Avis des hôpitaux du RUIS McGill sur le Projet Hospitalier du
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Transcript Avis des hôpitaux du RUIS McGill sur le Projet Hospitalier du
L’analyse d’urine et les
glomerulonéphrites
Dr Tim Meagher
ExamOne Canada
AQTV, Québec, 2008
L’analyse d’urine
Apparence
gravité spécifique
Cellules: leucocytes, globules rouges
hémoglobine
Protéines
bactéries
Cylindres, rouges, blancs, hyaline
Gravité spécifique
Une mesure de concentration
Plus l’urine est concentré plus la GS est
elevé
Plus l’urine est dilué plus la GS est bas
La GS dépend des tubules
Hématurie
Globules rouges ou hémoglobine
Gloubules rouges proviennent du rein
uretère, véssie ou prostate
> 5 méritent une investigation
Leucocytes
Pyurie
proviennent du rein, uretère, véssie,
prostate, ou urèthre
Cystite
Peuvent etre assures sans investigation
Bactéries
Dénotent inflammation
Infection (cystite, pyelonéphrite)
Néphrite interstitielle
– Medicaments, réaction allergique
Asymptomatique ou symptomatique
Accompagnées de globules blancs
Cylindres (casts)
Sont des ‘empreintes’ des tubules
Proviennent des reins
D’importance variée
Bénins: hyalines, granulaires en petite
quantité
Pathologies importantes: granulaires en
grande quantité, RBC casts
Protein comes in many sizes
Size is described in ‘molecular weight’
Low molecular weight (small)
– Light chains
Medium molecular weight (medium)
– Need an example
High molecular weight (large)
– albumin
How does kidney handle protein?
Filters
Reabsorbs
Minimally excretes
Urinary protein
Some protein is normal!
– 150 mgs in 24 hours
» 10-15 mgs is albumin
» Small sized plasma proteins
» Pieces of renal cells
‘Proteinuria’ is an abnormal amount of
protein in urine,
– ie > 150 mgs in 24hrs.
Detecting protein in urine
Dipstick (used in physician offices)
– Trace, 1+, 2+, 3+
» False positive situations exist
High specific gravity (very concentrated urine)
Very alkaline urine
» False negative situations exist
Very low specific gravity (very dilute urine)
Rule of thumb
– Protein level (mgs %) should not exceed SG (last 2 digits)
» Eg if SG is 1.022, protein should be < 22 mgs%
» If SG 1.30 protein should be < 30 mgs%
(IV) MEASURING PROTEINURIA
Semiqualitative
(Dipstix)
Quantitative
Trace
1+
2+
3+
4+
10 - 30 mg/dL
31 - 50 mg/dL
51 - 125 mg/dL
126 - 300 mg/dL
301 mg/dL & up
Detecting protein in urine (2)
Quantitative
– Spot measurement- usually recorded in mgs%
or mmol/L
– 24 hour urine collection
» Measure protein and creatinine
Cumbersome, inconsistent and unreliable
< 1G creatinine excreted: likely an incomplete collection
PROTEINURIA (INSURANCE POPULATION)
viz. 60% of cases of increased
protein in urine in insurance
population = due to increased
albumin
Contaminants
<1% Paraproteins
Albumin
Sloughed Renal Cells
RBCs, WBCs
Detecting protein in urine (3)
protein/ creatinine ratio
– Independent of specific gravity or urinary
volumes
– > 0.2mgs/ G creatinine is abnormal
» 0.2-1.5 suggests tubular disease
» > 1.5 suggests glomerular disease
Detecting protein in urine (4)
Albumin/creatinine ratio
– Proteinuria may be due to non-renal sources
» Prostate, vaginal. RBC’s WBC’s
– albuminuria is specific for renal disease
» < 30mgs / 24 hours is N (< 3 mgs%)
» ‘Microalbuminuria’ is 30-300 mg/24h. (3-30mgs%)
» ‘Macroalbuminuria’ is > 300 mg/24h. (> 30mgs%)
– Albumin/ creatinine ratio > 0.3 is abnormal
Measuring urinary albumin
Albumin Alb/creat Alb/creat 24h. urine
(mgs/dl) (mgs/G) mgs/mmol albumin
(mgs)
Normal
<3
< 30
< 2.5
< 30
Microalb
< 30
30-300
2.5-25
30-300
Macroalb
> 30
> 300
> 25
> 300
Why measure albumin in urine?
Better index of glomerular disease
As glomerular disease progresses
albuminuria appears first. This is called
‘microalbuminuria’
As amount of albumin increases we use the
term ‘macroalbuminuria’ or ‘proteinuria’ (as
dipstick for protein is now positive)
Benign proteinurias
Intermittent proteinuria
Postural or ‘orthostatic’
– N supine; elevated when upright
Exercise-induced
Febrile illnesses
Contaminants: seminal, prostatic, vaginal
fluids
Pathologic proteinurias
Constant proteinurias
– > 1/3 specimens (insurance)
– > 3 months duration (clinical)
Albuminuria
– Microalbuminuria
– Macroalbuminuria
Bence-Jones proteinuria
Don’t jump to conclusions!
Albumin levels vary
– posture, exercise, fever, other
Creatinine levels vary
– Handling delays reduce urine creatinine
– creatinine production decreases with
» Increasing age
» Older women in particular
50% of abnormal results will be normal with retesting!
Significant proteinuias
Glomerular
– Glomerulus is ‘leaky’
– Too many proteins are making way into tubule
Tubular
– Tubules are not reabsorbing
overflow
– Capacity of tubules to reabsorb is overwhelmed
– Tubules are working normally
structure of glomerulus
arteriole
collecting duct
to bladder
normal glomerulus