If you want to prevent illness, it’s important to get the right screenings at the right time—but when is the right time. We cull through the recommendations, decade by decade.

In your 20s: Physical exams

In your 20s, you might feel young and invincible, but regular checkups should be on your to-do list anyway. These visits help your doctor construct a baseline picture of your general health.

“Everybody needs regular assessments for high blood pressure, diabetes, cardiovascular risk, tobacco use, alcohol, drugs, diet, exercise level, vaccinations, presence of depression, HIV, and other risk factors,” says William A. Curry, MD, professor of general internal medicine at the University of Alabama School of Medicine in Birmingham. Most of these assessments can be tackled during a physical with your primary care physician. If you don’t yet have a primary care physician, here are 7 secrets to finding a doctor you can trust.

In your 20s: Gynecologic Exams

Women in their 20s should begin pelvic exams, clinical breast exams, and screenings for cervical cancer. Experts also recommend Pap smears, but how often you need one will depend on your personal health history.

“From 21 to 29, a Pap smear is recommended every three years if tests are normal,” says Salena Zanotti, MD, an OB/GYN specialist with the Cleveland Clinic. “From ages 30 to 65, they’re only needed every five years with a human papillomavirus (HPV) co-test if you have no history of abnormal Pap smears.” These are 8 signs of cervical cancer you should never ignore.

In your 20s: STD screenings

In your 20s or earlier—as soon as you become sexually active—you should start getting regular checkups for sexually transmitted diseases (STDs), according to the U.S. Preventive Services Task Force (USPSTF), a volunteer panel of doctors and nationally-recognized experts that issues guidelines for tests and screenings for Americans. If you change sexual partners before your next annual physical or if you change partners frequently, you should have an STD screening more often. A primary care physician can give you this test, as can gynecologists. STDs are at a record high: Here’s why you might be at risk.

A harsh truth about lung cancer is that it doesn’t usually cause symptoms until the cancer is already advanced and not able to be cured. That’s why the idea of screening – looking for lung cancer in people who do not have any symptoms – is appealing. It has the potential of finding the cancer earlier, when it’s easier to treat.

But screening carries risks that may outweigh the benefits for most people. The people who are most likely to benefit from screening are those at higher risk for lung cancer, such as people with a long history of smoking.

How lung screening works

A computed tomography (CT or CAT) scan uses x-rays to produce detailed cross-sectional images of the lungs. It’s better than a regular x-ray at finding lung tumors and showing them clearly. That’s why CT scans are used for lung cancer screening.

One drawback of a CT scan is that it finds a lot of abnormalities that turn out not to be cancer but that still need to be checked out to be sure. This may lead to additional scans or even more-invasive tests such as needle biopsies or even surgery to remove a portion of lung in some people. A small number of people who do not have cancer or have very early stage cancer have died from these tests. There is also a risk that comes with increased exposure to radiation, even though a low dose is used for lung screening.

To weigh the benefits and risks before issuing current guidelines, experts at the American Cancer Society reviewed several studies that looked at low-dose CT screening. The most significant was the National Lung Screening Trial (NLST). This study included more than 50,000 people aged 55 to 74 who were current or former smokers with at least a 30 pack-year history of smoking (equal to smoking a pack a day for 30 years, or 2 packs a day for 15 years) and who had not quit more than 15 years ago. The NLST found that people who got low-dose CT had a 20% lower chance of dying from lung cancer than those who got chest x-rays. However, some other trials have not found a benefit from screening.

The screening in the NLST was done at large teaching hospitals with access to a lot of medical specialists and comprehensive follow-up care. Most were National Cancer Institute cancer centers.

High-risk patients should consider getting screened

Because of the risks associated with low-dose CT scanning, and the possibility of doing more harm than good for people who are less likely to have lung cancer, the American Cancer Society recommends doctors discuss screening with people who are at high risk for developing the disease and help them make an informed decision about whether to get screened. If people do decide to get screened, they should get screened every year through age 74, as long as they are still healthy.

To be in the high-risk category, patients must be aged 55 to 74 years and have a smoking history equivalent to a pack a day for 30 years, and currently smoke or have quit within the past 15 years. To be a good candidate for screening, patients need to be in fairly good health. For example, they need to be able to have surgery and other treatments if lung cancer is found.

A bone density scan is an imaging test which quantifies bone density. The lower a patient’s bone density, the greater their risk for bone fractures.

Bone density scans can be prescribed for many reasons: to predict the chance of breaking a bone, therefore preventing such an occurrence, to diagnose osteoporosis, or to see how well bone density is improving or deteriorating over time.

What is osteoporosis?

Osteoporosis, literally meaning porous bone, is a condition in which bones are too weak and bristle. Normally, there is a good balance between bone regeneration and bone destruction. If the body is losing too much bone, or not producing enough, osteoporosis can occur.

The risk factors for developing osteoporosis are: female gender, menopause, 60 years of age or older, a history of osteopenia or vitamin D deficiency, a sedentary lifestyle with poor physical exercise, low calcium diet, and certain medications such as corticosteroids.

Bone density scanning: 

Bone density scanning, also called densitometry, or DXA (Dual energy X-ray Absorptiometry) is a radiation-based imaging technique used to measure bone loss. It is the gold standard used to measure bone mineral density.

A DXA is a type of X-ray. As with all X-rays, a part of the body will be exposed to a small dose of radiation which will produce an image translating what’ going on in the body. Depending on the part of the body toward which the X-rays are directed, the DXA can either be central or peripheral.

A central DXA is what’s commonly prescribed; it investigates bone loss in the lower spine and hip bones.

A peripheral DXA may be prescribed in some cases, or if a central DXA is not available. it will measure bone density in areas like the forearms or wrists.

T score:

The bone density test results are reported using a special international score known as the T-score.

A T score basically compares your bone density to that of a healthy 30 year old adult. When your doctor receives your bone density results, they will look at your lowest T-score and conclude from there.

According to the WHO (World Health Organization), this is what a T-score means:

• A T-score of -1.0 or above is normal bone density.
• A T-score between -1.0 and -2.5 means you have low bone density or osteopenia.
• A T-score of -2.5 or below is a diagnosis of osteoporosis.
• The lower a person’s T-score, the lower the bone density.

Osteoporosis management:

If the densitometry results indeed show the presence of osteoporosis, some lifestyle changes are necessary to manage the condition and prevent any fractures.

Primary prevention is based on weight bearing endurance exercises to increase bone density. Certain fall prevention measures need to also be taken into consideration, such as getting proper eyewear if the person is visually challenged.

For secondary prevention, in people who have already sustained fractures, certain medications (known as Bisphosphonates) can be prescribed, in addition to the lifestyle changes.