As the test is performed on the urine sample. It is essential to prevent contamination of the sample with microorganisms naturally present on the skin. During urine collection, women should spread the labia (outer lips of the vagina) while men should retract or pull back the foreskin (fold of skin covering the glans or head of the penis). Start urinating normally and let some urine flow before collecting 20 to 30 ml urine the sterilized container available from the lab or any pharmacy. After collecting the sample, finish urinating into the toilet or urinal. This process is called midstream clean catch method. The urine sample may also be collected using a catheter inserted through the urethra directly into the urinary bladder. Sample collected through a catheter usually has no contamination.

Proteinuria may be associated with diseases or conditions such as urinary tract infection, lupus, preeclampsia in pregnant women, hypertension, multiple myeloma, amyloidosis, bladder cancer, congestive heart failure, diabetes, therapies toxic to kidneys, heavy metal syndrome, and Goodpasture syndrome.