which of the following is most likely a cause of prerenal AKI?

1. hypovolemia (decreased blood volume)

2. medications that induce acute tubular necrosis (ATN)

3. prostate hypertrophy

hypovolemia (decreased blood volume)

Urine sodium (45mmol/L) and urine specific gravity (1.010) indicate the possibility of ______ AKI.

intrinsic

Urine sodium (17mmol/L) and urine specific gravity (1.022) indicate the possibility of ______ AKI.

prerenal

If prerenal AKI caused by hypovolemia is left untreated, _____ AKI may occur.

intrinsic

MOA of loop diuretics

inhibit NKCC2, induce expression of cyclooxygenase COX-2

Of the loop diuretics, which increases renal blood flow?

furosemide

Why is furosemide more commonly used compared to the other loop diuretics?

lower cost, PO and Parenteral, reasonably safe

What are the benefits of torsemide and bumetanide over furosemide?

more predictable oral bioavailability, higher potency

Please arrange the loop diuretics in terms of potency

Bumetanide > torsemide > furosemide

Please arrange the loop diuretics in terms of predictability in terms of oral bioavailability:

torsemide and bumetanide > furosemide

Which loop diuretic is recommended for patients with allergy to sulfonamides?

ethacrynic acid

What are the side effects of loop diuretics?

electrolyte imbalance, metabolic alkalosis, hyperuricemia, otoxicity, allergic/other reactions

Comparing loop vs thiazide, which causes hypo-/hyperkalemia?

both cause HYPOkalemia

Comparing loop vs thiazide, which causes hypo-/hypernatremia?

both cause less frequent hyponatremia

Comparing loop vs thiazide, which causes hypo-/hypercalcemia?

loop - HYPOcalcemia, thiazide - HYPERcalcemia

Comparing loop vs thiazide, which causes hypo-/hypermagnesemia?

both cause hypomagnesemia

Comparing loop vs thiazide, which causes H+ imbalance (metabolic acidosis or metabolic alkalosis)?

both cause metabolic alkalosis

Comparing loop vs thiazide, what is the only difference in electrolyte imbalance?

calcium