Returning domain object and flag from stored procedure using nhibernate

I have some problems with stored procedures (sp) and nhibernate. I want to map from the sp return values ​​a part to a domain object (already mapped via hbm.xml) and another part with a flag variable. What's the best way to do this? without casting objects? As a solution, I was trying to add a property value to a domain object named "status" and try to map that property in the returned property ... of the sql query to sp.