Plaquenil isn't indicated for organ involvement. However it is a general disease modifying agent with numerous useful side benefits and many people who need additional drugs stay on it and remain on it after the more severe forms of disease have been treated successfully. Plaquenil is a first oral medicine and a basic medicine but there's probably not much point adding it as this stage. Later it could be worth starting it later as a sort of "guarantee" or help to keeping disease stable.
The drugs most often added for organ involvement are the immunosuppressants, Imuran/azathioprine and Cellcept or/ and Cytoxan, along with Prednisone, as needed and depending on response.
I'm sorry you have the kidney disease to deal with and hope it can be quickly brought under control
Though Plaquenil is not used as a treatment for kidney involvement, I did read an article on the Lupus Foundation of America website that says: [source link - see #5]
"Clinical research data released in 2008 showed that lupus patients treated with hydroxychloroquine, used most often to treat lupus skin and joint problems, were less likely to have kidney disease, had less severe disease, and required lower doses of corticosteroids than patients who did not receive the drug."
So even though Plaquenil won't treat your kidneys if you're having problems, it seems like a good line of defense for controlling the overall disease activity, like Clare said (I think she said it better than I did, lol).