If you’ve seen your primary-care physician in the past several years, you have probably received at least one referral to a specialist — a doctor with advanced education and training in a specific area of medicine. (According to a 2012 Archives of Internal Medicine report, the likelihood that a doctor’s visit led to a referral to another doctor increased by 94 percent between 1999 and 2009.)

Usually, the reason your PCP suggests that you see a specialist is a good one: You have a problem that would benefit from such expert care. But in some cases, there may be other reasons — because your PCP is so time-pressured, for example. You don’t want to have more health-care providers on your team than necessary: The more doctors you see, the more tests and procedures you’re likely to undergo, and the higher your out-of-pocket costs.

So how do you know when you really need to see a specialist? Orly Avitzur, Consumer Reports’ medical director, describes four instances:

You’re not seeing a solution. If you’re experiencing health problems and feel that your PCP just isn’t getting to the bottom of them, it may be time for a specialist — especially if you have a constellation of symptoms that don’t seem to make sense to your doctor. The same holds true if you don’t feel better after trying a treatment that your PCP had expected to work well or if you’ve read about treatments with which your PCP is not familiar.

After a life-changing diagnosis. Some conditions create the need for significant life changes.

For example, if you’re told you have rheumatoid arthritis, your doctor may recommend powerful biologic medications, such as etanercept (Enbrel), which have the potential for serious side effects including severe immune reactions. Or if you’re diagnosed with diabetes, you may need drugs such as insulin, which call for close monitoring by a doctor. Parkinson’s disease or a stroke may require you to make physical changes to your home to accommodate your physical needs over time or significant adjustments to activities such as work and driving.

Before you make permanent changes in your life, ask your doctor to refer you to a specialist, who can be sure you’ve gotten the right diagnosis and tell you whether other treatment options are available.

For a complex chronic condition. While many PCPs are skilled at managing lifelong conditions including diabetes, people with some chronic diseases — notably those who need frequent adjustments in treatment or have flare-ups or health crises that require a doctor’s very close attention — are best served by specialists who have been expressly trained to treat them. They include disorders such as cardiomyopathy (a heart muscle disease), pulmonary hypertension (high blood pressure that affects both heart and lung arteries) and frequent seizures. Specialists are required to stay up-to-date in their particular fields with activities such as continuing medical education.

You’re dealing with a rare disease. If you have a rare disease such as cystic fibrosis, Huntington’s disease or muscular dystrophy, it’s important to work with a specialist or even a subspecialist (someone whose practice is focused on only one or a few conditions) who will have access to more resources for diagnosis and treatment and who is likely to be more knowledgeable about possible new therapies in the pipeline. There are many rare diseases — more than 6,800 at last count — that altogether affect an estimated 25 million to 30 million people in the United States. And PCPs encounter them so infrequently that they may not be able to diagnose them.

If you think you would benefit from seeing a specialist, ask your PCP to recommend one who participates in your health plan. Or if you know what kind of specialist you might need to see, you can check your insurer’s list of providers or contact the specialty’s professional society for a list of providers in your area. You’ll find links to all of those organizations at the American Board of Medical Specialties website, at abms.org.

Copyright 2016. Consumers Union of United States Inc.

For further guidance, go to ConsumerReports.org/Health, where more detailed information, including CR’s ratings of prescription drugs, treatments, hospitals and healthy-living products, is available to subscribers.