Which statement about the combining forms ren/o and nephr/o is correct?

• A. Ren/o and nephr/o both mean kidney and are interchangeable
• B. Ren/o and nephr/o both mean liver
• C. Ren/o and nephr/o are not used together in any term
• D. Ren/o and nephro- are prefixes for kidney but are not interchangeable

Answer: (A)

Both ren/o and nephr/o mean kidney, and they’re interchangeable in medical terms. The choice between them comes down to established usage and smooth pronunciation in a given word, not a difference in meaning. You’ll see ren/o in words like renal and renin, and nephr/o in nephrology, nephron, and nephritis, all referring to the kidney. The other statements misstate the meaning or how these forms are used: they do not refer to liver, and they are not correctly described as one being a non-interchangeable prefix.