Your doctor ordered a blood test. But do you understand the numbers? Or if you’re bordering on a heart attack, diabetes or underactive thyroid? We asked few experts to explain these critical medical test results – and what they say about your health.
1. Blood Pressure
Blood pressure is simply a measurement of the force of blood pushing against artery walls as your heart pumps blood through the body.
Your doctor will read off two numbers. The top, or systolic, is the pressure that occurs when your heart beats. The bottom, or diastolic, measures pressure when your ticker rests between beats.
If your blood pressure is higher than normal, you have hypertension, which “damages arteries, leading to strokes, kidney failure, blindness and heart attacks,” Wright says.
What’s optimal for your health: 120/80 mmHg. (That stands for millimeters of mercury, which is used to measure blood pressure.)
What’s not: A top number over 140 or a bottom number higher than 90 indicate high blood pressure.
A systolic number of 120-139 or a diastolic of 80-89 suggests pre-hypertension, which means you’re likely to end up with high blood pressure if you don’t exercise more or change your diet. Some people have low blood pressure, but this is a problem only if it causes fainting or dizziness.
The body needs some of this waxy, fatty substance to help it make hormones and vitamin D, for example. But too much cholesterol can accumulate on your arterial walls and lead to heart attacks and strokes.
Your body produces two kinds of cholesterol: HDL, or “high-density lipoprotein,” is good for you because it helps keep arteries clear. The higher this number, the lower your risk of heart disease.
Bad cholesterol, or LDL or “low-density lipoprotein,” can build up in arteries and form plaque, a hard substance that can slow or block blood flow. The bigger the LDL reading, the higher your cardiac disease risk.
Two other types of bad cholesterol, triglycerides and Lp(a) cholesterol, also contribute to arterial plaque buildup.
What’s optimal for your health:Total blood cholesterol should be below 200 mg/dL (which means milligrams per deciliter of blood).
- HDL should be over 50 for women
- LDL, less than 100 is optimal; 100-129 is near-optimal
What’s not: Total blood cholesterol of 200-239 is borderline high; over 240 is high.
- HDL: below 50 for women
- LDL: 130-159 is borderline high; 160-189 is high; 190 or above is very high
3. C-Reactive Protein (CRP)
Your liver produces this protein, and levels rise when arteries are inflamed or swollen. It’s a sign of cardiovascular disease.
A test called the hs-CRP (highly sensitive C-Reactive Protein) measures how much CRP is in your blood. People with high levels have twice the risk of heart attacks than those with low levels, according to the American Heart Association.
What’s optimal for your health: An hs-CRP level of less than 1.0 mg/L (milligrams per liter) indicates low risk; 1.0 to 3.0 mg/L means average risk.
What’s not: An hs-CRP level more than 3.0 mg/L indicates a high risk.
4. Thyroid Stimulating Hormone (TSH)
This simple blood test will tell you if your body is producing enough THS. The hormone is produced by the pituitary gland to help control hormones produced by the thyroid, a butterfly-shaped gland in the lower part of your neck just above the collarbone.
The thyroid controls many body processes, including bowel function, energy level and menstruation.
An underactive thyroid slows metabolism, creating hypothyroidism. Symptoms include unexplained weight gain, decreased appetite, feeling too cold, oversleeping, constipation, hair loss, reduced sex drive, infertility, depression and excessive fatigue.
An overactive thyroid speeds up your metabolism, a condition called hyperthyroidism. Symptoms include unexplained weight loss, increased appetite, feeling too hot, sleeping troubles, pounding heartbeat, diarrhea and feeling wound-up.
What’s optimal for your health: TSH from 0.4 to 4.0 mIU/L (milli-international units per liter)
What’s not: Over 4.0 mIU/L indicates hypothyroidism. Under 0.4 means hyperthyroidism.
5. Blood Sugar
A blood glucose test can indicate if your body is processing blood sugars properly and whether you’re at risk for diabetes, one of the leading causes of disability and death in the U.S.
When you eat, food is converted into blood sugar. In healthy people, a hormone called insulin, which is secreted by the pancreas, ushers glucose into cells throughout your body so it can fuel growth, cell repair and other functions.
In some people, insulin doesn’t do its job, either because the pancreas, a gland behind the stomach, doesn’t make enough or because the body is resistant to it. The result: Too much glucose stays in the blood and diabetes develops. Over time, excess blood sugar can damage blood vessels, heart, kidneys, eyes and nerves.
Three medical tests measure blood sugar levels: Hemoglobin A1C, fasting plasma glucose test (FPG) and oral glucose tolerance test (OGTT). Most doctors will do an FPG or OGTT, but the hemoglobin A1C is considered the most reliable.
“It shows how high blood sugars have been over the last three months,” says Laura C. Knobel, M.D., a family physician in Walpole, Mass., and a member of the Board of Directors of the American Academy of Family Physicians.
What’s optimal for your health: An A1C under 5.7%, an FPG under 100 mg/dL or OGTT below 140 mg/dL
What’s not:An A1 from 5.7% to 6.4% indicates pre-diabetes; over 6.4% is considered diabetes.
- FPG: 100-125 mg/dL indicates pre-diabetes; over 125 indicates diabetes
- OGTT: 140-200 mean pre-diabetes; over 200 is diabetes
6. Bone Mineral Density (BMD)
Doctors use bone mineral density tests to gauge skeletal health. The denser your bones, the stronger they are. But when they lose calcium (their primary substance) because of aging, poor diet, lack of exercise or a genetic predisposition, they become less dense, resulting in osteoporosis.
BMD test measures bone density against that of a healthy 30-year-old woman. The comparison is used to determine a T-score. A score of 0 means your bones are equal to that of a healthy 30-year-old. Higher numbers indicate stronger bones; lower indicates weaker ones.
With a BMD test, you may also get a Z-score, comparing your bone density to women your age. A Z-score is a less accurate way to diagnose osteoporosis, but it can tell your doctor if you’re starting to lose calcium.
What’s optimal for your health: A T-score of minus 1 to plus 1 and a Z-score above minus 2 is normal.
What’s not: T-scores from minus 1 to minus 2.5 indicate low bone density – a condition known as osteopenia.
- A T-score lower than minus 2.5 indicates osteoporosis. Z-scores below minus 2 require more testing.