[@어그로입니다]
미국 NIH(http://www.nlm.nih.gov)에 따르면 Renin은
"An enzyme which is secreted by the KIDNEY and is formed from prorenin in plasma and kidney."
enzyme, 즉 효소라고 해놨네요
비교를 위해 "adrenaline"은
"Adrenaline, also known as epinephrine, is a hormone and medication which is involved in regulating visceral functions (e.g., respiration)."
hormone , 호르몬이라고 적어놓은거봐선 효소가 맞는거 같네요