Reading of renal function
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Reading of renal function. YY Chiou. Glomerular filtration rate. Clearance of inulin Clearance of creatinine :normal range Male:120±25 mL/min Female:95±20mL/min Infant:17 mL/min/1.73M 2. P[Inulin] × GFR = U[Inulin] × urine volume. Difference between inulin and creatinine

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Reading of renal function

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Reading of renal function

Reading of renal function

YY Chiou


Glomerular filtration rate

Glomerular filtration rate

  • Clearance of inulin

  • Clearance of creatinine:normal range

    • Male:120±25 mL/min

    • Female:95±20mL/min

    • Infant:17 mL/min/1.73M2


P inulin gfr u inulin urine volume

P[Inulin] × GFR = U[Inulin] × urine volume


Reading of renal function

  • Difference between inulin and creatinine

  • Age effect: age >40y/o -> Ccr decrease 1mL/min/yr

  • Urine Cr collection:

    • Age≦60y/o:male: 20-25mg/kg; female:15-20mg/kg

    • Age>60y/o:10mg/kg


Plasma cr

Plasma Cr


Condition associated with pcr increased and not changed gfr

Condition associated with PCr increased and not changed GFR

  • Increased Cr production

    • Rhabdomyolysis

    • Meat

  • Decreased Cr excretion

    • Cimetidine, triamterene, probenecid, amiloride, trimethoprim, spironolactone

  • Measured bias

    • Endogeneous: ketone, ketoacids, glucose, bilirubin, urate, urea, fatty acid

    • Exogeneous: cephalosporines, 5-FU, phenylacetyl urea, acetoheximide


Estimate ccr

Estimate Ccr

  • Cockcroft and Gault equation: CCr=[(140-age(yr)) ×BW(kg)] ÷[72×Pcr(mg/dl)]

  • Female: above data×0.85

  • 1/Pcr

  • EsGFR(ml/min/1.73M2)=KL(body length, cm) ÷ Pcr

    • K

      • LBW:0.33

      • NB-1yr:0.45

      • 2yr-adolescent girls: 0.55

      • 2yr-adolescent boys:0.77


Reading of renal function

BUN

  • Reverse relationship with GFR, but many confounding factors

  • Urea nitrogen can reabsorb paralleling with Na and H2O resorption

  • BUN:Pcr = 15-20:1


Urinalysis

Urinalysis

  • Urine sample: fresh (30-60min)

  • 3000rpm, 3-5min -> suspension with pellet

  • Color


Urine protein

Urine protein

  • Daily urinary protein:150mg/day

  • Microalbuminuria

  • Detection: dipstick

    • Tetrabromophenol blue dye –albumin

    • Sulfosalicylic acid


Reading of renal function

Protein(mg/dL)dipsticksulfosalicylic acid

00no turbid

1-10traceslight turbid

15-30+1turbid

40-100+2white without ppt

150-350+3white with ppt

>500+4coarse ppt


Urine protein1

Urine protein

  • 24 hr daily protein loss

  • Spot UTP/UCr


Urine ph and osmolality

Urine pH and osmolality

  • Normal range:4.5-8.0

  • How about alkalization urine?

  • Urine sp. Gr. To estimate urine osmolality

  • Plasma osmolality & urine osmolality


Urine na excretion

Urine Na excretion

  • Urine excretion = intake Na amount

  • Urine [Na]<20meq/L

  • Urine [Na]>40meq/L

  • Significance of %FENa


Arf with fena 1

ARF with %FENa <1%

  • Prerenal factor

  • ATN

    • Non-oliguric ATN (10%)

    • Chronic prerenal disease-

    • Contrast media

    • Sepsis

    • Myoglobulinuria or hemoglobulinuria

  • AGN or vasculitis

  • Obstructive nephropathy


Urinary cast

Urinary cast

Hyaline castconc. Urine or diuretics

Red cell castGN or vasculitis

WBC castTIN, APN, GN

Epithelial castATN, GN

Fatty castGN with proteinuria, NS

Granular castproteinuria, degenerative cells

Waxy castCRF


Renal acidification evaluation

Renal acidification evaluation

  • Urinary pH:

  • Net acid excretion:

  • Urinary anion gap:

  • Acidification loading test:


Urine ph

Urine pH

  • Fresh urine

  • Collect in the morning

  • Must rule out UTI

  • Many confounding factors- proton pump, electro-gradient of membrane, buffer conc., diet, et. al.


Net acid excretion

Net acid excretion

  • Total acid excretion=titratable acid + NH4+

  • Net acid excretion=total acid excretion – HCO3- excretion

  • Titratable acid= buffer solution of H3PO4 with urea nitrogen

  • Def. of titratable acid excretion:the amount of NaOH(meq) to elevate UpH to 7.4


Urinary anion gap

Urinary anion gap

  • Total conc. Of anions = total conc. Of cations

  • Na++K++NH4++Ca+2+Mg+2=Cl-+H2PO4-+SO4-+organic anions

  • Na++K++NH4+=Cl-+80

  • Urinary anion gap:Na++K+-Cl-


Urinary acid loading tests

Urinary acid loading tests

  • Acid loading test

  • Sodium sulfate infusion test or furosemide test

  • Buffer loading test


Acid loading test

Acid loading test

  • NH4Cl 0.1g(1.9meq)/kg, po -> collection urine pH and net acid excretion for 2-8hr.(normal: UpH<5.5)

  • CaCl2

  • Arginine HCL

  • Diamox test

Normal urine CO2>80mmHg

U-B[PCO2]>30mmHg


Increase distal tubule na conc test for proton pump or voltage dependent defect

Increase distal tubule Na conc. Test – for proton pump or voltage-dependent defect

  • Furosemide test: 1mg/kg, collect urine pH, net acid excretion and U[k], po 5hr or iv 3hr

    • Reading:UpH increase in 1hr and then UpH down to 5.5 in future 2-4hrs; U[k] and acid increase 2 fold

  • Sodium sulfate


Buffer loading test

Buffer loading test

  • IV drip or 2-3ml/min NaHCO3 100-150mEq(total) till plasma NaHCO3 ≧30meq/L

    • Then check blood and urine pH, [HCO3-], CO2

    • Calculate %FEHCO3-

      • 3-5%

      • >15%

    • U-B[PCO2] >20-30mmHg, when U[HCO3-] >100-150meq/L


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