肾功能检验-医药类课件.ppt

1、Laboratory tests of renal functionAnatomy of KidneyFunctions of the kidneyExcretion of Metabolite Waste:urea,uric acid,creatinineUrine Production,regulation of homeostasis,water,acid base balanceEndocrine Function:renin,erythropoietin,1,25-dihydroxycholecalciferolRenal function testsDetect renal dam

2、ageMonitor functional damageDistinguish between impairment and failureKidney FunctionA plumbers viewFilterProcessorInputArterialOutputVenousOutputUrineHow do you know its broken?NO Urine!Clinical symptomsTestsFilterProcessorInputArterialOutputVenousOutputUrineWhere can it break?Pre-renalRenalPost-re

3、nalFilterProcessorInputArterialOutputVenousOutputUrineLaboratory tests of renal functionGlomerular Function TestsRenal Tubular Function TestsSection 1 Investigation of Glomerular FunctionRenal Blood Flow:1200-1400ml/minRenal Plasma:600-800ml/min20%of plasma:glomerular filtration GFR:Glomerular Filtr

4、tion Rate Concept Renal CleranceConcept Virtual volume of plasma from which the substance in question has been completely removed during a given time interval.C=UV/P U:urine concentrtion P:plasma con.V:urine flow rateUsefulness of Renal CleranceFreely filtrated,neither secreted,nor reabsorbed:Inulin

5、:GFR DeterminationFreely Filtrated,small amounts secreted,without reabsorption:Cretinine:GFRFree filtrated,completely reabsorption:Glucose Tubular Maxima Reabsorption RateInulin ClerancePolymer of fructoseMW:5500Free filtration,without secretion and reabsorptionGFRMethod Reference Interval:2.0-2.3ml

6、/minEndogenous Creatinine Clearance100g,98%stored in musle,MW:113Cretine phosphate-cretinecretinineFreely filtration,small mounts:secretionExogenous and Endogenous CreatinineGrossly Investigate the GFRMethod 24h urine collection method modified 4h urine collection method Clerance Correction：Ccr x SB

7、SA/IBSAPlasma ureaSecreted and reabsorbed by tubules,freely filtratedquick,simple measurementwide reference range 3-8 mmol/Lsensitive but non-specific index of illness Factors influencing plasma urea concentration GIT protein Kidney filtration Liver amino acids Plasma urea reabsorption excretion Tis

8、sue protein Distribution volume Urea excretionfiltered at glomerulusabout 40%filtered urea is reabsorbed by renal tubules in healthmore urea is reabsorbed if rate of tubular flow is slowtubular flow rate is slow when there is renal hypoperfusionIncreased plasma ureaGI bleedtraumarenal hypoperfusiond

9、ecreased RBFdecreased ECFVacute renal impairmentchronic renal diseasepost-renal obstructioncalculustumourUreaUseful test but must be interpreted with great careAlways consider input,output and patients fluid volumePlasma creatinine50-140 umol/Lincreases in concentration as GFR decreasesanalytical in

10、terferences(acetoacetate-DKA)NOT proportional to renal damagePlasma CreatininePlasma creatinine in chronic renal disease May increase to 1000 umol/LPlot of recipricol of plasma creatinine concentration predicts when intervention is required in end stage renal failurePlasma Uric Acid20%:foods;80%:pur

11、ine metabolismSmall amounts:conjugated with albuminFree Filtrated,98%-100%:reabsorbedPlasma UA concentration:depend on glomerular filtration and tubular reabsorptionProgression of chronic renal diseaseCreatinine clearancemL/minPlasma change60-120none30-60increased creatinine,increased urea20-30incre

12、ased potassium,decreased bicarbonate10-20increased phosphate,increased uric acidPlasma Cystatin CCysteine proteinase inhibitorProduced by nucleated cellsMW:13000,free filtration,reabsorbed and metabolized by tubulesPlasma CysC concentrtion:depend on glomerular filtrationCarbamylated hemoglobinUreabl

13、oodcyanateHb carbamylatedCarHbARF：no changes(1 weeks)CRF:increaseLaboratory tests of renal functionglomerular filtration rate impracticalcreatinine clearance unreliableplasma creatinine specific but insensitiveplasma urea subject to problemsurine volume often forgotten!Section 2 Investigation of Tub

14、ular FunctionDistal nephron Function tests 1.Mosenthal test Concentration dilution test 8 AM:Voiding and Discarded 10,12,14,16,18,20:00 and 8:00 next day:collecting urine samples Determing the urine volume and gravity2.Urine Osmolarity3.Acute Oliguria Prenal?Renal?Proximal tubular Function tests 1.L

15、ow MW proteins in urine 2.Tubular maximal glucose reabsorption 3.Tubular maximal PAH secretion 4.Amino acide in urine Fanconi SyndromeSection 3 Effective Renal Blood FlowIsotope Method:131I-OIHPAH Clearance:20%:filtrated,80%:secreted by tubulesSection 4 Investigation of renal tubular acidosisTubular

16、 Acidosis:I,II,III.IVI:distal formII:proximal formNH4Cl Loading TestOral administration of NH4ClArtificial Metabolic AcidosisUrine Sample CollectionpH determinationFraction of HCO3-excretionHCO3-:85-90%:reabsorbed by proximal tubules;10-15%:reabsorbed by distal tubulesOral Administration of NaHCO3Urine CollectionDetermination of PCr,UCr,PHCO3,UHCO3Caculation:FEHCO3=UHCO3.PCr/UCr.PHCO3