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