What Causes Constant Foamy Urine?

DEAR DOCT.

I AM WRITING ON BEHALF OF MY SON AGED 21.FROM HIS TEENS WE OBSERVED THAT HIS URINE IS VERY FOAMY. SOME 4YEARS BACK,HE FELL DOWN WITH FEVER WHEN THE GP ADVISED FOR BLOOD TEST FOR TC,DC,ESR & URINE FOR ROUTINE & CULTURE. THE TEST REVEALED TC COUNT WITH 88 NUTROPHIL COUNT. ROUTINE URINE SHOWED ++++ALBUMIN WITH PLENTY COUNTS OF RBC& PUS CELLS. FEVER WAS ASSOCIATED WITH SYNDROM OF PNEUMONIA.STRONG IV ANTI-BIOTICS WERE ADMINISTERED AND DIRUTICS USED TO PREVENT FLUID RETENTION. THERE WAS NO SWELLING ANY WHERE.USG OF WHOLE ABDOMEN SHOWED NORMAL READINGS.ANCA,ANF SHOED NA.HOWEVER HIS BP WAS A BIT HIGH .AFTER 7 DAYS FEVER AND COUGH SUBSIDED BUT FOAMY URINE CONTINUES WITH INTERMITTEN TESTS SHOWING ++,+ORTRACE.NOW IT IS TRACE AND CULTURE AT ON POINT SHOWED ANY GROWTH.24HR. PROTEIN URINE TEST WHICH WAS AT THE BEGINING WAS935 NOW STAYING WITHIN 345 TO 538. HE IS NOW ON LOSARTAN 50MG OD FOR LAST2 YEARS. BP IS ABSOLUTELY NORMAL BUT URINE IS FOAMY. IT INCREASES WITH ANY SORT OF INFECTION AND THEN DECREASES BUT NEVER BECOMES NIL REPORT OF URINE TEST.DOCTOR SAYS IT IS IGID . PLEASE ADVICE WHETHER THE TREARMENT AND DIAGNOSIS IS CORRECT AND WHETHER YOU SUGGEST ANY OTHER MEDICINE OR TESTS.