Medical Tests & Procedures Archive

Your genes affect how your body responds to many drugs. But pharmacogenomic testing still isn't ready for routine use.

Most genetic tests focus on your odds of developing certain diseases or health conditions. But some — known as pharmacogenomic (or pharmacogenetic) tests — can reveal how your body may respond and react to different medications. To date, researchers have identified more than 400 genetic variations known to affect the metabolism of numerous drugs, including some that help lower cholesterol or prevent blood clots (see "Pharmacogenomics of common heart drugs").

In theory, knowing how people metabolize specific drugs could help doctors choose the safest, most effective treatment for their patients. But in practice, it's not that straightforward, says Dr. Jason Vassy, assistant professor of medicine at Harvard Medical School and a primary care physician at the VA Boston Healthcare System.

In the last decade, overall rates of colorectal cancer have been falling among the general population in the US. However, African Americans are more likely to develop colorectal cancer at younger ages, and to die from it. The reasons for this disparity are unclear, but they are rooted in socioeconomic and racial inequities.

Recent advances can help men with a worrisome PSA result avoid immediate biopsy.

Prostate-specific antigen (PSA) blood testing receives high marks as an effective way to monitor disease activity in men diagnosed with prostate cancer. Yet, as a screening tool for prostate cancer, PSA testing is problematic.

PSA naturally tends to increase as men get older, but levels that get too high may suggest prostate cancer. A PSA level of less than 4 nanograms per milliliter (ng/mL) is often reassuring, unless there has been a sudden jump from a much lower number. Many doctors consider a total PSA level higher than 10 ng/mL as the threshold for getting a biopsy to check for cancer.

Ask the doctor

Q. My aunt was having heart palpitations and recently found out that she has bigeminy. According to her doctor, it's not serious. But what exactly is this condition?

A. Bigeminy refers to a heartbeat marked by two beats close together with a pause following each pair of beats. The term comes from the Latin bigeminus, meaning double or paired (bi means two, geminus means twin).

There are wrong ways and right ways to measure your blood pressure. Watch Harvard Heart Letter Editor Patrick Skerrett demonstrate both.

Buy a monitor that meets the test

There are dozens of home blood pressure monitors on the market. You can buy a good one at your local pharmacy or a big-box store for anywhere between $60 and $100.

Ask the doctor

Q. In last month's Heart Letter, you described some of the ways your heart rate reflects your health. But I've also heard about another measurement, called heart rate variability. Can you explain what that's all about?

A. Heart rate variability (HRV) is a sophisticated measurement of the variation in time between each heartbeat. We know that a heart rate that's too slow, too fast, or irregular can signal a problem, so it's only natural to think that a steady, regular pulse is a sign of a healthy heart. And you might also assume that having little or no difference in the time between each beat (that is, a low HRV) is best.

News briefs

The pandemic may have you feeling reluctant to seek medical treatment. But when it comes to cancer care, even a short delay in treatment may lead to deadly outcomes, according to a review of 34 studies published online Nov. 4, 2020, by BMJ. Researchers evaluated treatment delay and survival in more than a million people who had cancer of the bladder, breast, colon, rectum, lung, cervix, or head and neck. Each four-week delay in treatment — whether surgery, radiation therapy, or medication (such as chemotherapy or immunotherapy) — was associated with an increase of 6% to 8% in the likelihood of dying during the study period. Scientists say delays of up to eight weeks and 12 weeks further increased the risk of death. For example, in women who delayed breast cancer surgery by eight weeks, there was a 17% increased death risk; women who delayed surgery by 12 weeks had a 26% increase. Keep in mind, there are lots of unavoidable reasons why cancer treatment might be delayed, such as not being strong enough to undergo procedures or scheduling issues at a treatment center. But if there isn't a good reason to delay, it's best to get treatment as soon as possible.

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Ask the doctor

Q. Should I get a test for COVID-19 antibodies, even though I've never had any symptoms and I don't think I've had the virus?

A. A blood test for COVID-19 antibodies tells you if you have been infected in the past; it does not accurately tell you if you are currently infected. You can get an antibody test through your doctor, or possibly through a testing center set up by your state or city.

Ask the doctor

Q. Should I make my kids get tested for COVID-19 before they come to visit me?

A. As we go to press, in most communities in the United States and Europe, the virus still is widespread — particularly among young adults. Many young adults who become infected do not develop symptoms, and therefore may not suspect they are infected. Worse, they may be shedding the virus and able to infect others. Older people are more vulnerable to becoming severely ill from the virus than young adults (although some young adults and even children can become very ill). So if my kids had symptoms that might indicate they had COVID-19, I'd ask them not to come. If they had no symptoms but were living in a "hot spot," I'd ask them to get tested before they traveled — and not to visit if they tested positive. I would hate not to see the kids, but it's a sacrifice we have to make until we control the virus.

For people recently diagnosed, taming the heart's rhythm rather than slowing it down may be a better approach.

The heart rhythm disorder known as atrial fibrillation (afib) occurs when the heart's electrical system goes awry. Instead of the heart's natural pacemaker creating a steady beat, the heart's upper chambers (atria) pulsate rapidly — up to hundreds of times per minute. Most of the electrical impulses telling the lower chambers (ventricles) to contract don't get through but many do, triggering a racing, irregular heartbeat that can leave people dizzy, breathless, or fatigued.

Therapies to tackle this common arrhythmia have improved over the years. Now, new findings suggest it may be time to rethink the treatment for people newly diagnosed with afib (see "Afib: Rhythm vs. rate control").