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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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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




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


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


Protein(mg/dL) dipstick sulfosalicylic acid

0 0 no turbid

1-10 trace slight turbid

15-30 +1 turbid

40-100 +2 white without ppt

150-350 +3 white with ppt

>500 +4 coarse 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 cast conc. Urine or diuretics

Red cell cast GN or vasculitis

WBC cast TIN, APN, GN

Epithelial cast ATN, GN

Fatty cast GN with proteinuria, NS

Granular cast proteinuria, degenerative cells

Waxy cast CRF


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 voltage-dependent defect

  • 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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