Homocysteine 23 μmol/L at age 65 is not normal. The normal range for homocysteine is generally between 5 μmol/L and 15 μmol/L. If it exceeds 15 μmol/L, it is considered hyperhomocysteinemia. For homocysteine at 23 μmol/L, it is in the category of mild hyperhomocysteinemia. Elevated homocysteine is mainly caused by the deficiency of B vitamins such as vitamin B6, folic acid, vitamin B12, etc. In addition, diseases such as hypothyroidism, renal diseases, psoriasis, malignant tumors, etc., or the taking of medicines such as methotrexate, nicotinic acid, antiepileptic drugs, diuretics, etc., or a large number of cigarettes, alcohol, coffee drinking, etc., can also elevate homocysteine. When homocysteine is found to be greater than 15 μmol/L, it is recommended to consult a doctor in time, improve the relevant examination with the help of a doctor to clarify the cause of the disease and target treatment.