The ACE test, or Angiotensin-Converting Enzyme test, is a blood test that measures the levels of ACE in your bloodstream. ACE is an enzyme that plays a crucial role in regulating blood pressure by converting angiotensin I into angiotensin II, a potent vasoconstrictor. Monitoring ACE levels helps assess the renin-angiotensin-aldosterone system's function, a key player in blood pressure regulation.