Cysteine 18 should refer to homocysteine 18 μmol/L, which is a mild elevation and not considered severely elevated. Clinically, the normal value of homocysteine in human body is 5~15μmol/L, more than this range we can call homocysteine elevation, but homocysteine 18μmol/L does not exceed the normal value to a greater extent, so it belongs to the mild elevation. Elevated homocysteine is usually seen in diseases such as folic acid deficiency, renal insufficiency, hypothyroidism, and unhealthy dietary lifestyles. When abnormal homocysteine is detected, you should consult a medical professional for better advice on diagnosis and treatment. In summary, homocysteine 18 μmol/L is a mild, not particularly serious elevation. However, this group of people needs to have the help of professional advice, so it is also important to consult a doctor when such a situation arises.