Renal #1 (AKI & Rhabdo) Flashcards
What three lab values are indicative of acute renal failure (acute kidney injury)
-Increased Creatinine
-Decreased GFR
-Increased BUN (urea nitrogen is a waste product kidneys remove from your blood)
MC type of acute renal failure overall
Prerenal Kidney Injury (decreased renal perfusion with nephrons still intact)
Causes of prerenal kidney injury
Think about decreased renal perfusion and what causes this
-Reduced renal perfusion (hallmark)
–Hypovolemia: diuretics, shock, GI loss, blood loss
–Affarent arteriole constriction (NSAIDs, IV contrast)
–Efferent (ACE, ARB’s)
–Hypotension
What diagnostics show to indicate prerenal kidney injury
-Evidence of water/electrolyte conservation
–Increased BUN: Cr ratio (>20:1)
–Fractional excretion of Na <1%
–Concentrated urine: high urine specific gravity (>1.020)
What is the treatment for prerenal kidney injury?
-Volume Repletion to restore volume and renal perfusion
What exactly is acute interstitial nephritis?
What are some causes?
-Intrinsic acute kidney injury characterized by inflammatory or allergic response in the interstitium with sparking of glomeruli and blood vessels
-Drug hypersensitivity (MC): NSAIDs, Penicillins, Sulfa Drugs, Ciprofloxacin, Rifampin, Allopurinol
-Infections, Idiopathic, Autoimmune
Symptoms of AIN?
Fever, eosinophilia, maculopapular rash, arthalgias
What is seen on urinalysis for AIN (remember it is an inflammatory/allergic cause)
-WBC casts and eosinophilia
-Increased serum IgE
Treatment for AIN
-Remove offending agent –> spontaneous recovery
MC type of intrinsic kidney injury.
Explain it
-Acute Tubular Necrosis (ATN)
Acute destruction and necrosis of renal tubules of nephron
There are two MAIN causes of ATN. What are they?
-Ischemic (h/o prerenal injury): prolonged prerenal azotemia associated with hypovolemia or hypotension
-Nephrotoxic: contrast dye, Aminoglycosides (-mycin), Vancomycin. NSAIDs, Rhabdomyolysis, Multiple Myeloma.
What is seen on urinalysis for ATN?
Also explain the urine specific gravity, FENA, and osmolarity
-Epithelial cell casts and granular (muddy brown) casts
-Low urine specific gravity (isosthenuria = inability to concentrate urine)
-Low urine osmolarity (dehydration)
-Increased FENA > 2%
Treatment for ATN
-Remove offending agents and give IVF (first line)
-Furosemide if not urinating
What is acute glomerulonephritis?
What four things are common in glomerulonephritis?
Inflammation of the glomeruli, leading to protein and RBC leakage into the urine.
Hypertension, azotemia, hematuria (RBC casts), and proteinuria (edema)
What is azotemia?
Elevation of BUN and Cr levels in the blood
There are MANY types of acute glomerulonephritis. What is the MCC, who does it affect, and when is it MC after?
IgA Nephropathy (Berger’s Disease): Often affects young males within days (24-48 hours) after URI or GI infection
Another type of glomerulonephritis, post-infectious, is MC after….
Group A Strep infection: 10-14 days after skin (impetigo) or pharyngeal infection
Who should you consider post-infectious glomerulonephritis in (who is the classic presentation in)?
-2-14 year old boy with facial edema up to 3 weeks after Strep with scanty, cola-colored dark urine
What labs are shown in post-infectious glomerulonephritis?
-Increased anti-streptolysin (ASO) titers
-Low serum complement C3
Rapidly Progressive Glomerulonephritis (RPGN) is associated with poor prognosis because it has a rapid progression to end stage renal disease within weeks to months. What is seen on biopsy that makes this diagnosis?
Crescent formation on biopsy
Explain Goodpasture’s Disease along with two symptoms you should remember with this
-Positive anti-GBM antibodies against type IV collagen of the glomerular basement membrane in kidneys and lung alveoli
Acute glomerulonephritis and hemoptysis
REMEMBER, KIDNEYS AND LUNGS
Finally, the last form of glomerulonephritis, vasculitis, has two types. Microscopic Polyangiitis, which is ________, has what positive lab?
Vasculitis of small renal vessels
+ P-ANCA
On the other hand, granulomatosis with polyangiitis (Wegener’s), is _______, has what positive lab?
Necrotizing vasculitis
+ C-ANCA
What are some symptoms of acute glomerulonephritis, in general?
-Hematuria (cola or tea-colored urine)
-Edema (peripheral and periorbital)
-Fever, abdominal or flank pain
-Oliguria (small amount of urine)
-Hypertension
What is seen on labs, in general, for acute glomerulonephritis?
-Hematuria, RBC casts, proteinuria (<3g), high specific gravity
-Increased BUN and Cr
What is the gold standard diagnostic for acute glomerulonephritis, even though not needed in most cases?
What is seen on the following conditions with this diagnostic?
-IgA nephropathy
-Poststreptococcal
-Goodpasture Syndrome
-Renal biopsy
-IgA: IgA mesangial deposits
-PostStrep: immune humps of IgG, IgM, and C3
-Goodpasture: linear IgG deposits in the GBM
Treatment for acute glomerulonephritis
-Usually self-limited with good prognosis
–IgA nephropathy: ACEi
–Edema: Loop Diuretics (edema)
–Hypertension: BB, CCB
–RPGN: Corticosteroids + Cyclophosphamide
Finally, postrenal kidney injury otherwise known as obstructive uropathy, is characterized by _________. This is rare because both kidneys need to be obstructed.
Obstruction of the passage of urine
What are some etiologies of postrenal kidney injury?
-Kidney stones, tumors, BPH, prostate cancer
What is the initial imaging study used in postrenal kidney injury to look for obstruction and hydronephrosis?
US
Treatment for postrenal kidney injury (it’s easy)
removal of obstruction
Rhabdomyolysis, which can be caused from things such as ________, has symptoms such as (there are three)
-Trauma, heat stroke, seizures, cocaine, statin therapy, snake bites, prolonged immobility, crush injuries
Muscle pain + weakness/swelling + dark/tea colored urine
What is the pathophysiology of rhabdomyolysis?
-Muscle breakdown –> myoglobin released (toxic to kidneys/plugs it up) –> AKI/ATN
What is the most specific diagnostic that can be done for rhabdomyolysis and what does it show?
Urine Analysis/Dipstick: positive for heme but negative for RBC’s
On an ECG for rhabdomyolysis, you should look for _________, which is displayed by _________
Hyperkalemia
Increased/High T Wave
Furthermore, in rhabdomyolysis, Creatinine Kinase (muscle enzymes) will be
Very high (5x normal)
What is the treatment for rhabdomyolysis?
IVF +/- Mannitol (Diuretic) or Sodium Bicarb (alkalize urine)
Mannitol, a diuretic, works mainly where?
It increases urine volume by drawing fluid from intracellular compartment and increasing tubular osmolarity.
Proximal tubule
What is one adverse effect of Mannitol that you should remember?
Pulmonary edema (due to increased fluid shifts)
What are 4 main indications to use Mannitol as treatment?
-Increased ICP
-Increased IOP
-Promotes diuresis in AKI
-Increases excretion of toxic metabolites (rhabdomyolysis)
Loop Diuretics, such as ______, ______, or _______, are the strongest class of diuretics. What do they do?
Furosemide, Bumetanide, Torsemide
Inhibits water, Na+, K+, Cl- transport as well as Ca+ and Mg+ absorption across the thick ascending limb of the Loop of Henle, leading to dilute urine.
What is Ethacrynic Acid?
Medication similar to Furosemide that can be used if Sulfa Allergy and safe in patients with gout. However, associated with higher risk of ototoxicity.
What is one adverse effect of Loop Diuretics that should be remembered (remember what it does).
-Decreased electrolytes: hypokalemia, hypocalcemia, hypomagnesemia
-Ototoxicity
-Hyperglycemia
-Hyperuricemia
