Nephrology Flashcards
first step in evaluating renal failure
- PRErenal (perfusion)
- RENAL (parenchymal)
- POSTrenal (drainage)
clues renal failure is ACUTE
- normal kidney size
- normal hematocrit
- normal Ca2+
clues renal failure is CHRONIC
- smaller kidneys
- renal failure of more than 2 weeks will drop Hct (decreased erythropoietin production)
- Ca2+ levels drop (decreased vitamin D hydroxylation)
causes of PRErenal azotemia
- ANY cause of hypOperfusion
- hypOtension (SBP less than 90)
- hypOvolemia (dehydration or blood loss)
- low oncotic pressure (low albumin)
- CHF (heart can’t PUMP)
- constrictive pericarditis (heart can’t FILL)
- RAS
characteristic diagnostic tests for PRErenal azotemia
- BUN:Cr ratio of more than 15:1, and often more than 20:1
- LOW urinary Na+ (less than 20)
- urine osmolality more than 500
- may have hyaline casts on UA
treatment for PRErenal azotemia
treat UNDERLYING cause
mechanism of BUN elevation in PRErenal azotemia
low volume status, increases ADH, and ADH increases urea transporter activity in collecting duct
causes of POSTrenal azotemia (postobstructive uropathy)
- stones
- strictures
- cancer
- neurogenic bladder (MS or DM)
BUN:Cr ratio seen in POSTrenal azotemia
also more than 15:1
clues to obstructive uropathy
- distended bladder on exam
- large volume diuresis after Foley catheter placement
- B/L hydronephrosis on US
what must be true in order for postobstructive uropathy to cause renal failure?
MUST BE BILATERAL
UNIlateral obstructive cannot cause renal failure
INTRArenal causes of renal failure
- ATN (acute tubular necrosis)
- AGN (acute glomerulonephritis)
- AIN (acute interstitial nephritis)
causes of ATN (acute tubular necrosis)
- either hypOperfusion or toxic injury
- surgery
- severe burns
- aminoglycosides/amphotericin/contrast/chemotherapy
- rhabdomyolysis
causes of AGN (acute glomerulonephritis)
name 11
- Goodpasture’s syndrome
- Churg-Strauss syndrome
- Wegener’s granulomatosis
- polyarteritis nodosa
- IgA nephropathy (Berger’s disease)
- Henoch-Schonlein purpura
- poststreptococcal glomerulonephritis
- cryoglobulinemia
- lupus nephritis
- Alport syndrome
- TTP/HUS
causes of AIN (acute interstitial nephritis)
- antibiotics
- NSAIDs
- infection (e.g. Streptococcus, viral, Legionella)
characteristic diagnostic tests for INTRArenal renal failure
- BUN:Cr ratio of 10:1
- urinary sodium more than 40
- urine osmolality less than 350
how many days of use does it usually take for aminoglycosides to cause kidney damage?
4-5 days
mechanism of rapid onset of renal failure with contrast agent
- directly toxic to kidney tubules
- also, causes intense vasoconstriction of Afferent arterioles (decreased perfusion)
(hypOperfusion = LOW urine sodium)
what does UA show in ATN?
“muddy brown,” or granular casts
treatment for ATN
NO specific therapy
adverse effect of cyclophosphamide
hemorrhagic cystitis
cause of renal failure from rhabdomyolysis
direct TOXIC effect of MYOGLOBIN on kidney tubule
causes of rhabdomyolysis
- crush injury
- seizure
- cocaine toxicity
- prolonged immobility
- hypOkalemia resulting in muscle necrosis
- recent initiation of STATIN
best INITIAL test for rhabdomyolysis
UA (large blood)
rhabdomyolysis labs:
- CPK level
- potassium level
- calcium level
- serum bicarbonate level
- ELEVATED CPK
- hypERkalemia
- hypOcalcemia
- decreased bicarb
MOST ACCURATE test for rhabdomyolysis
urine myoglobin
mechanism of hypOcalcemia in rhabdomyolysis
damaged sarcolemma outside of SER can bind as much Ca2+ as it wants
treatment for rhabdomyolysis
- NS bolus
- mannitol (decrease contact time of myoglobin with the tubules)
- alkalinization of urine (decreases precipitation of myoglobin in the tubules)
suicide by antifreeze ingestion (ethylene glycol)
HAGMA
oxalate crystals
best INITIAL test for ethylene glycol poisoning
UA (envelope-shaped oxalate crystals)
best INITIAL treatment for ethylene glycol poisoning
- ethanol or fomepizole
- with IMMEDIATE dialysis
tumor lysis syndrome
uric acid crystals
treatment for tumor lysis syndrome
- hydration
- allopurinol
- rasburicase
rasburicase MOA
breaks down uric acid
what to do in a patient who MUST have a radiologic procedure with contrast and renal insufficiency
hydrate with NS, and give bicarbonate and N-acetylcysteine
diagnostic clues for AIN
- medication ingestion
- fever and rash
- UA shows white cells (can’t discern between neutrophils and eosinophils)
MOST ACCURATE test for eosinophils in UA
Wright stain or Hansel’s stain
treatment for AIN
no specific therapy, resolves on its own
ALL forms of glomerulonephritis (GN) can have the following:
5 findings
- RBCs in urine
- red cell casts in urine
- mild proteinuria (less than 2G/24H)
- may lead to nephrOtic
- edema
MOST ACCURATE test for GN (but not always necessary)
kidney biopsy
diagnostic clues for Goodpasture syndrome
- COUGH
- HEMOPTYSIS
- SOB
- lung findings (e.g. diffuse infiltrates)
best INITIAL test for Goodpasture syndrome
anti-basement membrane Abs
MOST ACCURATE test for Goodpasture syndrome
kidney biopsy = LINEAR DEPOSITS
treatment for Goodpasture syndrome
plasmapheresis and steroids
diagnostic clues for Churg-Strauss syndrome
- ASTHMA
- COUGH
- EOSINOPHILIA
best INITIAL test for Churg-Strauss syndrome
CBC (check eosinophil count)
MOST ACCURATE test for Churg-Strauss syndrome
kidney biopsy
best INITIAL treatment for Churg-Strauss syndrome
glucocorticoids (e.g. prednisone)
what do you do for Churg-Strauss syndrome if NO response to prednisone?
ADD cyclophosphamide
diagnostic clues for Wegener granulomatosis (now known as, granulomatosis with polyangiitis)
- SINUSITIS, or OTITIS (biggest clues to diagnosis, and main distinguishing factor between Goodpasture syndrome)
- lung findings (e.g. nodules)
best INITIAL test for granulomatosis with polyangiitis
c-ANCA (antineutrophil cytoplasmic Abs)
MOST ACCURATE test for granulomatosis with polyangiitis
kidney biopsy
best INITIAL treatment for granulomatosis with polyangiitis
cyclophosphamide and steroids
diagnostic clues for polyarteritis nodosa (PAN)
- systemic vasculitis with involvement of every organ EXCEPT the lungs
- MULTIPLE MOTOR DEFICITS
- SENSORY NEUROPATHY WITH PAIN
(are key to diagnosis)
best INITIAL test for PAN
ESR
MOST ACCURATE test for PAN
SURAL nerve biopsy, or kidney biopsy
what should be tested for in PAN?
hepatitis B and C (30% association)
what test for PAN can spare the need for biopsy?
angiography showing “beading”
best INITIAL treatment for PAN
steroids and cyclophosphamide
diagnostic clues for IgA nephropathy (Berger’s disease)
- PAINLESS RECURRENT HEMATURIA
- Asian
- recent viral respiratory tract infection
best INITIAL test for IgA nephropathy
NO specific test (IgA may be elevated…)
complement levels are normal
MOST ACCURATE test for IgA nephropathy
kidney biopsy is ESSENTIAL
treatment for IgA nephropathy
NO proven effective therapy
- steroids: for sudden worsening of proteinuria
- ACEIs: used for all patients with proteinuria
diagnostic clues for Henoch-Schonlein purpura
- child or adolescent
- RAISED, NONTENDER, PURPURIC SKIN LESIONS (especially on buttocks and LE’s)
- abdominal pain
- possible bleeding
- joint pain
best INITIAL test for Henoch-Schonlein purpura
clinical
MOST ACCURATE test for Henoch-Schonlein purpura
kidney biopsy = IgA deposition
not necessary though
treatment for Henoch-Schonlein purpura
NO specific therapy; RESOLVES SPONTANEOUSLY
diagnostic clues for post-streptococcal glomerulonephritis (PSGN)
- dark, “tea,” or “cola” colored urine
- PERIORBITAL EDEMA
- HTN
- can occur after throat and skin infections
best INITIAL test for PSGN
- antistreptolysin O (ASLO)
- anti-DNase
- antihyaluronidase
- LOW complement levels
MOST ACCURATE test for PSGN
kidney biopsy = SUBepithelial IgG and C3 deposits
but should NOT always be done; blood test are usually enough
treatment for PSGN
- PCN or other antibiotics for infection
- diuretics for HTN and edema
diagnostic clues for cryoglobulinemia
- h/o hepatitis C with renal involvement
- joint pain
- purpuric skin lesions
best INITIAL test for cryoglobulinemia
- serum cryoglobulin component levels
- LOW complement levels (especially C4)
MOST ACCURATE test for cryoglobulinemia
kidney biopsy
treatment for cryoglobulinemia
- hepatitis C genotype 1: ledipasvir and sofosbuvir
- for treatment-experienced pts: add ribavirin
- for other genotypes: sofosbuvir and ribavirin
diagnostic clues for lupus nephritis
- h/o SLE
what does drug-induced lupus spare?
kidney and brain
best INITIAL test for lupus nephritis
- ANA and anti-dsDNA Ab
MOST ACCURATE test for lupus nephritis
kidney biopsy
very important; not for diagnosis, used to determine extent of disease, which determines therapy
treatment for lupus nephritis: sclerosis ONLY
NO treatment
treatment for lupus nephritis: mild disease, early stage, nonproliferative
steroids
treatment for lupus nephritis: severe disease, advanced, proliferative
mycophenolate mofetil AND steroids
diagnostic clues for Alport syndrome
- congenital
- eye and ear problems (deafness)
- renal failure in second/third decade of life
treatment for Alport syndrome
- NO specific treatment
HUS triad (think about the name)
- intravascular hemolysis
- elevated creatinine
- thrombocytopenia
(h/o E. coli O157:H7)
TTP findings (again, think about the name)
- intravascular hemolysis
- elevated creatinine
- thrombocytopenia
PLUS
- fever
- neurological abnormalities
treatment for HUS
supportive; do NOT treat with antibiotics
treatment for TTP
plasmapheresis in SEVERE cases; do NOT treat with platelets
ANY of the glomerulonephritides can lead to?
nephrOtic syndrome
nephrOtic syndrome has the following:
- hypERproteinuria (more than 3.5G/day)
- hypOproteinemia
- hypERlipidemia
- edema
- HTN
- thrombosis
best INITIAL test for nephrOtic syndrome
UA; shows markedly elevated protein level
NEXT best test for nephrOtic syndrome
spot urine for protein:creatinine ratio; more than 3.5:1
equal in efficacy to 24H urine protein collection
MOST ACCURATE test for nephrOtic syndrome
kidney biopsy
primary renal d/o with NO specific PE findings (only associations): MC in children
minimal change disease
primary renal d/o with NO specific PE findings (only associations): seen in adults with cancer such as lymphoma
membranous
primary renal d/o with NO specific PE findings (only associations): hepatitis C
membranoproliferative