Are You Getting the Most from Your Blood Tests? Even Doctors May Miss Signs of Health Problems

Unless your doctor tells you there's a problem, you may not give much thought to the blood tests that you receive periodically.

But standard blood tests and certain other blood tests that you may request from your doctor can offer valuable-even lifesaving clues about your health, including explanations for such vexing conditions as short-term memory loss and fatigue.

What you may not realize: If your doctor says that your test results are "normal," this is not the same as "optimal" or even "good."

For example, a total cholesterol reading of 200 mg/dL is considered normal, even though the risk of developing heart disease is sometimes higher at this level than it would be if your numbers were lower. Always ask your doctor what your target should be.

Blood test results that you should definitely make note of-and certain tests you may want to request... *

Low potassium. Low potassium (hypokalemia) is worrisome because it can cause fatigue, constipation and general weakness, along with heart palpitations.

Causes: An imbalance of the hormone insulin often causes low potassium. It also can be due to problems with the adrenal glands or a loss of fluids from vomiting and/or diarrhea. A magnesium deficiency or a high-sodium diet can lead to low potassium, too. It is also a common side effect of certain medications, including diuretics, such as hydrochlorothiazide... laxatives... and some asthma drugs, such as albuterol.

Normal potassium: 3.6 mEq/L to 5.2 mEq/L.

Optimal potassium: 4.5 mEq/L to 5.2 mEq/L.

What to do: If your potassium is not optimal, your doctor will probably recommend that you eat more potassium-rich foods, such as fruits (bananas, oranges, cantaloupe)... vegetables (tomatoes, sweet potatoes)... and whole grains (quinoa, buckwheat). You'll also be advised to reduce your sodium intake to less than 2,300 mg daily-high sodium depletes potassium from the body. Additionally, you may be advised to take a magnesium and potassium supplement.

Also: Keep your stress level low. Chronic stress can lead to a high level of the hormone cortisol-this can overwhelm the adrenal glands and lead to low potassium.

*These blood tests typically are covered by health insurance.

"Normal" glucose. Most people know that high fasting blood glucose (126 mg/dL or above) is a warning sign of diabetes. But you may not be aware that slight increases in blood sugar-even when it is still within the so-called normal range-also put you at greater risk.

Surprising: Among 46,000 people who were tracked for 10 years, for every one-point rise in fasting blood glucose over 84 mg/dL, the risk of developing diabetes increased by about 6%. Vascular and kidney damage may begin when glucose reaches 90 mg/dL-a level that's within the normal range.

Causes: High blood glucose usually occurs when the body's cells become resistant to the hormone insulin and/or when the pancreas doesn't produce enough insulin. Obesity and genetic factors are among the main causes.

Normal glucose: 65 mg/dL to 99 mg/dL

Optimal glucose: 70 mg/dL to 84 mg/dL.

What to do: If your fasting glucose isn't optimal or if tests show that it's rising, try to get the numbers down with regular exercise, weight loss and a healthier diet.

Powerful spice: Add one-quarter teaspoon of cinnamon to your food each day. People who take this small dose can lower their blood glucose by 18% to 29%.

Alternative: A standardized cinnamon extract in capsule form (125 mg to 250 mg, two to three times daily).

High homocysteine. Most doctors recommend a homocysteine test only for patients with existing heart problems. Everyone should get it. High homocysteine may damage arteries and increase the risk for heart disease and stroke.

Causes: Homocysteine rises if you don't get enough B-complex vitamins or if you're unable to properly metabolize methionine, an amino acid that's mainly found in meat, fish and dairy. Vegetarians tend to have higher homocysteine levels. Other causes include a lack of exercise, chronic stress, smoking and too much caffeine.

Normal homocysteine: Less than 15 umol/L.

Optimal homocysteine: 8 umol/L or below.

What to do: If your homocysteine level isn't optimal, take a daily B-complex vitamin supplement that has at least 50 mg of vitamin B-6.

Also helpful: A fish oil supplement to reduce inflammation and protect the arteries. Take 1,000 mg, two to three times daily.**

Low DHEA. This is a hormone that's used by the body to manufacture both testosterones and estrogen. It's also an antioxidant that supports the immune system and increases insulin sensitivity and the body's ability to metabolize fats. DHEA is not usually measured in standard blood tests, but all adults should request that their levels be tested.

Low DHEA is a common cause of fatigue, weight gain, depression and decreased libido in men and women of all ages. Over time, it can damage the hippocampus, the "memory center" of the brain.

Causes: It's normal for DHEA to slightly decrease with age. Larger deficiencies can indicate an autoimmune disease (such as rheumatoid arthritis) or chronic stress.

Normal DHEA: Levels of this hormone peak in one's late 20s. Normal levels vary widely with age and gender.

Optimal DHEA: The high end of the normal range is optimal-it reflects a reserve of DHEA.

Examples: 200 mcg/dL to 270 mcg/dL for men... and 120 mcg/dL to 180 mcg/dL for women.

What to do: If your DHEA level isn't optimal, managing emotional stress is critical. Get at least eight hours of sleep every night... exercise aerobically for about 30 minutes, three to four times a week. .. and practice relaxation techniques, such as yoga and meditation.

Also helpful: A daily supplement (25 mg to 50 mg) of DHEA. If you take this supplement, do so only under a doctor's supervision you'll need regular blood tests to ensure that your DHEA level doesn't get too high.

High LDL-P (LDL particle number). Traditional cholesterol tests look only at triglycerides and total LDL, and HDL cholesterol. I advise patients to get a fractionated cholesterol test for a more detailed picture.

Important: Patients with a large number of small LDL particles have an elevated risk for a heart attack even if their overall LDL level is normal. The greater the number of these cholesterol particles, the more likely they are to lodge in the lining of blood vessels and eventually trigger a heart attack.

Causes: Genetics is partly responsible for high LDL and LDL-P. A poor reading can be due to metabolic syndrome, a group of factors that includes abdominal obesity, elevated triglycerides and high blood pressure. A diet high in animal fats and processed foods also can cause an increase in LDL-P.

Normal LDL-P: Less than 1,300 nmol/L.

Optimal LDL-P: Below 1,000 nmol/L on an NMR lipoprofile (this test is the most accurate).

What to do: If your LDL-P level is not optimal (and you have not had a heart attack or other coronary event), I recommend exercise... weight loss... blood pressure and blood sugar management... more antioxidant-rich foods such as vegetables, berries and legumes... and three to five cups of green tea daily-it's a potent antioxidant that minimizes the oxidation of cholesterol molecules, which is important for reducing heart attacks.

Also: Daily supplements of bergamot extract, which has been shown to change the size of cholesterol particles (Earl Grey tea, which is flavored with oil of bergamot, provides a less potent dose)... and aged garlic extract, which has a beneficial effect on multiple cardiovascular risk factors. If these steps do not sufficiently improve your LDL-P level, talk to your doctor about taking a statin and/ or niacin.