Laboratory for Molecular Diagnostics
Center for Nephrology and Metabolic Disorders

Proteinuria

Urinary protein excretion greater than 150mg/day is considered proteinuria.

Clinical Findings

Proteinuria is the leading symptom of the nephrotic syndrome, which includes peripheral oedema due to low serum protein levels. Hypertension and haematuria my be present but are not the leading symptoms as in nephritic syndrome.

Classification

Molecular weight allows to distinguish glomerular and tubular proteinuria. The latter is also known as low molecular weight proteinuria. The former may be further divided into selective and unselective glomerular proteinuria. Pathological proteins, such as Bence Jones protein, happen in urine in the course diseases with protein overproduction.

Microalbuminuria is a highly slective glomerular proteinuria with virtually only traces of albumine excretion (30-300mg/d).

Staging

Dip sticks allow to measure proteinuria semiquatitatively:
traces 15-30mg/dL,
1+ 30-100mg/dL,
2+ 100-300mg/dL,
3+ 300-1000mg/dL,
4+ >1000mg/dL.
Nephrotic range proteinuria is above 3500mg/day.

Diseases

Alport Syndrome
Proteinuria is seldom the leading symptom in Alport syndrome. It usually occurs after hematuria and almost never reaches nephrotic range.
CFHR5 Nephropathy
Proteinuria becomes apparent in young adults often accompanied by hypertension.
Congenital nephrotic syndrome type 10
Proteinurie often develops into nephrotic range, it response to immunosuppressive therapy, but often relapses.
Dent disease
Proteinuria is an early symptom. It is the most consistent symptom and detected in obligate female carriers even. Typically at the beginning, it is a low-molecular-weight (tubular) proteinuria (LMWP) that pattern may change however with disease progression.
Diabetes mellitus
Microalbuminuria is an early symptom of renal damage in diabetes mellitus. In severe diabetic nephropathy proteinuria can reach the nephrotic range.
Fibronectin glomerulopathy
Proteinuria is the first symptom in patients with fibronectin glomerulopathy.
Hereditary FSGS type 6
Proteinuria in FSGS6 is usually nephrotic.
Hereditary FSGS type 7
Proteinuria, which may reach nephrotic range, is an important feature of FSGS caused by mutations of the PAX2 gene.
Congenital nephrotic syndrome type 04
Proteinuria in NPHS4 is accompanied by mesangial sclerosis and possibly abnormalities of sexual organ development.
Nephrotic syndrome
All subtypes of congenital nephrotic syndrome are characterized by mostly nephrotic range (more than 3,5g/d) proteinuria.
Renal tubular acidosis with arthrogryposis
Proteinuria pattern in ARC syndrome indicates glomerular in addition to the pathognomonic tubular damage.
ATTR amyloidosis
Proteinuria might be only mild but signals renal involvement.
Update: June 23, 2016