Radiation from these tests can increase your cancer risk.

If you’ve suffered a serious injury or your doctor suspects cancer, a CT scan could be lifesaving. But since 1980, the number of those tests done each year has grown from fewer than 3 million to more than 80 million. And recent re­search suggests that roughly a third of them serve little if any medical purpose. Even when appropriate, doctors and technicians don’t always take the steps needed to limit exposure.

Researchers estimate, in fact, that at least 2 percent of all future cancers in the U.S.—about 29,000 cases and 15,000 deaths each year—are likely to come from CT scans alone. Although the threat is greatest in children, older people face risks, too, and some research suggests that our susceptibility to certain radiation-induced cancer does not diminish as much with age as once thought.

Read more: When to question CT scans and X-rays

Rheumatoid arthritis (RA) is an immune system disease whichattacks the tissues in the body. Early symptoms of RA affect joints in the hand, wrist, knees,ankles, and feet and include pain, swelling, and stiffness of the joints. Severe symptoms include loss of joint movement and even joint deformity. It is possible for the disease to go into remission causing the pain and swelling in early stages to disappear. However, those symptomswill appear again later.

When diagnosing this disease there are several tests that come into play. One of those is a blood test that confirms whether a person is seropositive or seronegative. Being seropositive does not mean that you absolutely have RA; it does help determine conclusively that a person has the disease when other tests show a similar outcome.

Read more: How is Seropositive Rheumatoid Arthritis Diagnosed?

Rheumatoid arthritis can be difficult to diagnose. Many other conditions resemble RA. Its symptoms can develop insidiously. Blood tests and x-rays may show normal results for months after the onset of joint pain.

Read more: 7 Facts About a Rheumatoid Arthritis Diagnosis

Lupus and other rheumatic diseases can cause neurological symptoms such as headaches and seizures, which can delay a correct diagnosis for months, a new report says.

Treatments for rheumatic diseases can also cause these types of symptoms, according to neurologists at Loyola University Medical Center in Maywood, Ill. Rheumatic disorders include autoimmune and inflammatory diseases of the joints and soft tissues, such as lupus, systemic vasculitis and ankylosing spondylitis.

Read more: Certain Symptoms Can Delay Lupus Diagnosis