What blood tests can (and can’t) tell you

Recall that Nollywood scene where a man in lab coat arrives with a blood test result and delivers the you-are-pregnant news to the hapless young girl? Turns out that’s not always so straightforward. There are a few things you can tell from a blood test, and a whole lot you can’t. Concussion.  This kind of […]

Recall that Nollywood scene where a man in lab coat arrives with a blood test result and delivers the you-are-pregnant news to the hapless young girl?

Turns out that’s not always so straightforward. There are a few things you can tell from a blood test, and a whole lot you can’t.

Concussion.  This kind of head injury can be hard to diagnose because there aren’t always obvious signs. Researchers have found that people who have concussions have special proteins in their blood, and they can hang around as long as a week after a blow to the head. This means your doctor may someday be able to use a blood test to help find out if you have one.

Something wrong. If your results for any blood test aren’t in the “normal” range, something is definitely wrong. False. They may be outside the normal range for lots of reasons, like your age, gender, or race. Other things — like what you’ve eaten, how much you drink, and medicines you take — can affect them, too. Your doctor will talk with you about your results and tell you what they might mean.

Depression. A blood test may be able to tell if you’re depressed. Scientists at Northwestern Medicine came up with this test that’s still in the research stage. It may also be able to tell if your therapy or medication is working.

Prostate cancer. A prostate-specific antigen (PSA) test measures how much of a certain protein is in your blood. Too much could be a sign of cancer, but it could mean other things, too, like a urinary tract infection. You’ll need further testing to find out if it’s cancer. 

Complete blood Count. This workup tells your doctor a lot about your health. White blood cells help fight infection, red blood cells carry oxygen, and platelets help your blood clot. Your doctor might suggest you have this kind of test if you have certain symptoms or a condition that can affect your blood cells.

How many colds in history? When you’re sick, your body makes special white blood cells to attack bacteria, viruses, and other things that shouldn’t be in your body. These special cells are called antibodies, and they stay in your blood for years or even decades. Researchers are working on a blood test that could tell your doctor what kinds of infections you’ve had.

 Blood tests are always right? They’re usually accurate, but mistakes can happen. A test that shows something is wrong when everything is fine is called a false positive. A false negative is when a test doesn’t find something that’s wrong with you. In some cases, if a result is outside the normal range for you, your doctor might recommend another blood test.

Basic metabolic panel (BMP). This common test tells your doctor a lot about how your body is working, including how your kidneys are doing, whether you’re dehydrated, and the levels of sugar, calcium, sodium, potassium, and other important things in your blood.

Heart disease. Worried about this? Get a blood test. Among other things, your doctor will want to know your cholesterol levels. If yours are outside the normal range, you might have a higher chance of coronary heart disease. You may need to fast (not eat or drink anything but water) for 9 to 12 hours before this kind of test. Your doctor will let you know if you do.

Want to know you’re pregnant—urine or blood test? Pregnancy tests look for a special hormone in your blood or urine that’s only there if you’re pregnant. Blood tests can pick it up before you’d even notice your period is late. At-home urine tests are most accurate after you’ve missed your period.