It would depend on what the cause of the proteinuria is. There are some infections that can lead to protein in the urine, and in these cases, you may want to be tested for transmissable diseases first.
Various kidney diseases can also lead to proteinuria - if that is the case, I am not aware of a connection between worsening of kidney disease and intercourse.
You may want to discuss this with your personal physician.
Followup with your personal physician is essential.
This answer is not intended as and does not substitute for medical advice - the information presented is for patient education only. Please see your personal physician for further evaluation of your individual case.
Kevin, M.D.
Medical Weblog:
kevinmd_b