TBL - AKI

Question 1

What are complications of acute kidney injury (AKI)?

Answer 1

Volume overload (plasma)

Hyperkalemia

Metabolic acidosis

Hyperphosphatemia

Question 2

What are categories of AKI?

Answer 2

Prerenal azotemia = accumulation of nitrogen

functional AKI

Intrinsic AKI

Postrenal AKI

Question 3

What is the mechanism for prerenal azotemia?

Answer 3

Dec. in ECV = dec. renal perfusion = dec. RPF + glomerular capillary pressure = dec. GFR

Decreasing ECV means there will also be a decreased renal perfusion, resulting in increased sympathetic stimulation to kidney and increased renin. With less blood coming to kidney there, there will be dec. AA stretch (which will directly increase renin via renal BRR). Symp stimulation will also directly inc. renin via beta adrenergic receptors

Question 4

What are other mechanisms associated with prerenal azotemia?

Answer 4

Inc. renin = inc. AngII = inc. Aldo = inc. CNT/CD ENaC activity = inc. Na/H2O reabsorption

Inc. Na/H2O reabsorption = inc. urea reabsorption = inc. BUN

Inc. Na/H2O reabsorption = dec. excretion and dec. fractional excretion of sodium

Dec. renal perfusion = dec. GFR = inc. plasma creatinine

Dec. renal perfusion = inc. ADH = inc. urine osmolality and dec. renal flow

Question 5

What are key findings associated with prerenal azotemia?

Answer 5

High BUN/Plasma creatinine ratio

Usually greater than 20:1

Question 6

What is the mechanisms for functional AKI?

Answer 6

Dec. hydraulic pressure in GC from drug effects on AA or EA = dec. GFR

Question 7

What is AKI?

Answer 7

Acute decrease in GFR which results in accumulation of metabolic waste products and decreased urinary excretion

Question 8

What are AA constrictors?

Answer 8

NSAIDs

Dec. vasodilatory PGs = dec. RPF and GC hydraulic pressure = dec. GFR

Question 9

What are EA dilators?

Answer 9

ACEIs
ARBs
(Since AngII constricts EA more than AA)

Net effect is decrease in GC hydraulic pressure and GFR

Question 10

What is a common cause of intrinsic AKI?

Answer 10

Drug-induced

Radiocontrast media nephropathy - where contrast media becomes damaging to kidney by causing decrease in GFR

Question 11

What are recommendations for patients receiving radiocontrast?

Answer 11

D/c NSAIDs, ARBs, and ACEIs before contrast

D/c drugs cleared by kidneys where accumulation can lead to toxicity
Example: metformin

Question 12

What is the mechanism of postrenal AKI?

Answer 12

Obstruction to urine flow
(Inc. in hydraulic pressure @BS = dec. GFR)

Examples:
BPH, nephrothiasis

Question 13

What are top causes of chronic kidney disease (CKD)?

Answer 13

2 = HTN

#1 = DM
(High blood sugar means more filtered glucose - if SGLT gets worked harder then sodium reabsorption increases = dec. salt delivery to macula densa = MD sends signals to dilate AA, inc. pressure in GC)

Question 14

What are complications of CKD?

Answer 14

Anemia
(Dec. [hemoglobin] or dec. in Hct)

Renal osteodystrophy (ROD): bone problems due to

• low calcitriol
• high PTH
• dec. GFR = inc. plasma phosphate = inc. FGF23 = dec. calcitriol = inc. PTH

Question 15

What treatments are available for CKD?

Answer 15

Epoetin-alfa
(Inc. Hct and [Hb])

Vitamin D analogs
Vit. Effects help dec. PTH

Calcimimetics

Phosphate binders

Anti-hypertensives

Question 16

What is a vitamin D analog?

Answer 16

Doxercalciferol

Question 17

What is a calcimimetic?

Answer 17

Cinalcalcet

Activates CaSR on PTH glands to dec. PTH

Question 18

What is a phosphate binder?

Answer 18

Sevelamer

Dec. GI phosphate absorption = dec. plasma phosphate