L’analyse d’urine et les L’analyse d’urine et les glomerulonglomerulonééphritesphrites

Dr Tim MeagherDr Tim Meagher

ExamExamOOne Canadane Canada

AQTV, QuAQTV, Quéébec, 2008bec, 2008

L’analyse d’urineL’analyse d’urine

ApparenceApparence gravitgravité spécifiqueé spécifique Cellules: leucocytes, globules rouges Cellules: leucocytes, globules rouges hhéémoglobinemoglobine ProtProtééinesines bactbactérieséries Cylindres, rouges, blancs, hyalineCylindres, rouges, blancs, hyaline

GravitGravité spécifiqueé spécifique

Une mesure de concentrationUne mesure de concentration Plus l’urine est concentrPlus l’urine est concentré plus la GS est é plus la GS est

elevéelevé Plus l’urine est diluPlus l’urine est dilué plus la GS est basé plus la GS est bas La GS dLa GS dépend desépend des tubules tubules

HHéématuriematurie

Globules rouges ou hGlobules rouges ou héémoglobinemoglobine Gloubules rouges proviennent du rein Gloubules rouges proviennent du rein

ureturetère, véssie ou prostateère, véssie ou prostate > 5 m> 5 mééritent une investigationritent une investigation

LeucocytesLeucocytes

PyuriePyurie proviennent du rein, uretproviennent du rein, uretère, véssie, ère, véssie,

prostate, ou urèthreprostate, ou urèthre Cystite Cystite Peuvent etre assures sans investigationPeuvent etre assures sans investigation

BactBactérieséries

DDénotent inflammationénotent inflammation Infection (cystite, pyelonéphrite)Infection (cystite, pyelonéphrite) Néphrite interstitielleNéphrite interstitielle

– Medicaments, rMedicaments, réaction allergiqueéaction allergique Asymptomatique ou symptomatiqueAsymptomatique ou symptomatique AccompagnAccompagnées de globules blancsées de globules blancs

Cylindres (casts)Cylindres (casts)

Sont des ‘empreintes’ des tubulesSont des ‘empreintes’ des tubules Proviennent des reinsProviennent des reins D’importance variD’importance variéeée Bénins: hyalines, granulaires en petite Bénins: hyalines, granulaires en petite

quantitéquantité Pathologies importantes: granulaires en Pathologies importantes: granulaires en

grande quantité, RBC castsgrande quantité, RBC casts

Protein comes in many sizesProtein comes in many sizes

Size is described in ‘molecular weight’Size is described in ‘molecular weight’ Low molecular weight (small)Low molecular weight (small)

– Light chainsLight chains Medium molecular weight (medium)Medium molecular weight (medium)

– Need an exampleNeed an example High molecular weight (large)High molecular weight (large)

– albuminalbumin

How does kidney handle protein?How does kidney handle protein?

FiltersFilters ReabsorbsReabsorbs Minimally excretesMinimally excretes

Urinary proteinUrinary protein

Some protein is normal!Some protein is normal!– 150 mgs in 24 hours150 mgs in 24 hours

» 10-15 mgs is albumin10-15 mgs is albumin

» Small sized plasma proteinsSmall sized plasma proteins

» Pieces of renal cells Pieces of renal cells

‘‘Proteinuria’ is an Proteinuria’ is an abnormalabnormal amount of amount of protein in urine, protein in urine, – ie > 150 mgs in 24hrs.ie > 150 mgs in 24hrs.

Detecting protein in urineDetecting protein in urine

Dipstick (used in physician offices)Dipstick (used in physician offices)– Trace, 1+, 2+, 3+Trace, 1+, 2+, 3+

» False positive situations existFalse positive situations exist High specific gravity (very concentrated urine)High specific gravity (very concentrated urine) Very alkaline urineVery alkaline urine

» False negative situations existFalse negative situations exist Very low specific gravity (very dilute urine)Very low specific gravity (very dilute urine)

Rule of thumbRule of thumb– Protein level (mgs %) should not exceed SG (last 2 digits)Protein level (mgs %) should not exceed SG (last 2 digits)

» Eg if SG is 1.022, protein should be < 22 mgs%Eg if SG is 1.022, protein should be < 22 mgs%» If SG 1.30 protein should be < 30 mgs%If SG 1.30 protein should be < 30 mgs%

(IV) MEASURING PROTEINURIA

Semiqualitative (Dipstix)

Trace1+2+3+4+

Quantitative

10 - 30 mg/dL31 - 50 mg/dL

51 - 125 mg/dL126 - 300 mg/dL301 mg/dL & up

Detecting protein in urine (2)Detecting protein in urine (2)

QuantitativeQuantitative– Spot measurement- usually recorded in mgs% Spot measurement- usually recorded in mgs%

or mmol/Lor mmol/L– 24 hour urine collection24 hour urine collection

» Measure protein and creatinineMeasure protein and creatinine Cumbersome, inconsistent and unreliableCumbersome, inconsistent and unreliable < 1G creatinine excreted: likely an incomplete collection< 1G creatinine excreted: likely an incomplete collection

Contaminants

<1% Paraproteins

Albumin

Sloughed Renal Cells

RBCs, WBCs

PROTEINURIA (INSURANCE POPULATION)

viz. 60% of cases of increasedprotein in urine in insurancepopulation = due to increasedalbumin

Detecting protein in urine (3)Detecting protein in urine (3)

protein/ creatinine ratioprotein/ creatinine ratio– Independent of specific gravity or urinary Independent of specific gravity or urinary

volumesvolumes– > 0.2mgs/ G creatinine is abnormal> 0.2mgs/ G creatinine is abnormal

» 0.2-1.5 suggests tubular disease0.2-1.5 suggests tubular disease

» > 1.5 suggests glomerular disease> 1.5 suggests glomerular disease

Detecting protein in urine (4)Detecting protein in urine (4)

Albumin/creatinine ratioAlbumin/creatinine ratio– Proteinuria may be due to non-renal sourcesProteinuria may be due to non-renal sources

» Prostate, vaginal. RBC’s WBC’sProstate, vaginal. RBC’s WBC’s

– albuminuria is specific for renal diseasealbuminuria is specific for renal disease» < 30mgs / 24 hours is N (< 3 mgs%)< 30mgs / 24 hours is N (< 3 mgs%)

» ‘‘Microalbuminuria’Microalbuminuria’ is 30-300 mg/24h. (3-30mgs%) is 30-300 mg/24h. (3-30mgs%)

» ‘‘Macroalbuminuria’Macroalbuminuria’ is > 300 mg/24h. (> 30mgs%) is > 300 mg/24h. (> 30mgs%)

– Albumin/ creatinine ratio > 0.3 is Albumin/ creatinine ratio > 0.3 is abnormalabnormal

Measuring urinary albuminMeasuring urinary albumin

Albumin Albumin (mgs/dl)(mgs/dl)

Alb/creat Alb/creat (mgs/G)(mgs/G)

Alb/creatAlb/creat

mgs/mmolmgs/mmol

24h. urine 24h. urine albumin albumin (mgs)(mgs)

NormalNormal < 3< 3 < 30< 30 < 2.5< 2.5 < 30< 30

MicroalbMicroalb < 30< 30 30-30030-300 2.5-252.5-25 30-30030-300

MacroalbMacroalb > 30> 30 > 300> 300 > 25> 25 > 300> 300

Why measure albumin in urine?Why measure albumin in urine?

Better index of glomerular diseaseBetter index of glomerular disease As glomerular disease progresses As glomerular disease progresses

albuminuria appears first. This is called albuminuria appears first. This is called ‘microalbuminuria’‘microalbuminuria’

As amount of albumin increases we use the As amount of albumin increases we use the term ‘macroalbuminuria’ or ‘proteinuria’ term ‘macroalbuminuria’ or ‘proteinuria’ (as dipstick for protein is now positive)(as dipstick for protein is now positive)

Benign proteinuriasBenign proteinurias

Intermittent proteinuriaIntermittent proteinuria Postural or ‘orthostatic’Postural or ‘orthostatic’

– N supine; elevated when uprightN supine; elevated when upright Exercise-inducedExercise-induced Febrile illnessesFebrile illnesses Contaminants: seminal, prostatic, vaginal Contaminants: seminal, prostatic, vaginal

fluidsfluids

Pathologic proteinuriasPathologic proteinurias

Constant proteinuriasConstant proteinurias– > 1/3 specimens (insurance)> 1/3 specimens (insurance)– > 3 months duration (clinical)> 3 months duration (clinical)

AlbuminuriaAlbuminuria– MicroalbuminuriaMicroalbuminuria– MacroalbuminuriaMacroalbuminuria

Bence-Jones proteinuriaBence-Jones proteinuria

Don’t jump to conclusions!Don’t jump to conclusions!

Albumin levels varyAlbumin levels vary– posture, exercise, fever, otherposture, exercise, fever, other

Creatinine levels varyCreatinine levels vary– Handling delays reduce urine creatinineHandling delays reduce urine creatinine– creatinine production decreases with creatinine production decreases with

» Increasing ageIncreasing age» Older women in particularOlder women in particular

50% of abnormal results will be normal with re-50% of abnormal results will be normal with re-testing!testing!

Significant proteinuiasSignificant proteinuias

GlomerularGlomerular– Glomerulus is ‘leaky’Glomerulus is ‘leaky’– Too many proteins are making way into tubuleToo many proteins are making way into tubule

TubularTubular– Tubules are not reabsorbingTubules are not reabsorbing

overflowoverflow– Capacity of tubules to reabsorb is overwhelmedCapacity of tubules to reabsorb is overwhelmed– Tubules are working normallyTubules are working normally

structure of glomerulusstructure of glomerulus

arteriole

collecting duct

to bladder

normal glomerulus