Tubulointerstitial Disease II Flashcards
What qualifies as acute kidney injury?
• over a period of: 6hrs, 48 hrs, 7 days?
6 hrs:
• less than 0.5 mL/Kg per hour for 6 hours
48 hrs:
•0.3 mg/dL over a 48 hour period
7 days:
• 1.5 times the baseline
What are the 3 major things to look for to determine whether damage is Pre-Renal or Post-Renal?
• subcategories?
ABILITY TO CONCENTRATE URINE:
Fractional Excretion of Na+
• less than 1% = Pre-Renal
• more than 2% = ATN
Urine Na+ concentration
• less than 20 = Pre-renal
• greater than 40 = ATN
Urine Specific Gravity
• greater than 1.018 = pre-renal
• Less than ~1.010 = ATN
GFR:
BUN/Creatinine
• Greater than 20 = pre-renal
• Less than 10-15 = ATN
UNINARY SEDIMENT:
Pre-renal = hyaline casts
ATN = Muddy Brown Granular Casts
What is a good way of determining where injury has occurred Tubular Dysfunction?
• See what is being peed out or what you lack in the serum
What would you expect to see in the urine in proximal tubular injury?
- AMINO ACIDS
- HCO3-
- GLUCOSE
- Protein
- Uric acid
What problems would result from distal tubular injury?
- Potassium
* Hydrogen (acidosis)
What effect does low GFR have on sodium balance?
• Low GFR = POSITIVE Na+ balance because
Acute Intersitial Nephritis
• cells mediating?
• Dose Dependence?
• Recurrence risk?
Cells:
• Immune Mediated Reaction
Dose Dependence:
• NOT DOSE DEPENDENT
Recurrence Risk:
• WILL recur on Re-Exposure
What proteins provide the antigenic stimulus for Acute Interstitial Nephritis?
- Tubular Basement Membrane
- Secreted Tubular Proteins
- Non Renal Proteins (immune complexes)
What causes the immune system to become activated against Tubular Basement Membrane, Secreted Tubular Proteins, and Non-renal proteins in Acute tubular NEHPRITIS?
Drugs or Infectious agents may act:
• as antigens themselves
• as haptens to modify immunogenicity of native renal proteins
• Molecular Mimickery
• Circulating Immune complex precipitation
What Immune Cells are the predominant mediators of Acute Interstitial NEPHRITIS?
• cytokines that play a major role?
• MONONUCLEAR cells, mostly T-CELLS
Cytokines:
• TGF-ß = major cytokine
How do people typically present with ACUTE TUBULAR NEPHRITIS?
• Vignette?
• Signs?
Vignette:
• Started a NEW DRUG 3 wks ago, with a SUDDEN ONSET of renal insufficiency
Signs:
• Hematuria, Sterile Pyuria, Eosinophiluria
Hemolysis and hepatitis may also be present
What drugs are common causative agents in acute drug-induced interstitial Nephritis?
- SYNTHETIC PENICILLINS
- NSAIDs
- PROTON PUMP INHIBITORS
(NSAIDs and H+ inhibitors don’t cause disease in a great percentage of pts., but there wide use makes this rxn common)
Others:
• Rifampin, ciprofloxacin, Diuretics - THIAZIDES, Allopurinol, Cimetidine
What sign should tip you off than an NSAID caused the Acute Interstitial Nephritis?
• who is this most common in?
- PROTEINURIA - this is b/c NSAIDs cause glomerular damage
- Elderly Population experiences this
***Note: you would expect to see an inability to concentrate urine, along with evidence of protein to imply glomerular damage.
What is the most common infectious cause of Acute Interstitial Nephritis?
• Viral Infections
pretty much any bacteria of infectious agent can cause this
AMINOGLYCOSIDE NEPHROTOXICITY
• how does the mechanism of toxicity differ from toxicity of Penicillins, NSAIDs, and Proton pump inhibitors?
• How does it gain access to the area that is causes pathology in?
How does it differ:
• Penicillins, NSAIDs, H+ pump blockers are all toxic to the interstitium
• Aminoglycosides DIRECTLY affect the PROXIMAL TUBULE
Hoes does it get access:
• Megalin pump transports the CATIONIC A.G. into the Tubular cells