Most people have their blood pressure, heart rate, lipid profile, fasting blood sugar, and even vitamin D levels measured during their yearly physical. Your physician may do an EKG or a stress test. All of these tests may be "normal," but there are other significant risk factors for metabolic issues that contribute to cardiovascular disease, that may be completely missed unless more testing is done.
Below is a list of some easily run lab tests and calculations which give insight into risk for insulin resistance, metabolic syndrome, inflammation and risk for future coronary heart disease. In my opinion, these tests should most certainly be a part of any patient's assessment for metabolic disorders and development of heart disease:
1. Triglyceride to HDL ratio
This is a simple measure of insulin resistance, risk for diabetes mellitus type 2 and cardiovascular disease. A ratio less than 3.0 is considered normal, and more than or equal to 3.0 is suggestive of insulin resistance. An elevated ratio should prompt counseling the patient about therapeutic lifestyle change with close follow-up of metabolic markers for prevention of development of diabetes, hypertension and coronary artery disease.
2. Fasting insulin levels (and, if possible, two-hour postprandial insulin levels)
Usually at the yearly physical your physician will measure fasting blood sugar, and may even measure hemoglobin A1c levels, which are markers for pre-diabetes and diabetes. In my opinion, abnormalities in these are late developments. Insulin is a hormone produced by cells in the pancreas; it's responsible for regulating blood sugar levels and for promoting uptake of glucose into the cells for use as energy or for storage as fat. Measuring insulin levels two hours after a glucose load may be the first indication of metabolic problems in your handling of sugar (or carbs).
Sometimes a two-hour insulin measurement may be difficult, so in my practice I measure fasting insulin levels, which are the second measure to go up. These two can be early markers of insulin resistance, much before fasting blood sugar starts going up. Excessive insulin levels lead to increased serum triglyceride levels, decreased serum HDL (good cholesterol) levels, increase in levels of the small dense LDL (the plaque-promoting form of bad cholesterol) particles. Insulin resistance is a risk factor for hyperlipidemia, diabetes, hypertension, all of which contribute to atherosclerosis and plaque formation, which in turn is a risk factor for heart disease development. I encourage my patients to work toward a fasting insulin level of at least less than 6 microunits per mL (ideal is 4).
3. High-sensitivity C-reactive protein (hsCRP)
CRP is produced in the liver in response to nonspecific inflammation in the body. The high-sensitivity CRP is an assay which detects low levels of CRP specific to inflammation in the blood stream i.e., vascular inflammation, which could be the cause for development and progression of heart disease. Standard lipid tests do not test for inflammation, and this marker can be easily tested through your local labs. Even if your lipid profile is normal and you do not have other cardiovascular disease risk factors like hypertension or obesity or diabetes, if this marker is elevated, it is cause for concern. If somebody has already had a cardiac event like a heart attack or stroke, and this marker stays chronically elevated, it could be predictive of a high risk for future repeat heart attack or stroke. The therapeutic goal for hs-CRP is less than 0.7 mg/L, preferably as near to 0 as possible. I like to repeat this a few times to be sure it is actually staying high.
A word of caution with hs-CRP: though a marker of inflammation, it can also be a marker for infection and acute injury, so if you've had any recent surgery or procedure; have a respiratory, gum or other infection; or have the flu, please wait until your symptoms are resolved before testing, as this marker will be elevated due to that acute event.
4. Red blood cell magnesium levels
Red blood cell magnesium levels are the best way to assess magnesium status. Clinical signs of magnesium deficiency could be fatigue, weakness, muscle cramps, seizures, numbness and tingling in the extremities, mood and sleep issues, irregular heartbeats and also spasms in the arteries which feed the heart, contributing to heart attacks. Magnesium supplementation may reduce the risk of coronary heart disease, so try to keep levels at the high end of the lab range, though I monitor clinically more often.
5. Homocysteine levels
Homocysteine is a toxic amino acid and elevated levels can be a risk factor for development of cardiovascular disease and stroke. Elevated homocysteine levels damage LDL cholesterol, causing its oxidation. Oxidized LDL leads to plaque formation in the coronary arteries. Homocysteine is produced as an intermediate in the metabolism of amino acids methionine and cysteine. Activated forms of vitamin B12 and folate are needed for the conversion of homocysteine into methionine, so elevated homocysteine can be one of the indicators of deficiency in these important vitamins (remember that there are drugs like Methotrexate and acid blockers like Nexium which block the metabolism or absorption of these vitamins and may cause elevations in homocysteine levels). Serum homocysteine is great screening test for patients who are at a risk for cardiovascular disease and stroke, especially when there is a family history but no other known risk factors. Strive to keep levels around 8 micromoles/L.
6. Ferritin levels
Ferritin is an iron-containing protein produced in the liver, and signifies the stored form of iron. Ferritin can also be a marker of inflammation. Moderate elevation of ferritin may lead to a 2-3 times increased risk for development of diabetes. Though the normal range in your lab for ferritin can be from 12-150 ng/mL in women and 12-300 ng/mL in males, studies have shown high ferritin levels increase cardiovascular risk. Lowering the iron stores to near optimal level of between 70-80ng/mL will improve outcomes in cardiovascular disease including reduced risk for heart attacks, strokes and also improve life expectancy. As a side note, I don't think that ferritin levels less than 50ng/mL are in any way normal (even though your lab may show it in the normal range) and reasons for low iron stores must be looked into.
7. Testosterone levels (in males only — no correlation with heart disease has been found in women)
In males, testosterone deficiency has been associated with a high risk for cardiovascular disease. In elderly males, lower free testosterone level has been shown to be associated with a high prevalence of cardiovascular disease. If your total and free testosterone levels are low, work within integrative or a functional medicine physician to find out why that is the case. Replacing testosterone may not be the only answer.
Males should try to keep testosterone levels between 350-600ng/dl. Remember, more is not always better with testosterone therapy if you need it, and always seek out a physician well versed in male hormonal replacement therapies, or someone who can help guide you to support your body’s hormone production naturally!
8. Testing for chronic infections
Many pathogenic bugs have been shown to have a significant correlation with development of coronary heart disease as well as acute coronary syndromes (heart attacks). Some of these are herpes simplex virus, cytomegalovirus, and H. pylori. Ask your physician to test for antibodies to these bugs through your local laboratories.
Print out and take this list to your physician to help them better evaluate your risk for heart disease, or find a functional medicine physician who is well versed in managing and counseling patients with metabolic disorders!