Acute tubulointerstitial nephritis Flashcards
Define tubulointerstitial nephritis
Inflammatory diseases of the kidney that mostly do NOT involve the glomeruli, includes tubulo-interstitial and interstitial nephritis broadly.
but, Tubulointerstitial nephritis is a term used mostly for bacterial infections when the renal pelvis is prominently involved, as a part of Pyelonephritis.
Define Acute Interstitial Nephritis
Non-bacterial inflammation of the interstitium and tubules, with inflammatory cell infiltrate, causing rapid decline in kidney function that is usually reversible.
Causes include drugs, irradiation, viruses, and immune reactions, and is the result of
An Type 1 Immune Hypersensitivity reaction, with prominent Eosinophil infiltration of the kidney, and
eosinophils in the urine.
Acute Interstitial nephritis
Analgesic Papillary necrosis.
Causes of acute interstitial nephritis
Causes:
Drugs- 75%
Infections - cause tubulointerstitial nephritis/pyelonephritis 5-10%
Systemic diseases
Sarcoidosis
SLE
Wegener’s
Acute transplant rejection
Irradiation
Symptoms, presentation of acute tubulo-interstitial nephritis
Can often be asymptomatic
Patients are usually normotensive, with no edema.
Bilateral flank pain from swelling and stretching of renal capsule
Oliguria in 50%
In drug induced type, occurs 3-21 days after drug.
Fever,
Hives/macropapular rash
Joint pain
Lab findings in acute interstitial nephritis
Causes a rapid onset AKI: azotemia and lowered GFR, with leukocyte casts in the urine.
Interstitial nephritis is the most common intra-renal cause of AKI, so may be brown necrotic casts in the urine as well.
Blood:
Eosinophilia and increased IgE if drug induced
Mild proteinuria, not nephrosis
Sterile urine culture (unles acute pyelonerphritis)
Viral seroulogy if caused by viruses.
Urine:
Leukocyte casts are the main finding, with eiosinophiluria in drug induced form (not sensitive or speciftc though)
Only few/normal RBC levels, and no RBC casts. RBC casts would suggest a glomerulonephritis instead.
Ultrasound:
Kidneys may be normally sized, or enlarged with cortical edema.
Diagnosing Acute interstitial nephritis
Symptoms + Luekocyte casts in urine, but not totally sure its AIN = Renal biopsy
Differential diagnosis:
GN
ATN
outflow obstruction
Acute interstitial nephritis histology
Interstitial edema
Leukocyte infiltration, including lymphocytes, eiosinophils, and monocytes
AIN often causes Acute Tubular Necrosis, so this may be seen as well
Chronic interstitial nephritis will cause interstitial fibrosis.
granulomas may be seen if its due to sarcoidosis.
Treating acute interstitial nephritis
Prognosis
Remove offending drug or treat underlying disease
Treat symptoms
Treat with steroid therapy if no improvement occurs within 2-4 days after removing the offending drug.
Azotemia should be evaluated for dialysis
Treat hypertension and electrolyte disturbances
Give diuretics if there is volume overload
Prognosis:
50% recovery in 2-6 weeks
40% will have chronic renal insufficiency
10% will have progress to total failure and end stage renal disease
Causes of acute pyelonephritis
Almost always from an ascending UTI infection
In rare cases hematogenous from infective endocarditis or in immunocompromised patients.
Presentation of acute pyelonephritis
Acute pyelonephritis is a very serious infection that is organ-threatening and possible life-threatening.
Fever/chills Flank pain Nausea, vomiting Macroscopic hematuria ~40% Painful urination - UTI
In elderly:
confusion, mental change
decompensation of HF
constipation
What is a complicated vs uncomplicated pyelonephritis
Uncomplicated:
A non-pregnant adult, without other risk factors, typically an E. Coli infection
People in whom it is always complicated: Infants Elderly Preggos Immunocompromised/suppressed patients
Risk factors:
- Anatomical abnormality of the kidney or ureters
- Vesicoureteric reflux
- Ureter obstructions - Prostate hyperplasia, Obstruction,
- Catheters, or other foreign bodies in the urinary tract.
-difficullt/uncommon infectious agent: Klebsiella, Proteus, Enterococci, Pseudomonas, Yeast
Laboratory values for Acute pyelonephritis
Leukocytosis, elevated CRP, systemic signs of inflammation
Decreased kidney function, Azotemia
Urine:
- Significant sedimentation:
- Pyuria
- White cell casts
- Bacteria
- Possible macroscopic hematuria, but RBCs are isomorphic
- Take urine sample for CULTURE before giving antibiotics. Will have positive urine culture.
- Positive leukocyte esterase and nitrile tests- on a urine dipstick.
Acute pyelonephritis diagnosis and management
Symptoms and urine/blood labs should indicate,
Perform Ultrasound and/or CT scan to rule out tract obstruction.
Biopsy is not usually needed.
Acute pyelonephritis complications
Abscess formation
Perirenal abscesses
Sepsis, multi-organ failure
Interstitial nephritis AKI Chronic pyelonephritis/chronic interstitial nephritis Chronic insufficiency ESRD
Treating acute pyelonephritis
Supportive fever, and treat infectious agent.
Remove catheters
Surgical abscess drainage
Targeted antibiotics based on culture sensitivity. Usually 10-14 day antibiotic treatment.
Empiric antibiotics: Beta-lactams, Fluoroquinolones, Aminoglycosides, TMP-SMX.
