'nephritis-causing' is a modern compound formed from 'nephritis' (from Greek 'nephros', where 'nephros' meant 'kidney', plus the suffix '-itis' meaning 'inflammation') and English 'cause' (from Latin 'causa', meaning 'reason' or 'cause').

'nephritis' came into English via Late Latin/Medieval Latin 'nephritis' ultimately from Greek 'nephros' + '-itis'; 'cause' comes from Latin 'causa' via Old French and Middle English. The compound 'nephritis-causing' is a contemporary English formation combining these elements to describe something that produces nephritis.

The components originally denoted 'kidney' and 'inflammation' (nephros + -itis) and 'reason/cause' (causa); combined in modern usage they convey the sense 'producing kidney inflammation' (i.e., causing nephritis).