Hello,
Urine dipsticks are not very good at quantitating protein levels. I would suggest instead having an albumin to creatinine ratio or protein to creatinine ratio done on a spot urine. Alternatively you could have a 24 hour urine collection for protein but usually a ratio on a spot urine will suffice. Having said that, if your blood pressure tends to be high you are on only a very modest dose of losartan and you and your healthcare provider might consider increasing the dose towards 100 mg which will also have, independently, a favourable affect on your protein levels. Patients who have had nephrectomy are susceptible to spilling protein in the urine likely due to a phenomenon of hyperfiltration which is particularly an issue in those patients who have hypertension as well. If losartan alone is an able to control your blood pressure to target levels, you might need a second medication added.
It would also be important to know what your kidney function and electrolytes are, so if you have that information we can be more precise in understanding your particular case.
I can only base my opinion on the information provided and your health-care provider might arrive at different conclusions once you have provided an entire history and had a physical examination performed. As always, this forum provides general medical information only and is limited to educational use only. Please discuss the above remarks with your health-care provider.