Paulson - Kidneys 101 Flashcards by Alice Richards

3 fxns of kidneys

filtration of blood

regulation of blood volume

produce erythropoietin

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basic functional unit of kidney

nephron

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components of nephron

glomerulus

renal tubule

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site of blood filtration

glomerulus

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site of water/salts resorption

renal tubule

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fxns of proximal convoluted tubule (PCT) (4)

reabsorption of 60% of glomerular filtrate

secretion of large/protein bound drugs/toxins

passive water reabsorption

ammonia production from glutamine

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what % of Na, K+, and Ca are reabsorbed in the PCT

65%

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what % of phosphate, water, and bicarb are reabsorbed in the PCT

80%

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what % of glucose and aa are reabsorbed in the PCT

100%

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4 segments of the loop of henle

thin descending limb (DLH)

thin ascending limb (ALH)

medullary thick ascending limb (mTALH)

cortical thick ascending limb (cTALH)

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overall fxns of loop of henle (2)

creates a concentration gradient

forms concentrated urine

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fxn of distal convoluted tubule

sodium and calcium reabsorption

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% of sodium reabsorbed in DCT

5-10%

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% of calcium reabsorbed in DCT

10-15%

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DCT reabsorption is regulated by (2)

PTH

vit D

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fxns of collecting tubule (7)

NaCl reabsorption

bicarb reabsorption

water reabsorption → urine concentration

K+ excretion

H+ excretion

urea excretion

regulation of urine volume

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summary of nephron fxn

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acute renal fxn (ARF) is same same

acute kidney injury (AKI)

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arf is characterized by quickly rising __

and accumulation of __ in blood

BUN/Cr

nitrogenous waste

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3 types of causes of arf

prerenal

postrenal

intrarenal

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there is no particular race/age more at risk for arf, but 3 rf include

hospitalized

ICU

post general surgery

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3 general definitions of ARF/AKI

abrupt (w.in 48 hr) increase in Cr of 0.3 mg/dl above baseline

Cr increase 50% or more in past 7 days

oliguria of <0.5 ml/kg/hr for > 6 hr

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sx of arf/aki (lots!)

weakness/lethargy

anorexia

n/v

malaise

pruritus

diarrhea

drowsiness

hiccups

SOB

dizziness

anuria/oliguria

change in volume status/wt

AMS

edema

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tachycardia and hypotn suggest __ cause of arf/aki

prerenal

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distended bladder, CVA tenderness, enlarged prostate suggest __ cause of arf/aki

postrenal

diagnostic tests for arf/aki (5)

bmp UA/urine microscopy/urine culture measurement of urine output renal US +/- urine spot

urine spot gives info about (3)

osmolality urine sodium urine Cr

life threatening complications of arf/aki (4)

hyperkalemia fluid overload uremia severe metabolic acidosis (pH \<7.1)

what do you think when you see pericarditis and AMS in setting of arf/aki

uremia

indications for dialysis in arf/aki (5)

Cr \> 5-10 mg/dl unresponsive acidosis severe lyte d.o fluid overload uremic complications

mc type of arf/aki

prerenal

reduced effective blood circulating to kidney → absolute reduction in fluid volume

prerenal failure

3 ex of prerenal failure

hemorrhage dehydration volume depletion → CHF, cirrhosis (hepatorenal syndrome)

is prerenal failure reversible

yes! → kidneys themselves are ok if underlying cause is corrected

7 causes of true intravascular volume depletion

hemorrhage burns diuretics dehydration GI losses vomiting diarrhea enteric fisula

5 ex of decreased effective circulating volume

CHF cardiac tamponade aortic stenosis cirrhosis w. ascites nephrotic syndrome

4 ex of impaired renal blood flow

ACEI NSAIDs renal artery stenosis renal vein thrombosis

4 labs that distinguish prerenal failure

BUN:Cr ratio urine Na fractional excretion of Na (FENa) urine specific gravity

BUN:Cr ratio suggestive of prerenal failure

20:1 or higher

urine Na suggestive of prerenal failure

\< 20 meq/L

FENa suggestive of prerenal failure

\<1%

urine specific gravity suggestive of prerenal failure

1.020 or higher

lab abnormalities in prerenal failure occur bc

kidney is responding to failure by increasing reabsorption

what does FENa measure

% of Na filtered by kidney that is excreted into urine

tx for prerenal failure

**correct underlying cause:** CHF → diuresis dehydration → IVF hemorrhage → blood/fluids

least common type of arf/aki

postrenal failure

blockage of what 3 portions of kidney are associated w. postrenal failure

ureteres bladder urethra

7 causes of postrenal failure

nephrolithiasis bph obstructing tumor (ex cervical ca) bladder outlet obstruction blood clots w.in urinary tract meds neurogenic bladder uretovesical junction obstruction

s/sx of postrenal arf/aki (4)

abd/groin pain bladder discomfort anuria mass at falnk/suprapubic area/abdomen

2 pe exams for postrenal aki/arf

rectal pelvic

diagnostic tests for postrenal arf/aki (3)

post-void residual US/IVP +/- abd CT

post-void residual \> __ suggets \_\_

100 bladder outlet obstruction

what is IVP

intravenous pyelogram

what do US/IVP give you info about

dilation of ureters or renal pelvis

why would you order abdominal CT for postrenal arf/aki

eval for mass

tx for postrenal arf/aki

**relieve obstruction:** catheterize nephrostomy tube stenting lithotripsy mass excision

damage/dysfxn to one or both kidneys

intrinsic renal failure

intrinsic renal failure can occur \_\_ or \_\_

rapidly gradually

5 causes of intrinsic renal failure

acute tubular necrosis (ATN) nephrotoxins interstitial diseases glomerulonephritis vascular dz

mc cause of intrinsic renal failure

acute tubular necrosis (ATN)

6 ex of nephrotoxins

NSAIDs contrast agents aminoglycosides cyclosprine A cisplatin heme pigments

interstitial dz's that might cause intrinsic renal failure (3)

acute interstitial nephritis SLE infxn

vascular dz's that might cause intrinsic renal failure (2)

polyarteritis nodosa vasculitis

labs that define intrinsic renal failure (4)

BUN:Cr ratio urine Na FENa urine specific gravity

BUN:Cr ratio suggestive of intrinsic renal failure

10-15:1

urine Na suggestive of intrinsic renal failure

40 meq/l or higher

FENa suggestive of intrinsic renal faiure

2% or higher

urine specific gravity suggestive of intrinsic renal failure

1.010-1.020

3 major causes of ATN (mc cause of intrinsic arf/aki)

renal ischemia nephrotoxins sepsis

postischemic ATN can be caused by

all causes of severe prerenal dz

what do you think when you see, **muddy brown granular epithelial cell casts and free renal tubular epithelial cells**

classic UA findings of ATN

lab findings suggestive of ATN

FENa, BUN:Cr ratio, urine specific gravity, and urine osmolality consistent w. intrinsic AKI +/- hyperkalemia and metabolic acidosis

tx for ATN (3)

avoid nephrotoxins tx underlying cause +/- diuretics

diuretic tx for ATN should be avoided in pt w.

oliguria

most pt's spontaneously recover from ATN; better prognosis if they are

nonoliguric

t/f: ATN pt may never fully return to baseline renal fxn

ATN during hospitalization is associated w.

higher mortality

immune-mediated process of tubulointerstitial injury causes inflammatory infiltrate in the interstitium

acute interstitial nephritis (AIN)

mc cause of AIN

meds

meds that cause AIN

cephalosporins penicillins allopurinol diuretics NSAIDs sulfonamides

besides meds, other causes of AIN (7)

**illness:** legionella CMV streptococcus myobacterium EBV candida SLE sarcoidosis sjorgen's

what do you think when you see: **fever, maculopapular rash, eosinophilia**

AIN

UA findings for AIN (4)

WBCs white cell casts +/- esosinophils protein

tx for AIN

stop offending med tx underlying cause **glucocorticoids**

renal glomeruli are damaged by deposition of inflammatory proteins in the glomerular membrane

glomerulonephritis

2 types of glomerulonephritis

focal diffuse

causes of focal glomerulonephritis

henoch-schonleinpurpura postinfectious IgA nephropathy hereditary nephritis SLE

causes of diffuse glomerulonephritis

postinfectious membranoproliferative SLE vasculitis rapidly progressive GN

4 clinical features of glomerulonephritis

hematuria morning face/eye edema evening feet/ankle edema **HTN**

4 diagnostic features of glomerulonephritis

hematuria → **tea/cola colored urine** **RBCs and RBC casts on UA** mishappen RBCs proteinuria

diagnostic test for glomerulonephritis

renal bx *rarely used*

tx for glomerulonephritis

steroids immunosuppressants/chemo meds