The document provides an in-depth approach to diagnosing and managing proteinuria, outlining definitions, types, and causes of proteinuria along with quantitative and qualitative testing methods. It discusses benign proteinuria, clinical examinations, laboratory tests, and algorithmic approaches for referrals to nephrologists based on specific patient criteria. Key take-home messages emphasize the importance of urine dipstick screening, further assays for significant proteinuria, and when to consider nephrological referrals.

1. APPROACH TO PROTEINURIA
TRAN MINH HOANG, M.D.
Pham Ngoc Thach University of Medicine
Ho Chi Minh city, Viet Nam
bacsitranminhhoang@gmail.com

2. Content
Quantitative and qualitative assays of
urine protein
Causes of proteinuria
Approach to proteinuria
1
2
3

3. Physiological urine protein
Tamm-Horsfall protein Blood group related antigen
Albumin Mucopolysaccharide
Immunoglobulins Hormones and enzymes
Urine protein < 150 mg/day
Urine albumin < 30 mg/day
Children : urine protein < 4 mg/m2 /hr or < 100 mg/m2 /24hr

4. Definition
• Proteinuria
– Urinary protein excretion > 150 mg/24h
• Albuminuria
– Urinary albumin excretion > 30 mg/24h

5. Quantitative urine protein test
Urine Dipstick 24 hour urine protein
Protein – Creatinine Ratio
Trace + ++ +++ ++++

6. Urine protein tests
PER (mg/24h) 150 500
PCR (mg/g)
(mg/mmol)
150
15
500
50
AER (mg/24h) 30 300
ACR (mg/g)
(mg/mmol)
30
3
300
30
Protein/Urinalysis - trace 1+ 2+,3+ 4+
Creatinine excretion rate ~ 10 mmol/day ~ 1 g/day

7. Urine protein electrophoresis
Kowsalya R et al., J Cancer Res Ther 2015, 3(6):72-76

8. Pathological proteinuria

9. Benign proteinuria
• Transient proteinuria
• Functional proteinuria
– Dehydration
– Emotional stress
– Fever
– Heat injury
– Inflammatory process
– Intense activity
– Most acute illnesses

10. Orthostatic proteinuria
• Young < 30 yo., tall, PER < 2g/24h, normal GFR.
• Unclear mechanisms : subtle glomerular abnormalities
+ exaggerated hemodynamic response …
• Orthostatic proteinuria workup :
– Avoid strenuous exercises 24 hours before the test
– 16 hour daytime specimen obtained with pt. performing normal activities and
finishing collection just before bedtime
– 8 hour overnight specimen : urine protein < 50 mg (<4 mg/m2 per hour in
children)

11. Clinical approach
• Past medical history : systemic illnesses, arterial
hypertension, diabetes mellitus…
• Clinical examination : edema, signs of systemic
diseases (cutaneous lesions…)
• Urinary sediment : RBC casts (++), waxy cast, broad
cast, fat oval bodies, WBC cast (eosi.)
• Biological, immunologic blood and urine tests

12. Laboratory tests
• CBC, creatinin, urea, FBG, lipid panel
• Uric acid, serum electrolytes (Na+, K+, Cl-, HCO3-,
Ca2+, PO43-)
• Serum, urine protein electrophoresis
• HIV, hepatitis serologic test, VDRL
• ANA, anti-dsDNA, C3, C4, ASO, ANCA (±)
• Renal ultrasonography
• Chest radiograph

13. Algorithmic approach to proteinuria
Dipstick (+)
False positive, functionnal
proteinuria causes
Recheck Dipstick
Nephrological
referral
Trace, 1+, 2+ 3+, 4+
Repeat UA 2 - 3 times
in the next month
Transient
proteinuria
< 2g/day
Quantify proteinuria
Findings
consistent with
renal diseases
Reassure
No follow - up
> 2g/day
Age < 30 and
normal GFR
Orthostatic
proteinuria work up
Age ≥ 30 or
reduced GFR
UA, blood
pressure, creatinine
every 1 – 2 years
(-) (+)
(+) (-)

14. Nephrological approach
Nephrotic range
Pu
PER 1 – 3 g/24h
PER < 1 g/24h
Hypoalbuminemia
Glomerular hematuria
Hypertension, acutely
reduced GFR
± reduced GFR
(acute/chronic)
± uremia
Nephrotic syndrome
Nephritic syndrome
Acute kidney injury
Chronic renal failure
Follow up every 6
months : blood
pressure, UA,
creatininIsolated proteinuria
?
Normal GFR, urine sediment,
no hypertension, no diabete
Explorations
Kidney biopsy (±)

15. Question 1 : Which of the following statements
about proteinuria is TRUE?
A. The result of protein 1 (+) on Dipstick is equivalent to 1 g/l
B. The presence of the immunoglobulin light chain in urine is a
stigmata of the glomerular injury
C. Albumin is the main constituent of normal urine protein
D. A diabetic patient has renal microvascular complication if the
ACR is > 30 mg/g
E. Selective proteinuria (urine albumin proportion > 80%) in a 6
year-old child makes the diagnosis of minimal change disease
and empiric corticotherapy can be started without kidney biopsy

16. Question 2 : Who of the following patients should
be referred to a nephrologist ? (multiple answers)
A. 65-year-old man, arterial hypertension, asymptomatic,
proteinuria 2.5 g/24h, blood (-), GFR 65 ml/min/1.73m2
B. 25-year-old female patient, systemic lupus erythomatosus,
proteinuria 700 mg/24h, blood (+), GFR 95 ml/min/1.73m2
C. 30-year-old patient, 33 weeks pregnant, asymptomatic,
protein (+), blood (+), leucocyte (+)
D. 58-year-old female patient, diabetes mellitus 3 years,
ACR 35 mg/g, blood (-), GFR 35 ml/min/1.73m2

17. Take home messages
1. Screening of proteinuria : urine dipstick, ACR/AER
2. Quantitative and qualitative urine protein assay in case of significant
Pu ≥ 2+/Dipstick: PER 24h, PCR, urine electrophoresis
3. Mild proteinuria (0.2 – 2g/24h) : need to think of transient proteinuria,
orthostatic proteinuria, isolated proteinuria…
4. Moderate – severe proteinuria (>2g/24h) : presence or absence of
active urine sediment, GFR ?...
5. Nephrological referral : non-nephrotic range proteinuria of unknown
cause, nephrotic range proteinuria, active urine sediment, renal failure.

18. THANK YOU FOR YOUR ATTENTION