The Importance of Proteinuria

Question 1

When do we test for proteinuria?

Answer 1

-Any routine medical consultation
=Asymptomatic medical assessment is cheap, non-invasive, reliable and alters management
-Oedema (caused by low level of protein in blood)
=Periorbital, sacral (if recumbent), unexplained ascites or pleural effusions
-As part of care of patients with hypertension, diabetes mellitus
-If a systemic disease is possible

Question 2

How can we observe protein in the urine without tests?

Answer 2

• Frothy (protein acts as detergent so forms bubbles when shaken)
• Protein forms white precipitate when boiled

Question 3

Describe a positive proteinuria result and next steps

Answer 3

-2+ or more implies intrinsic renal disease, very unlikely to be explained to asymptomatic infection
=up to 4+
-Quantify albumin: creatinine ratio (timed collection rarely helpful, creatinine constant and corrects for urine concentration)
-Test kidney renal function, consider systemic disease
-Never ignore

Question 4

What is not the correct response to a finding of proteinuria?

Answer 4

Send an MSU to exclude infection

Question 5

Describe albuminuria

Answer 5

-Albumin: creatinine ratio (mg/mmol) can be performed on small urine sample taken at any time of the day
-ACR x 10 approximates to mg/24hrs (renal disease= 100 reflects 1g/24h)
-Normal ACR less than 3.5
=3.5-30 microalbuminuria
=>30 macro albuminuria

Question 6

What are the measurements of excretory renal function?

Answer 6

• Plasma/ serum creatinine
• Estimated GFR: MDRD formula (sex, age, race, creatinine)- UV/P
• Creatinine clearance
• Isotope GFR (usually 51Cr EDTA)

Question 7

What is the difference between plasma and serum?

Answer 7

Plasma is the watery part of the blood without cells while serum is the plasma without the clotting factors

Question 8

Where in the kidney is vulnerable to atherosclerosis?

Answer 8

-Renal artery origin because of turbulence

Question 9

How does number of nephrons vary in the population?

Answer 9

• Healthy young adult Caucasoid have approx. 1 million nephrons
• Black and Asian people may have fewer nephrons
• Number of functioning nephrons decrease with age

Question 10

What are the layers of the glomerulus?

Answer 10

• Podocytes (primary and secondary processes)
• Glomerular Basement Membrane
• Glomerular Endothelium

Question 11

What causes Congenital Nephrotic Syndrome?

Answer 11

-Mutation in podocyte-specific gene (Nephrin)

=protein leaks freely into urine

Question 12

What are the next steps when a result positive for protein and blood in the urine comes back?

Answer 12

• BP
• Test for diabetes
• Quantify proteinuria
• Check kidney function
• Renal ultrasound
• Renal biopsy

Question 13

What does presence of blood and protein in urine imply?

Answer 13

-Glomerular disease
=urgent test excretory kidney function
=consider systemic disease such as vasculitis and lupus

Question 14

What does albuminuria indicate?

Answer 14

• In diabetes mellitus, microalbuminuria is the earliest clinical feature of diabetic nephropathy; may be initially intermittent
• In hypertension, albuminuria suggests primary renal cause
• In all patients, including in the absence of diabetes or hypertension, albuminuria carries prognostic significance
• microalbuminuria risk factor for cardiovascular events

Question 15

What are the next steps when there is lots of protein and no blood in the urine?

Answer 15

-BP
-Test for diabetes/other systemic diseases
-Quantify
proteinuria
-Check kidney function
-Renal ultrasound
-Renal biopsy
-Treatment (corticosteroids, other drugs)

Question 16

Describe Nephrotic Syndrome

Answer 16

• Clinical syndrome comprising oedema, heavy proteinuria, Hypoalbuminaemia
• Not included in the definition, but often clinically important are thrombotic risk, propensity to infection and often severe hyperlipidaemia
• May or may bot be associated with impairment of excretory kidney function
• Dominant symptoms often severe lethargy, reduced exercise tolerance, nausea, loss of appetite
• Causes include glomerular nephritis, diabetes, infection (hepatitis B/C, malaria, HIV), amyloid

Question 17

What haematuria be a sign of (blood in urine)?

Answer 17

-Serious systemic disease for which diagnosis and treatment is very urgent, whether or not there is also albuminuria
=vasculitis (eosinophilic?)
-Blood test
=Anti-neutrophil cytoplasm antibody (ANCA)

Question 18

Examples of disease where the glomerulus is damaged (proteinuria/ haematuria)

Answer 18

• Rare genetic/ developmental disorders
• Diabetes mellitus
• Vascular disease/ ischaemia/ age
• Inflammation of blood vessels “vasculitis)
• Inflammation of glomerulus itself (glomerulonephritis, various types)
• Deposition disease (amyloid, myeloma)