1. Evaluation of Proteinuria
Craig Dobson, MD
CPT, MC, USAR
NCC Pediatrics

2. What is proteinuria, baby?
Some degree is always present.
Tamm-Horstfeld Proteins are actually secreted by tubules themselves.
Urine dipstick is extremely sensitive
Normal 24hr Protein output
< 200mg/dL for adults.
< 20mg/kg/day for children
Spot protein detection must always be interpreted in the context of concentration of urine.
1+ Protein SG is not concerning.
1+ SG may be important.
Other renal signs, especially edema, should lead you to believe the result more.

3. False Postives for UA Protein
pH > 8
Hematuria
Leukouria (incl. UTI)
Fever
Not really a false positive.
Causes leaky basement membrane.
Chlorhexidine wash to clean perineum.
Vaginal/seminal secretions
Menstrual blood
Exercise
Concentration

4. How do we achieve a better estimation of quantity of proteinuria?
Spot Urine Protein/Creatinine Ratio
Normal <0.3 for children over age two.
Normal <0.5 under age two.
Well validated/nearly equivalent to 24hr Urine.
24hr Urine Collection
Very difficult in children.
Usually performed incorrectly.
Many peds nephrologists only use Prot/Cr.

5. Causes of Proteinuria Orthostatic Proteinuria Pathogenesis
Extremely common. Incidence 7-12% of adults.
Pathogenesis
Now proven to be laxity of support to kidney allows kidney to fall slightly when standing.
Kinking of renal vein occurs.
Back pressure causes minor spillage of protein.
Absolutely a benign condition!
No renal impairment/failure associated with it.

6. Other causes of Proteinuria
Glomerular
Glomerulonephritis
Refers to any inflammation of glomerulus.
Should have glomerular hematuria (RBC casts, abnormal shaped RBCs in urine)
Minimal change disease
IgA nephropathy
Also should have RBCs.
Tubular
Acute Tubular Necrosis
Fanconi’s Sx.
Lowe’s Syndrome
Cystinuria
High Plasma Proteins
Myoglobinuria/Hemoglobinuria
Leukemia
Urinary Tract
Tumor
Inflammation

7. Evaluation of Isolated Proteinuria
First r/o orthostatic proteinuria
First morning void after lying recumbant for at least 6hrs. (Also rules out exercise as a factor.)
Urine Protein/Creatinine ratio
If >0.2, proceed to further work-up
Referral to Nephro if >0.2
Labs
BUN, Cr, C3, ASO, ANA
Consider Hep B/C, HIV
Imaging
Consider renal U/S.

8. Nephrotic syndrome
Refers to the degree of proteinuria, not a disease by itself.
Prot/Cr ratio is significant proteinuria.
>=2.5 is nephrotic range.
Equivalent to 2.5g/day in adult.
May be caused by any of the causes of proteinuria including nephritis.
Most common cause is minimal change disease.
Treatment is trial of steroids
Renal biopsy for failure to respond to steroids.