Lupus is a chronic autoimmune disease in which the immune system produces autoantibodies that attack healthy cells and tissues.
Chances are you may have started to hear more about lupus of late, after 23-year-old singer Selena Gomez announced she had been diagnosed with the condition in her late teens and underwent treatment for the disease last year.
Gomez is just one of the 1.5 million Americans that are estimated to have some form of lupus, and each year, more than 16,000 new cases are diagnosed in the US.
Around 90% of those diagnosed with lupus are women, with black women around three times more likely to develop the condition than white women.
But what exactly is lupus? What are its symptoms and complications? And why is it that we know so little about the disease? We investigate.
The causes, symptoms and complications of lupus
Lupus is a chronic autoimmune disease in which the immune system produces autoantibodies that attack healthy cells and tissues, including those of the skin, joints, heart, lung, kidneys and brain.
While the exact cause of lupus is unclear, the disease can be triggered by certain environmental factors, such as exposure to sunlight, stress and smoking. Pregnancy is also a common trigger for the condition among women.
Since lupus is most common among women during childbearing years, researchers speculate that the female hormone estrogen may play a role in disease development.
SLE is the most common form of lupus, which can affect any part of the body.
In addition, it is suspected that lupus development may be influenced by certain genes, though researchers believe it is unlikely that genes alone trigger the disease, but that it is rather a combination of factors.
There are many different forms of lupus. Systemic lupus erythematosus (SLE) is the most common, accounting for around 70% of all cases. In SLE, any part of the body can be affected, though around 80% of cases involve the skin.
Symptoms of SLE include chest pain, shortness of breath, muscle pain, fatigue, fever, hair loss, mouth sores, light sensitivity, anemia and skin rash - most commonly a butterfly-shaped rash that spans the cheeks and bridge of the nose.
Other forms of lupus include cutaneous lupus erythematosus, which is limited to the skin, and drug-induced lupus erythematosus, which can be triggered by certain prescription drugs, including hydralazine and procainamide. Symptoms of drug-induced lupus are similar to those of SLE, though the major organs are rarely affected.
The majority of people with lupus often experience "flare-ups," in which symptoms worsen for a period of time before improving or disappearing completely.
Complications from lupus depend on what part of the body is affected. Individuals with inflammation in the brain, for example, may experience headaches, memory problems and confusion and are at greater risk for stroke.
Lupus can cause severe kidney damage; around 40% of people with lupus experience kidney complications and it is one of the leading causes of death among people with the condition.
Inflammation of the blood vessels - known as vasculitis - or inflammation of the heart also raises the risk for heart attack and cardiovascular disease for people who have lupus; people with lupus are twice as likely to develop cardiovascular disease than those without the condition.
Individuals with lupus are also more susceptible to infection because the disease and its treatments can weaken the immune system. Respiratory tract infections, urinary tract infections, salmonella, herpes, shingles and yeast infections are among the most common.
Lupus: 'the great imitator'
Lupus is often deemed the "great imitator" because the symptoms of the disease are so similar to other conditions, meaning the disease is often mistaken for other illnesses by both patients and doctors.
According to the 2014 "UNVEIL" survey, conducted by Lupus Foundation of America and Eli Lilly, it takes an average of 6 years for someone with lupus to receive a diagnosis from when symptoms first present themselves.
In addition, the survey revealed that 66% of people with lupus reported being incorrectly diagnosed, while more than half of these participants reported seeing at least four health care providers before being accurately diagnosed.
What is more, each patient with lupus will present very different symptoms, making the condition even trickier to diagnose.
Dr. Susan Manzi, co-director of the Lupus Center of Excellence in Pittsburgh, PA, explains:
"One of the greatest mysteries of lupus is that it affects different people in different ways - no two cases are exactly alike. This disparity makes lupus one of the most difficult diseases for physicians to diagnose, treat, and manage."
What makes diagnosis harder is that there is no single test to identify the disease. Lupus is commonly identified through a combination of blood and urine tests, physical examination and biopsies.
Blood tests may be conducted to determine whether a patient has a low white blood cell or platelet count, or whether they have low hemoglobin levels - a protein found in red blood cells - all of which can be indicators of lupus.
The antinuclear antibody (ANA) test is another way in which doctors may diagnose lupus. The majority of people with lupus test positive for ANA, though a positive result is not a definitive indicator of the condition; positive ANA tests can occur in around 5-10% of healthy women.
Urine tests may be carried out in order to identify an increase in protein levels or red blood cells, which can be a sign that lupus is affecting the kidneys
A doctor may also perform a skin or kidney biopsy in order to diagnose lupus. The samples are viewed under a microscope and assessed for changes that may indicate the presence of the disease.
How lupus is treated
There is no cure for lupus, but there are a number of treatments that may help manage the condition. Such treatments aim to prevent flare-ups, alleviate symptoms and reduce organ damage and other complications.
The treatment an individual with lupus receives is dependent on their symptoms, though medications are likely to play an important role in managing the disease.
NSAIDs such as aspirin are a common treatment for lupus.
Some common medications for mild cases of lupus include non-steroidal anti-inflammatory drugs (NSAIDs) and corticosteroids, which can reduce pain and swelling in the muscles and joints, and antimalarial drugs, which can help treat joint pain, skin rashes, fatigue and lung inflammation.
For more severe cases of lupus, a doctor may recommend the use of immunosuppressive medications or chemotherapy. These treatments work by curbing the immune system in order to prevent organ damage.
Treating lupus can be challenging, particularly given that the disease is so difficult to diagnose. However, it is important to note that existing treatments for the condition can be effective; around 80-90% of people treated for non-organ threatening lupus have the same lifespan as individuals free of lupus.
Still, there is no doubt that there is a need for more effective diagnostic and treatment strategies for lupus, and researchers are working hard to identify them.
Last year, for example, Medical News Today reported on a study by researchers from the University of Alabama at Birmingham that detailed the discovery of an immune protein called "Fc receptor" that influences development of the disease, as well as multiple sclerosis (MS).
According to the researchers, the Fc receptor regulates the production of antibodies produced by the immune system that attack foreign invaders in the body. The team found this receptor is mutated in people with lupus and MS, leading to an overproduction of antibodies and an attack on healthy tissues.
"This new finding could play a significant role in the way companies design treatments for autoimmune diseases, in a more targeted approach," commented study coauthor Dr. Robert Kimberly. "Now efforts can be made to target the individuals who will benefit from the treatments, based on the gene mutation."
The challenges of living with lupus
Lupus is a difficult disease to live with. Though current treatments can help alleviate certain symptoms, there will still be days when the condition can take such a toll, it can be hard to simply get out of bed.
"One day, I washed my face and brushed the washcloth across my eyelashes," 36-year-old Sharon Harris, president and founder of Lupus Detroit - who was diagnosed with lupus aged 23 - recently told ABC News. "[It] stopped me dead in my tracks. I was too exhausted to scream but it knocked the life out of me so much so that I had to sit on the edge of the tub to regroup. My eyelashes hurt - I will never forget that."
But it is not just the physical symptoms that can make day-to-day life difficult for people with lupus; the disease can have a negative impact on mental health, too. The UNVEIL survey revealed that around 90% of people with lupus experience anxiety as a result of the condition and around 85% feel depressed.
Lupus can make a person feel tired and week, causing them to withdraw from social activities, which can make them feel isolated. Another challenge with lupus is that the disease is often "invisible," which can make it hard for others to understand what people with lupus are going through.
"You may face many who doubt the veracity of your illness, believing it is all in your head. This can be extremely painful, frustrating, causing anger and resentment," notes non-profit foundation Molly's Fund: Fighting Lupus.
Lupus can also change a person's lifestyle dramatically. They may need to give up work, for example, or they may need assistance with general everyday tasks, such as household chores, cooking or shopping.
'American public does not understand the serious nature of lupus'
While efforts are being made to find new ways to diagnose and treat lupus, there is one factor that continues to hamper progress: lack of awareness and knowledge about the disease.
As mentioned previously, more than 70% of people in the US aged 18-34 have never heard of lupus or do not know anything about it other than the name, which researchers and health care providers across the country believe is a concern.
"There is widespread confusion surrounding lupus, and the American public does not understand the serious nature of the disease," notes Sandra C. Raymond, president and CEO of the Lupus Foundation of America.
In response to this lack of awareness, the organization has set up a KNOW LUPUS campaign to increase public knowledge about the disease across the US, and each year, May is declared as National Lupus Awareness Month - a way to encourage fundraising and lupus awareness events across the country.
It is hoped that campaigns such as these will help educate people about what is a potentially devastating disease and ultimately lead to a much-needed cure.
As Wendy Rogers, a woman from California who is living with lupus, says:
"The more people know about lupus, the better support there will be for those living with the disease and the sooner we can conquer it."
Our Knowledge Center article "Lupus: causes, symptoms and treatments," offers further information about the disease.