The document provides an in-depth clinical presentation on proteinuria, defining it as excessive protein in urine, with normal levels being less than 150 mg/24 hours. It discusses types of proteinuria, testing methods, limitations of screening tests, and treatment options, emphasizing the importance of identifying underlying causes and potential referrals to a nephrologist. Key classifications include glomerular and tubular proteinuria, with respective diagnostic features and management strategies outlined.

1. Department of Chemical Pathology,
Federal Teaching Hospital Abakaliki
Clinical Presentation on:
Proteinuria
By: Dr Onu Emmanuel Mbah
Date: 11 Feb. 2016
Supervising Consultant: Dr Okeke NJ

2. Outline
• Introduction
• Classification of proteinuria
• Testing for proteinuria
• Limitation of screening tests
• Investigating a patient with proteinuria
• Appreciation
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3. Introduction
• Proteinuria is defined as the presence of
excessive proteins in the urine.
• Normal urinary protein excretion is < 150 mg/24
hour, mostly alb. and then Tamm-Horsfall protein
• Daily albumin excretion in a normal person is < 30
mg.
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4. .
• UAER averages 2.6-12.6 µg/min in males and 1.1-
21.9 µg/min in females.
• Microalbuminuria is referred to as the excretion of
30-300 mg of albumin daily or 20-200 µg of
albumin per minute.
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5. .
• The glomerular basement membrane (GBM) acts
as an ultrafilter for plasma proteins
• The ability of individual proteins to pass through
the membrane is a function of:
• (1) molecular size
• (2) net ionic charge
• (3) plasma concentration of the proteins.
• Transport of protein molecules through the
glomerular membrane is inversely related to size
and net negative charge.
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6. .
• Significant amount of Albumin (64 kDa) is passed
into the filtrate as a result of its high plasma
concentration and relatively low molecular mass.
• Proteins with molecular masses of 15 to 40
kDa filter more readily but in lesser quantities
because of their low plasma concentrations.
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7. Classification of Proteinuria
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8. Tubular Proteinuria
• Tubular proteinuria occurs most commonly in
tubulo-interstitial diseases of the kidney
• It comprises low molecular proteins such as beta-2
microglobulin, which in normal conditions are
completely reabsorbed by proximal tubules.
• The amount of proteinuria is < 2 g and dipstick may
be negative.
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9. .
• Agarose electrophoresis of urine gives a
characteristic pattern-prominent a- and P-bands,
a relatively faint albumin band, and sometimes
a post-yband.
• Sodium dodecyl sulfate polyacrylamide gel
electrophoresis (SDS-PAGE) is more useful in
detecting tubular proteinuria in the presence of
glomerular proteinuria as it separates proteins by
molecular size.
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10. .
• Acute tubular proteinuria complely reversible
• May occur in:
• (1) burns,
• (2) acute pancreatitis,
• (3) heavy metal poisoning,
• (4) administration of renotoxic drugs
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11. .
• Chronic tubular proteinuria is usually irreversible, may
be severe
• Causes:
• Hereditary, as in Fanconi syndrome
• Acquired:- localized dz e.g chronic pyelonephritis -
systemic disease, e.gs cirrhosis, sarcoidosis.
• drugs, e.g phenacetin
• toxins e.g cadmium
• Diminished or diminishing tubular reabsorption is
suggested by increasing concentrations of low
molecular mass proteins in urine.
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12. Glomerular Proteinuria
• This is the most common and serious type of
proteinuria.
• Patients are routinely screened for this disorder
by a simple diptick test for albumin.
• If the dipstick test result is negative, clinically
significant glomerular proteinuria is precluded.
• Because most of the excreted protein is albumin,
glomerular proteinuria is often termed albuminuria
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13. Classification of Glomerular
Proteinuria
• Pathological
• Nephrotic/overt
• Non-nephrotic
• Functional/benign
• Transient proteinuria
• Orthostatic proteinuria
• Functional proteinuria is seen in (1) exercise, (2)
pyrexia, (3) exposure to cold, (4) congestive heart
failure, (5) hyperten- sion, and (6) arteriosclerosis.
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14. Transient Proteinuria
• Occurs in patients with normal renal function, bland
urine sediment, and normal BP
• The quantitative protein excretion is less than 1 g/day.
• The proteinuria is not indicative of significant
underlying renal disease
• It may be precipitated by high fever or heavy exercise
• It disappears upon repeat testing.
• In normal pregnancy, protein excretion may increase
harmlessly to 200 to 300 mg/d.
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15. Orthostatic Proteinuria
• Postural or orthostatic proteinuria is associated
with the upright position
• Here the patient has no proteinuria in early morning
samples but has low-grade proteinuria at the end of
the day.
• It usually occurs in tall, thin adolescents or adults
younger than 30 years (and may be associated with
severe lordosis).
• Patients have normal renal function and proteinuria
usually is less than 1 g/day with no hematuria
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16. .
• In non-nephrotic proteinuria, the amount of
proteinuria is < 3.5 g/24 h and is persistent
• It can occur in preeclampsia
• Nephrotic-range proteinuria is defined as >3.5 g of
proteinuria on a spot urine protein–to-creatinine
ratio and denotes significant glomerular disease
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17. Overflow Proteinuria
• Occurs when proteins are produced in amounts
greater than the reabsorptive capacity of the
proximal tubule.
• It includes (1) hemoglobinuria, (2)myoglobinuria,
and (3) Bence Jones proteinuria
• These low molecular proteins can be toxic to the
tubules and can cause acute kidney injury.
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18. Testing for Urinary Protein
• Fresh sample should be used
• Screening test involves dipstick test e.g with
albustix (with tetrabromophenol blue)
• Albustix is buffered to PH 3; normally yellow
• It turns green or bluish-green if protein is
present.
• The colour is then matched on a chat to indicate
the protein conc.
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19. Limitations of Screening Tests
• The tests were mainly developed to detect albumin
and may be negative in the presence of other
proteins, such as BJP.
• Because the tests depend on protein
concentrations, very dilute urine may give negative
results despite significant proteinuria.
• False-negative results occur if acid has been
added to the urine as a preservative
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20. .
• False-positive results occur:
• if the specimen is contaminated with vaginal or
urethral secretions, including haematuria, semen or
menstrual fluid,
• in strongly alkaline (infected or stale) urine, when
buffering capacity is exceeded; a green colour in this
case is a reflection of the alkaline pH,
• if the urine container is contaminated with
disinfectants such as chlorhexidine.
• Spot urine ACR or P:C ratio (in pregnancy) is more
convenient. (P:C in mg/mmol; ACR in g/d)
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21. .
Investigationofapatientwith
proteinuria
Fig.adaptedfromClinicalBiochemistryandMetabolicmedicine18thed.byMartinCrook
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22. Treatment
• Nonspecific treatment - Treatment that is
applicable irrespective of the underlying cause.
• Specific treatment - Treatment that depends on the
underlying renal or nonrenal cause
• The patient is referred to a nephrologiste esp. if
bad prognostic indecis are observed eg albuminuria
> 1g/d, or worsening renal funxn
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23. • Use of ACEIs or ARBs
• Target blood pressure is less than 125/75 mm Hg.
• The dose of ACE inhibitor should be increased as
tolerated until this blood pressure is achieved.
• Normotensive patients with proteinuria also should
be given ACEIs.
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24. • Diuretics
• Patients with moderate to severe proteinuria are
usually fluid overloaded and require diuretic
therapy along with dietary salt restriction.
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25. Appreciation
Thanks for Listening
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