Renal Flashcards
Why is aspirin and acetominophen bad for the kidney?
1) Aspirin inhibits PGE2 leading to vasoconstriction of the afferent arteriole, which decreases blood flow to renal medulla 2) Acetominophen creates free radicals that damage renal tubules in the medulla.
How does multiple myeloma affect the kidney?
1) Bence Jones proteins produce tubular casts - the light chains are toxic to renal tubular epithelium. These casts also incite foreign body giant cell reaction involving tubules and interstitium leading to renal failure. 2) Nephrocalcinosis - hypercalcemia secondary to the lytic bone lesions produces metastatic calcification of the basement membrane of collecting tubules, 3) primary amyloidosis producing nephrotic syndrome.
What is can renal osteodystrophy cause?
1) Osteitis fibrosa cystica (Secondary to hypovitaminosis D –> increased PTH –> hyperparathyroidism which increases bone resorption in places like the jaw. 2) osteomalacia (decreased mineralization of the organic bone matrix (osteoid)), 3) osteoporosis (loss of osteoid and mineralized bone) due to chronic metabolic acidosis since bone is used to buffer H+.
What cells secrete renin?
The juxtaglomerular appartatus of the afferent arteriole.
What is the most common cause of death in SLE?
Diffuse proliferative glomerulonephritis. You will see “wire-looping” of capillaries on LM; subendothelial and sometimes intramembranous IgG-based ICs often with C3 deposition.
Why are patients hyperchloremic with non-anion gap metabolic acidosis?
There is an increase in chloride reabsorption to help replace the lost HCO3- in the metabolic acidosis. Diarrhea can cause a metabolic acidosis.
What is hepatorenal syndrome?
condition of intense renal vasoconstriction due to a loss of renal autoregulation occurring as a complication of severe, chronic liver disease (i.e., cirrhosis). It is characterized by splanchnic vasodilation and concomitant vasoconstriction in the renal vascular beds due to the activation of R-A-A-S. GFR is reduced, but kidney anatomy is normal. It leads to a pre-renal azotemia (trying to conserve volume for reabsorbing urea).
What is the best treatment for aspirin overdose?
Sodium bicarbonate to alkalinize the urine. Signs of an aspirin overdose are tinnitus, nausea, vomiting, and lethargy combined with fever and tachypnea.
In patients with renal disease, how do you adjust loading and maintenance doses?
Loading dose (= Cp x Vd / F) should remain the same because this only depends on volume of distribution, no excretion or metabolism. The maintenance dose (= Cp x CL x dose interval / F) should be lowered to due reduced excretion (reduced CL, or clearance).
Patients with Turner syndrome have increased likelihood of developing what renal disease?
Wilm’s tumor (nephroblastoma) - 25-30% of patients with Turner’s syndrome will develop horseshoe kidney, pelvic kidney, or duplicated collecting systems. Horseshoe kidney increases likely (4x) of developing Wilm’s tumor.
What microorganisms can lead to staghorn calculus?
Any urease-producing microorganisms - this includes Staphyloccus species, Ureaplasma, Proteus (most common), Klebsiella, and Pseudomonas. Staghorn calculus are made of ammonium magnesium phosphate, also known as struvite.
What is causes urine to dark color upon being oxidized?
Alkaptonuria, which a deficiency of homogentisic oxidase, an enzyme of tyrosine degradation pathway that converts homogentisic acid to maleylacetoacetic acid. Homogentisic acid when exposed turns a dark black.
Why do patients with alkaptonuria develop arthralgias?
Homogentisic acid is toxic to cartilage.
Why is a horseshoe or pelvic kidney lower down from its usual anatomic position?
The fused kidneys gets stuck on the inferior mesenteric artery.
What is the most common tumor type of the urinary tract system?
Transitional cell carcinoma. It presents with painless hematuria with no casts. Major risk factor is smoking in addition to aniline dyes, phenacetin, and cyclophosphamide.
What are lab values of patients on thiazide diuretics?
Hyperglycemia, metabolic alkalosis, low urinary calcium excretion. Inhibit the Na/Cl cotransporter. The drug attaches to the Cl− site and inhibits Na+ and Cl− reabsorption. This leaves the Na+ channel open for Ca2+ reabsorption. They also lead to hypokalemia becuase thiazide diuretics (most common cause): excessive exchange of Na+ for K+ in late distal and collecting tubules. H+ also secreted a lot from the intercalated disk cells.
What antibiotics are associated with nephrotoxicity?
Aminoglycosides (gentamicin, neomycin, streptomycin, tobramycin, amikacin)
What is the mechanism of action of cyclophosphamide?
It is an alkylating agent that cross-links DNA and prevents DNA synthesis and cell division.
What is tubulointerstitial nephritis (acute or chronic inflammation of tubules and interstitium) commonly cuased by?
Drug toxicity - Penicillin (particularly methicillin), rifampin, sulfonamides, NSAIDS, diuretics
How does tubulointerstitial nephritis present?
Pyuria (classically eosinophils) and azotemia, occurring after administration of drugs that act as haptens, including hypersensitivity.
What usually causes chronic pylonephritis?
Typically requires predisposition to infection such as vesicoureteral reflux or chronically obstructing kidney stones.
What causes the proteinuria associated with MCD?
Effacement of foot processes supporting the epithelial podocytes with weakening of slit-pore membranes. T-cell cytokine release attacks the BM and results in less charge barrier allowing negatively charged proteins like albumin to leak through into urine. Decreased albumin leads to less oncotic pressure in plasma so more fluid goes in interstitium leading to edema. Steroid treatment has a good response.
What is maple syrup urine disease?
Patients can’t degrade branched amino acids (I Love Vermont - isoleucine, Leucine, Valine) due to decreaed alpha-ketoacid dehydrogenase.
