Differential Diagnosis of Proteinuria:
I. Functional proteinuria:
There is no organic change in the kidney tissue: it is usually less
than 1 gm/d and is reversible. Possibly, it is due to hemodynamic changes
or to minor glomerular disease which are reversible.
a. Strenuous exercise
b. Fever
c. Orthostatic proteinuria
d. Miscellaneous
(Thyrotoxicosis, severe anaemia, CNS lesions)
II. Patients with proteinuria of 0.5-3.5 gm/d:
a. Acute interstitial nephritis.
b. Chronic interstitial nephritis such as bacterial (pyelonephritis), gouty
nephropathy, analgesic nephropathy or nephrolithiasis.
c. Tubular proteinuria such as Fanconi syndrome, heavy metal
intoxication (lead, cadmium), multiple myeloma, hypokalaemic
nephropathy, polycystic kidney disease and medullary cystic kidney
disease.III. Patients with proteinuria of more than 3.5 gm/d:
Usually caused by glomerular disease.
a. Primary glomerular disease: refers to all types previously
discussed under glomerulonephritis.
b. Secondary glomerular disease is Previously discussed under
glomerulonephritis.