In general, the history is the same as the history for hematuria. Here are a few specific points.

Has the parent ever noted the child to be puffy around the face, the abdomen to be protuberant or the feet or legs to be swollen?

Edema associated with proteinuria would indicate a significant degree of proteinuria or decreased filtration of salt and water.

Has the urine ever appeared red, coke, tea or rust colored?

Hematuria accompanying the proteinuria is usually indicative of glomerulonephritis.

Has the parent ever noted the urine to be exceptionally frothy?

Heavy proteinuria can give a frothy appearance to the urine.

Has the patient ever been noted to be hypertensive?

Hypertension and proteinuria are indicative of glomerulonephritis. To this add hematuria and azotemia and the chance of progressive renal disease increases significantly.

Are there signs or symptoms of systemic disease present?

Joint pain, a rash, and fever could indicate lupus. A petechial rash on the lower extremities, abdominal pain, and joint pain could indicate Henoch-Schönlein purpura.