Tubulointerstitial DIseases Flashcards
MCC cause of acute interstitial nephritis
acute allergic reaction to medication (penicillin, cephalosporin, sulfa drugs, diuretics, anticoags, phenytoin, rifampin, PPI)
Other causes of AIN besides allergic rxn
infection (strep/legionella), collagen vascular disease, autoimmune disease (SLE, Sjrogens)
What to ask/look for when suspicious for AIN?
- recent infection?
- start a new med?
- fever, general aches/pains?
- signs of AKI?
Clinical features of AIN
- AKI
- rash, fever, eosinophilia (CLASSIC FINDINGS)
- pyuria/hematuria may be present
Tests/findings to diagnose AIN
- renal function tests (azotemia, AKI)
- urinalysis (eosinophils are suggestive!, also may see proteinuria/microscopic hematuria
- renal biopsy to distinguish between ATN and AIN (not usually done)
Treatment for AIN
remove offending agent (usually does the most help)
steroids may help if that doesn’t fully work
treat infection if present
Renal papillary necrosis can be seen in what conditions?
- analgesic nephropathy
- DM nephropathy
- sickle cell
- urinary tract obstruction
- UTI
- chronic alcoholism
- renal transplant rejection
How to diagnose renal papillary necrosis
excretory urogram (changes in papilla/medulla)
What agents can cause analgesic nephropathy
phenacetin, acetaminophen, NSAIDs, aspirin
may lead to acute or chronic renal failure
Features generally common to all RTAs
non-anion gap hyperchloremic metabolic acidosis, with glomerfular function normal
decrease in H+ excreted in urine leading to acidemia and urine alkalosis
Type 1 and type 2 RTA (distal vs. proximal?)
type 1 - distal
type 2 - proximal
Inability to secrete H, urine pH > 6 (normal around 4.7), hypokalemic + hyperchloremic nonanion gap metabolic acidosis, nephrolithiasis and nephrocalcinosis
type 1 RTA
causes of type 1 RTA
congenital, multiple myeloma, nephrocalcinosis, nephrotoxicity (amphotericin B), autoimmune diseases (SLE, Sjrogens), medullary sponge kidney, analgesic nephropathy
Treatment for type 1 RTA
- correct acidosis (sodium bicarb), also helps prevent kidney stones
- phosphate salts (promotes excretion of acid)
inability to reabsorb HCO3
increased excretion of bicarb in urine
hypokalemic hyperchloremic nonanion gap metabolic acidosis
NO nephrolithiasis/nephrocalcinosis
type 2 RTA (proximal)
Treatment for type 2 rta
treat underlying cause DO NOT GIVE BICARB to correct acidosis (it will just be excreted in urine) sodium restrict (this leads to increased sodium reabsorption and thus bicarb reabsorption in proximal tubule)
Causes of type 2 RTA
fanconi syndrom (in children) cystinosis, wilson's disease, lead toxicity, multiple myeloma, nephrotic snydorme, amyloidosis
What should be always be ruled out in type 2 RTA patient
multiple myeloma (excretion of monoclonal light chains)
FIndings in Type 4 RTA
- decreased NA absorptoin H and K secretion in distal tubule
- hyperkalemia and acidic urine
- rare to see nephrolithiasis and nephrocalcinosis
- nonanion gap metabolic acidosis still occurs
Autosomal recessive inheritance of defective amino acid transporter -> results in decreased intestinal and renal reabsorption of neutral amino acids such as tryptophan leading to nicotinamide deficiency
hartnup syndrome
How does hartnup syndrome present?
similar to pellagra: dermatitis, diarrhea, taxia, and psychiatric disturbances
How to treat hartnup syndrome
give supplemental nicotinamide if patient is symptomatic
Fanconi syndrome is a hereditary or acquired proximal tubule dysfuciton that leads to defective transport of what?
glucose, aminoa accids, sodium, K, phsophate, uric acid, and bicarp
What are some problems seen in Fanconi syndrome
- glucosuria
- phosphaturia (leads to rickets/impaired growth in children, osteomalacia, osteoporosis, fractures
- proteinuria
- polyuria
- dehydration
- type 2 RTA
- hypercalciuria
- hypokalemia
