Emergent Cardiovascular Risk Factor: Homocysteine

Cindy J. Warren, MSN, RN


Prog Cardiovasc Nurs. 2002;17(1) 

In This Article

Abstract and Introduction

Homocysteine is an independent, modifiable risk factor for cardiovascular disease. It is an intermediate amino acid formed during the metabolism of methionine. Plasma homocysteine is normally ≤12 µmol/L, but when elevated has many deleterious cardiovascular effects. This review explains homocysteine metabolism, the effects of elevated homocysteine, factors contributing to high homocysteine, and its measurement. Risk factors for elevated homocysteine and intervention with B vitamins are discussed. Cardiovascular nurses are encouraged to facilitate homocysteine awareness through a variety of educational means.

In 1969 Dr. Kilmer McCully, a Harvard Medical School graduate, proposed the relationship between homocysteine and coronary artery disease. His work did not gain acceptance until recently.[1] Now, research demonstrates that homocysteine is an independent, modifiable risk factor for cardiovascular disease[2,3,4,5,6] and a strong predictor of mortality in patients with coronary artery disease.[6] Some studies have found hyperhomocysteinemia to be a higher risk factor for coronary artery disease than hypercholesterolemia or smoking[3] and that high homocysteine powerfully increases the risk of vascular disease when combined with smoking and hypertension.[6] Other studies have shown no relationship between plasma homocysteine and serum cholesterol.[3] Even though homocysteine research is still in progress, many researchers agree that there is a clear relationship between high plasma homocysteine and many vascular diseases.[2,3,4,5,6] This review will address the practical aspects of homocysteine screening and education, as well as describe how cardiovascular nurses can collaborate with physicians, fellow registered nurses (RNs), patients, and the community to increase awareness of this modifiable risk factor. The focus is on research findings, assessment criteria, and avenues of dissemination of this information by cardiovascular nurses.

"A 57-year-old man had a family history of premature coronary artery disease (his father died of a myocardial infarction at the age of 46 years), but he had no personal history or clinical symptoms of cardiovascular disease. His weight was normal, and his blood pressure was 124/82 mm Hg. He did not smoke, and he exercised approximately twice a week. In fact, beyond his family history, he had no other known risk factors for coronary artery disease. The patient's fasting plasma lipid levels were as follows: total cholesterol, 236 mg/dL (6.10 µmol/L); low-density lipoprotein (LDL) cholesterol, 133 mg/dL (3.45 µmol/L); high-density lipoprotein cholesterol, 88 mg/dL (2.30 µmol/L); and triglycerides, 74 mg/dL (0.84 µmol/L). The fasting glucose concentration was 90 mg/dL (5.0 µmol/L). Because of the patient's family history, his total plasma homocysteine concentration was checked and was found to be 29 µmol/L (optimal value: <12 µmol/L). The patient was given a multivitamin containing 400 µg of folic acid plus an additional 400 µg of folic acid per day for 2 months. His repeat homocysteine level was less than 2 µmol/L. The patient is currently taking 400 µg of folic acid and the multivitamin each day. Follow-up homocysteine testing is performed every 8 weeks or as often as necessary to ensure that he maintains a homocysteine level in the optimal range, thereby reducing or eliminating this atherosclerotic risk factor."[4] The preceding case study illustrates the process of identification and successful treatment of the homocysteine cardiovascular risk factor.

Research has shown that most patients with myocardial infarction or carotid stenosis have normal cholesterol levels.[2,4,7,8] An autopsy study[2] found that in two thirds of cases of severe arteriosclerosis, the disease developed without evidence of elevated serum cholesterol, diabetes, or hypertension. The presence of high plasma homocysteine levels has recently been accepted as an independent atherogenic and thrombotic factor,[3,4] yet homocysteine testing and education are not routinely being done. Careful assessment of homocysteine risk factors and intervention with effective therapies may help prevent cardiovascular disease.[4,9]

Since cardiovascular nurses are the primary educators for patients, it is increasingly important that nurses' knowledge of health information is current,[10] especially when Internet access provides easily ob-tainable medical information to the public. Patients are well informed and ask important health-related questions. This review proposes that cardiovascular nurses increase their awareness of hyperhomocysteinemia by discussing recent homocysteine re-search findings with physicians and other nurses, professionals in other disciplines, patients, and the general public. In addition, the assessment screening criteria that can be used to help identify those with increased risk of hyperhomocysteinemia will be presented.


Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.