Acute Kidney Failure

Question 1

AKF: define:

Answer 1

1. Kidney can’t maintain homeostasis, leading to nitrogenous waste buildup

NOT SAME AS renal insufficiency where kidney function is deranged, but can still support LIFE!!

Question 2

AKI defined as; define anuria, oliguria, polyuria

Answer 2

occurring over hrs/days; lab definition is increase in baseline creatinine by 50% or decrease in clearance by 50%; often a deterioration of renal function which requires dialysis;

anuria: less than 100 mls/24 hr OR no urine output
oliguria: 2.5 L/24hr

Question 3

Causes of AKI:

Answer 3

1. pre-renal (inadequate perfusion with absolute and relative hypovolemia, reduced CO, renovascular occlusion: check volume status)
2. Renal (AKI despite perfusion and excretion with ATN, AIN, atheroemboli: check UA, full blood count, autoimmune screen)
3. Post-renal (blocked outflow with pelvi-calyceal, ureteric, vesicoureteric junction, bladder neck: check bladder, catheter, US)

Question 4

For ATN, causes?

Answer 4

1. ischemic
2. nephrotoxic: endogenous toxins (heme pigments like myoglobin and hemoglobin; myeloma light chains) vs exogenous (aminoglycosides, amphotericin B, radiocontrast agents, heavy metals with cis-platinum, mercury, poisons like ethylene glycol) HARP

Question 5

For AIN, causes? Clinically?

Answer 5

1. allergic IN (drugs)
2. infections (bacterial, viral)
3. sarcoidosis; SIA!!!
   fever, rash, arthralgias, eosinophilia, UA (microscopic hematuria, sterile pyuria, eosinophiluria) FU RAE

Question 6

Contrast-induced AKI: prev? risk factors?

Answer 6

Less than 1% in patients with normal renal function;

1. renal insufficiency
2. DM
3. multiple myeloma
4. high osmolar contrast media (try low-osmolar)
5. contrast medium volume (try and minimize)

The RM DOVe

Question 7

clinical characteristics of contrast-induced AKI and pre-procedure prophylaxis?

Answer 7

24-48 hrs after exposure, lasts 5-7 days, non-oliguric (majority), dialysis rarely needed, urinary sediment (variable), low fractional excretion of Na;
IV fluid, mucomyst (N-acetylcysteine), bicarb, maybe fenoldopam but the go-to is IV fluid!!

Question 8

Glomerulonephritis is characterized by

Answer 8

inflamm and damage of the glomeruli; allows leak of protein w/w/o blood in urine

Question 9

Proliferative vs. non-prolif glomerulonephritis examples:

Answer 9

1. Membranoproliferative, post-infectious, IgA nephropathy, rapidly progressive glomerulonephritis (Goodpasture vs. vasculitic disorders like Wegeners and microscopic polyangiitis)
2. Membranous, minimal change, FSGS

Question 10

AKI post-renal causes:

Answer 10

1. Intra-renal obstruction: acute uric acid nephropathy, drugs (acyclovir)
2. extra-renal obstruction (renal pelvis or ureter like stones, clots, papillary necrosis, tumors), bladder (BPH), urethra (stricture)

Question 11

Bland urinary sediment seen in

Answer 11

pre-renal azotemia and urinary outlet obstruction

Question 12

RBC casts or dysmorphic RBCs seen in

Answer 12

acute glomerulonephritis and small vessel vasculitis

Question 13

WBC’s and WBC casts seen in

Answer 13

AIN, acute pyelonephritis

Question 14

ATN would show _____ in urinary sediment:

Answer 14

1. renal tubular epithelial cells,
2. RTE cell casts
3. pigmented granular (muddy brown) casts

Question 15

FeNa < 1% in; 1-2% in; >2% in

Answer 15

1. prerenal
2. ATN (unusual)
3. glomerular or vascular injury;
4. prerenal
5. ATN sometimes
6. AIN: higher FeNa b/c of tubular damage;
7. ATN

Question 16

AKI signs and symps:

Answer 16

weight gain, peripheral edema, HTN; hyperkalemia, N/V, pulmonary edema, ascites, asterixis, encephalopathy

Question 17

Lab findings in AKI:

Answer 17

1. rising creatinine and urea
2. rising K
3. decreasing Hb
4. Acidosis
5. Hyponatremia
6. Hypocalcemia

Question 18

Indications for acute dialysis:

Answer 18

1. Acidosis (metabolic)
2. electrolytes (hyperkalemia)
3. ingestion of drugs/ischemia
4. overload (fluid)
5. uremia