Transcript Acute Renal Failure - Catalyst

Molly Blackley Jackson, MD
Assistant Professor
Department of Medicine
University of Washington
Objectives
 Understand definition of AKI
 Think in an organized way about differential diagnosis
 Perform appropriate initial work-up
 Understand first steps in management
 Know when to consult nephrology
 Review common causes of AKI
Case 1
62 year old man with obesity, diabetes, hypertension, and
venous insufficiency presents to the ED with malaise and
nausea over last 24 hours. Creatinine at presentation is 2.8
(baseline 1.3).
Is this acute kidney injury?
Quick differential diagnosis? What is likely, what should we
“not miss”?
Initial approach: think buckets
prerenal (70-80%)
renal (10%)
vascular
glomerular
tubulointerstitial
postrenal (10%)
Pre-renal
 Volume depletion: poor po intake, vomiting, diarrhea,
diuretics, third-spacing
 Hypotension: sepsis, drugs, bleeding, liver disease
 Decreased cardiac output: CHF, acute MI
 Poor arterial perfusion: renal artery stenosis, embolism,
thrombosis
Often multifactorial, with meds exacerbating
Renal / Intrinsic
Vascular injury: Malignant hypertension, ANCA positive
granulomatosis with polyangitis (Wegener’s), PAN
Glomerular injury: Post-strep GN, lupus, RPGN, hepatitis-related,
IgA nephropathy
Interstitial: Acute Interstitial Nephritis (AIN)
Intra-tubule deposition/obstruction
Tubular injury: Acute Tubular Necrosis (ATN) often from prerenal
‘hit’, toxins (antibiotics, contrast, rhabdo)
Postrenal
Urethral stricture
Tumor (lymphoma, ovarian, prostate)
Neurologic (i.e. overflow incontinence)
BPH
Blocked urinary catheter
Nephrolithiasis (very unlikely unless bilaterally obstructive)
Case 1 – work-up
62yo man with DM2, obesity, diabetes, hypertension, and venous
insufficiency with malaise and nausea x 24h. Cr is 2.8 (baseline
1.3). What do you want to do first for diagnostic work-up?
A. Urine electrolytes
B. UA with microscopy
C. Physical exam with orthostatics
D. Renal ultrasound
E. All of the above
Initial diagnostic work-up
Physical exam!
Blood pressure
Estimate CVP by measurement of JVP
Orthostatics
Palpation of bladder for distention
Exam for pulmonary and/or peripheral edema
Signs of uremia (N/V, fatigue, mental status changes, asterixis,
pericardial rub)
Initial diagnostic work-up
Fractional Excretion of Sodium
Chem 7, ca/mag/phos
Urine lytes (Na, Cr)
CBC
UA with microcopy
Una x PCr
PNa x Ucr
Prerenal
Intrinsic
Postrenal
FENa UNa
< 1 % < 10
>2%
> 20
hard to interpret
Bladder scan +/- renal US
http://www.medcalc.com/fena.html
When is FeNa not reliable?
Case 1 - treatment
62yo man with mild CKD now with AKI admitted to wards with
dehydration, gastroenteritis. BP is 110/60 with HR 80 laying
down, 100/50 with HR 112 standing. Neck veins are flat. K is 5.0.
What do you want to do to manage his kidney injury?
A. 125cc / hr of D5NS with 20meq KCl
B. 1L normal saline IV x 1
C. 25g IV albumin (25%)
D. Place a Foley catheter
E. Ask nurse to call if urine output is less than 80 cc/hr
Management Principles
Remove toxins: “FTD” = first think drugs
Trial of fluids (unless volume overloaded)
Carefully manage volume (daily weights, strict I/Os, VS)
Avoid extra K (in IV fluids, diet)
Check post-void residual volume (PVR)
.. then repeat chem panel
Next steps
Proceed with diagnostic workup based on your weighted differential
diagnosis. This may include….
Spot protein to creatinine ratio
SPEP/UPEP
Urine eosinophils
ANA panel
C-ANCA
HIV
Hepatitis B/C
ASO titer
Renal biopsy?
When to consult nephrology
Dialysis is potentially needed
fluid overload, hyperkalemia, acidosis, uremia
Intrinsic renal disease (other than simple ATN)
especially if biopsy may be necessary
Diagnosis is uncertain despite your initial work-up
Case 2
55 yo man with DM2, presents with nausea, low UOP,
swelling x 2 days.
Baseline Cr=1.6, + proteinuria. On lisinopril and insulin.
Had cardiac catheterization five days ago.
BUN/Cr = 20/5.0, K=6.1, BP is 190/110. His JVP is 9 cm, he
has bibasilar crackles, and 1+ LE edema.
Case 2
FeNa = > 1
Una = 50 (high)
Case 2
What is the most likely cause of the ATN?
A. Cholesterol emboli
B. Volume depletion
C. Heart failure
D. Lisinopril
E. Contrast-induced kidney injury
Contrast-Induced Kidney Injury
 Highest risk in pts with DM2, advanced age, underlying
renal disease, hypovolemia
 Usually non-oliguric; creatinine rises over 2-7 days
 Think prevention: hold nsaids/diuretics….. Give pre-
hydration, consider n-acetylcystine (low harm, might help);
bicarbonate infusion benefit not clear
Cholesterol Crystal Embolism
Recovery is much slower (and often incomplete)
Clinical features:
 eosinophila
 eosinophiluria
 hypocomplimentemia
Look for showering of crystals in other distributions:
 orange blobs in the retinal arterioles (Hollenhorst plaques)
 abdominal pain (mesenteric ischemia?)
Case 3
26 year old woman with nausea, vomiting and
shortness of breath x 1 week. Started about 1
month ago with a sore throat, then she felt better
for a few weeks. Creatinine at presentation is 4.5.
Quick “weighted” differential?
Case 3 (cont.)
Urine Na = 30 (high)
FeNa 1.86
UA: + protein
Renal US normal
UA with microscopy
finds these casts:
Case 3 – work-up
What test would you like next, to help confirm
the likely diagnosis?
A. Anti-DNA level
B. Anti-GBM antibodies
C. ANCA panel
D. Streptozme
E. Hepatitis B / C panel
Acute glomerulonephritis
Postinfectious GN: Streptozyme (ASO plus four other
streptococcal antibodies)
Lupus nephritis (diffuse proliferative): elevated anti-DNA levels,
low complement (biopsy if active urine sediment or significant
proteinuria)
RPGN (crescents) (e.g.Goodpasture’s, immune complex, pauciimmune): anti-GBM antibodies, ANCA, biopsy
Membranoproliferative: check hep B, C; biopsy
Vasculitides (Wegener’s, Churg-Strauss, microscopic polyangitis)
Glomerulonephritis
Child / adolescent: Postinfectious GN, membranoproliferative
GN
Young to middle age: Postinfectious GN, lupus nephritis,
RPGN (crescents), IgA nephropathy,
membranoproliferative GN, fibrillary GN
Older than 40: RPGN, vasculitides , IgA, postinfectious GN
Post-streptococcal GN
Appears 7-21 days after pharyngeal or skin infection
(impetigo) with group A beta-hemolytic strep
Hematuria, hypertension, edema, pulmonary congestion
UA shows dysmorphic RBCs and RBC casts
Streptozyme test; 80-95% specific
5% will progress to RPGN; 70% recover
Case 3 - treatment
What is the best treatment approach for poststreptococcal GN?
A. Diuresis
B. Gentle fluids
C. Clindamycin
D. High-dose penicillin
E. Trimethoprim-Sulfa
Case 4
40 y.o. man with history of IV heroin use, chronic severe low
back pain. Admitted with fever, found to have right-sided
endocarditis, blood cultures + MSSA
Admission BUN 40, Cr 1.4 but then…
Cr 1.4  1.4  1.9  4.0
Outpt Meds: Methadone and ibuprofen
Inpt treatment: fluids, initially vancomycin, then transitioned to
nafcillin / gentamicin
Case 4
Una = 60
UA 2+ protein,
otherwise normal.
Urine microscopy:
Case 4
What put this patient at risk for acute ATN?
A. Advanced age
B. Volume depletion
C. Hypertension
D. Ibuprofen prior to admission
E. All of the above
ATN due to Aminoglycosides
 Related to trough levels of drug and duration; tissue half-life
>> serum half-life
 Co-factors: Age, renal disease, volume depletion,
hypertension and other toxic drugs (10-20% overall risk)
 Gradual onset, proteinuria, concentrating defects,
nonoliguria… usually reversible
Case 5
49 y.o. man with COPD, depression and hypertension who is
admitted with abd pain, nausea and found to have pancreatitis.
Outpt meds: metoprolol, ASA, amitriptyline, albuterol
Admission WBC 14, hct 29, BUN 28, Creatinine 1.8
Made NPO, started on hydromorphone PCA, ondansetron and
scopalmine patch for nausea.
Case 5
On hospital day 2, he looks (and feels) much better on your prerounds, but you are called by his nurse for low urine output
(only 80 cc overnight).
Blood pressure 170/90, HR 80. Normal orthostatics. Abdomen
soft, distended, but less pain. Normal cardiac and pulm exam.
Labs that morning notable for normalizing WBC (was elevated),
and improving creatinine (now 1.2), normal calcium.
Case 5
What is the most likely reason for low urine
output?
A. Volume depletion
B. Volume overload
C. Urinary obstruction
D. Pancreatic pseudocyst
E. Acute interstitial nephritis
Bladder Outlet Obstruction
Often in pts with underlying BPH or neurological disease
Onset may be gradual or sudden; anticholinergic medications
and narcotics pain medications may contribute
Foley catheter insertion, renal US
Post-obstructive diuresis may result in severe dehydration and
hyponatremia
Case 6
55 year old woman diagnosed with pneumonia with
pleuritic chest discomfort in the ER, and is started on
ceftriaxone and azithromycin.
Admission labs: WBC 18k, BUN 30, Cr 1.5 (baseline Cr 0.6
about 1 year ago).
The following AM, despite fluids overnight, her Cr is up to
2.3, BUN 26. Vitals are stable, and she is feeling somewhat
improved.
UA 2+ WBC
Una = 50
FENA = 1.5
Case 6
What is the most likely reason for her AKI?
A. ATN due to volume depletion
B. Volume overload
C. Urinary obstruction
D. Urinary tract infection
E. Acute interstitial nephritis
Acute “Allergic” Interstitial Nephritis
Most commonly caused by NSAIDs, antibiotics (e.g.
penicillins, cephalosporins and others), infection
May present with fever, rash, joint pain and eosinophilia OR
only renal dysfunction (anemia, Na wasting and increased
uric acid common)
UA with pyuria, granular casts, RBCs, urine eosinophils may
be present (but not diagnostic on their own)
Acute Kidney Injury
Rapid increase in Cr (with or without drop in UOP)
Think in buckets: prerenal, intrinsic, post renal
Initial approach
 Physical exam
 “FTD”
 Assess volume, consider fluid challenge
 CBC, urine lytes, UA with microscopy (go spin it yourself!)