Kidneys 101 Flashcards
3 basic functions of the kidneys?
Filtration of the blood
Regulating blood volume and blood pressure
Producing erythropoietin
The PCT reabsorbs what percentage of glucose and amino acids?
100%
The DCT is mainly involved in reabsorption of?
Sodium and calcium
What two lab values are needed to diagnose and acute kidney injury?
Cr and BUN
What are the 3 categories of renal disorders?
Prerenal
Intrarenal
Postrenal
AKI criteria?
Only need 1 of the following:
Increase in serum creatinine of >/= 0.3 above baseline within 48 hours
Serum creatinine increases >/= 50% in the past 7 days
Oliguria 6 hours
Normal Cr?
0.8-1.2 mg/dL
What is the single most valuable lab test in evaluating an AKI?
BMP
What other diagnostics are helpful for AKI?
Urinalysis, urine microscopy, measurement of urine output, renal ultrasound.
Life threatening complications of AKI?
Hyperkalemia
Fluid overload
Uremia
Metabolic acidosis
In what situations is dialysis indicated?
Serum creatinine >5-10 Unresponsive acidosis Severe electrolyte disorders Fluid overload Uremic complications
AKI is most commonly due to?
Prerenal failure
Prerenal failure is defined as?
Reduced effective blood circulating to kidney
Causes of prerenal failure?
Reduction in fluid volume(hemorrhage, dehydration)
Effective volume depletion(CHF, cirrhosis)
Impaired renal blood flow (renal artery stenosis)
What lab findings are characteristic of prerenal failure?
Serum BUN:Cr ration >20:1
Urine sodium <20meq/L
Urine specific gravity >1.020
Why is urine sodium decreased in prerenal failure?
Kidney tries to increase BP by holding on to sodium and water
Treatment for prerenal failure due to CHF?
Diuresis
Treatment for prerenal failure due to dehydration?
IVF
Treatment for prerenal failure due to hemorrhage?
Blood + fluids
What is the least common type of renal failure?
postrenal failure
Blockage in what areas causes postrenal failure?
Ureters, bladder, urethra
What diagnostic testing would you consider ordering for a patient suspicious for postrenal failure?
Post-void residual, ultrasound or IVP, +/- abdominal CT
Treatment for postrenal failure?
Relieve obstruction
What is intrinsic renal failure?
One or both kidneys have been damaged and do not work properly
Most common cause of intrarenal failure?
Acute tubular necrosis
Other causes of intrarenal failure?
Nephrotoxins
Interstitial diseases
Glomerulonephritis
Vascular diseases
Labs findings suggestive of intrinsic renal failure?
Serum BUN:Cr ratio 10-15:1
Urine sodium > 40meq/L
FENa>2%
Urine specific gravity 1.010-1.020
3 major causes of acute tubular necrosis?
Renal ischemia
Nephrotoxins
Sepsis
Classic UA of ATN?
Muddy brown granular epithelial cell casts and free renal tubular epithelial cells
Treatment for ATN?
Hold nephrotoxins, treat underlying cause, supportive management
T/F? Most patients spontaneously recover renal function after ATN.
True
What is acute interstitial nephritis?
An immune mediated process of tubulointerstitial injury
Most common medications to cause acute interstitial nephritis?
Cephalosporins, penicillins, allopurinol, diuretics, NSAIDs, sulfonamides
What are some non-iatrogenic causes of AIN?
illnesses - legionella, CMV, strep, ect
UA findings in AIN?
WBCs, white cell casts, eosinophils, protein
Treatment for AIN?
Stop offending med
Glucocorticoids
What is glomerulonephritis?
Renal glomeruli are damaged by deposition of inflammatory proteins in the glomerular membrane
What symptoms are classic for AIN?
Fever, maculopapular rash, eosinophilia
Urine findings in glomerulonephritis?
Hematuria, urine may be tea or cola colored.
RBCs and RBC casts on UA.
Misshapen RBCs
Proteinuria
Treatment for glomerulonephritis?
Nephrology consult!
Steroids and immunosuppressants.
