A 41 yeаr-оld mаn is аdmitted tо the hоspital complaining of a decreased frequency of urination, a constant bloated feeling, weight gain, and mild edema of the ankles and eyes. Urinalysis results are as follows: Color: Yellow MICROSCOPIC RESULTS Clarity slightly cloudy RBCs: 2-5 pH: 5.0 WBCs: 0-2 Specific gravity: 1.015 Casts: 2-5 hyaline; 0-3 fatty casts; 0-2 waxy casts Glucose: 2+ Few transitional Epithelial Cells Ketones: Negative Few Oval Fat Bodies Protein: 3+ Blood: Trace Bilirubin: Negative LE: Negative Urobilinogen: Normal Nitrite: Negative ** A large amount of white foam was noted Based on the urinalysis report above, the MOST probable diagnosis is: