Hello,
Treatment of Lupus is mainly symptomatic in the initial stages, and when complication arises it should be treated.
Probably your Doctor has suggested a drug called ACE inhibitor (Enalapril/Lisinopril) etc which lowers the blood pressure and also takes the load of the Kidney.Even though this a blood pressure medication, it is also very useful in many other conditions like Lupus, heart disease etc. Here the action is not to just reduce blood pressure, but there are additive action also.
So I feel there should be some particular reason your Doctor prescribed you the medication (which is not evident in your query) and you should take it.
Hope this helps.