What's really up, doc?

Parkinson's disease

· Commonly misdiagnosed as: depression, rheumatoid arthritis and other conditions

It is estimated that five to 10% of people with Parkinson's disease, a degenerative disease of the nervous system associated with trembling of the arms and legs, stiffness and rigidity of the muscles and slowness of movement, are misdiagnosed. Parkinson's affects 8,000-10,000 new people in the UK each year: on average one person in every 500 has it.

Onset of symptoms is slow and may go unnoticed for several years but early signs include stiffness of fingers or a stiff shoulder accompanied by stiffness of muscles. Tremor is often noticed first and usually provokes a visit to the doctor. However, up to 30% of sufferers may not have tremor, which can lead to further misdiagnosis. This week's report revealed that despite more than nine out of 10 GPs admitting to having no specialist knowledge of Parkinson's, nearly one in five is failing to refer people suspected with Parkinson's immediately to a specialist and instead initiate treatment themselves.

"An accurate diagnosis and treatment from a specialist is the first step to someone with Parkinson's being able to continue living life to the full," says Robert Meadowcroft, director of policy, campaigns and information at the Parkinson's Disease Society. "The PDS is deeply concerned that some people with Parkinson's are never referred to a specialist."

Frequent fainting

· Commonly misdiagnosed as: epilepsy

A study published a few years ago revealed that many as 40% of Britons prescribed strong drugs for epilepsy actually have heart problems which could easily be treated. According to researchers at Manchester Royal Infirmary, many people who faint frequently are not having epileptic fits; their bodies are twitching after they pass out due to a sudden drop in blood pressure. Epilepsy is caused by temporary electrical changes in the brain.

Dr Adam Fitzpatrick, consultant cardiologist at the Manchester Heart Centre who conducted the research, says: "These people are likely to be suffering from a cardiovascular condition which makes them faint because of a sudden drop in blood pressure. We don't know exactly how it is triggered but it is accompanied by a slowing heart rate." A major epileptic episode will involve stiffening of the limbs, followed by a rhythmic jerking and, to the untrained eye, "It can appear that the people who are fainting are having an epileptic fit," he adds.

Bell's palsy

· Commonly misdiagnosed as: stroke

George Clooney and Pierce Brosnan have both suffered from Bell's palsy, a form of facial paralysis that is temporary and usually affects one side of the face. It can last anything from a few weeks to many years. About 25 people in every 100,000 develop Bell's palsy each year and most initially think they have suffered a stroke.

According to the Bell's Palsy Association, symptoms usually include a drooping eye, sagging mouth, facial pain and drooling, which may lead to it being mistaken for a stroke. There are numerous potential causes, though it is currently thought that most cases arise from herpes simplex virus infections (the one that gives you cold sores). Steroid therapy is the usual treatment although there is little evidence to suggest it is effective in the short term.

Ovarian cancer

· Commonly misdiagnosed as: irritable bowel syndrome

The UK has the highest incidence of ovarian cancer in Europe (around 7,000 women a year are diagnosed with it) yet many more cases slip through the net, according to Kate Law, clinical director for Cancer Research UK. "Symptoms of the disease include abdominal pain and bloating, diarrhoea, constipation, back pain and fatigue, all of which are also common with IBS," she says. "For that reason many women overlook the warning signs early on."

One British study found that 60% of GPs misdiagnosed cases of the disease, incorrectly assuming that symptoms occurred only in the late stages of ovarian cancer. If detected early, survival rates can be up to 90%. However, later diagnoses mean the survival rate drops to 30-40%. In the UK, 4,600 deaths occur from ovarian cancer every year, many of which could be prevented if awareness of the symptoms improved, Law says.

Pulmonary hypertension

· Commonly misdiagnosed as: asthma

Pulmonary hypertension is a relatively rare condition (there are an estimated 150,000 sufferers in Europe and the US) but one that has among the highest rates of misdiagnosis. It causes breathlessness and exhaustion, yet unlike asthma it occurs when high blood pressure builds up in the arteries that supply the lungs. This puts pressure on the heart and reduces the amount of oxygen that can reach the tissues.

In patients with pulmonary hypertension, the blood vessels in the lungs constrict, making the heart work harder. It can eventually lead to heart damage and even death. There is no cure, but there is effective medication if given early enough. For many, the cause of the condition is unknown. Despite its seriousness, one in five patients with PH has to wait more than two years to get correctly diagnosed. "The lack of awareness is very frustrating," says Iain Armstrong, chairman of the PHA-UK group and a pulmonary hypertension nurse at Sheffield Primary Care Trust.

Hepatitis C

· Commonly misdiagnosed as: fatigue, exhaustion or stress

This potentially fatal liver disease - the actor Pamela Anderson is a sufferer - can be caught through infected blood and is already the main reason for liver transplants. Experts say that by 2020 it will be killing more people than Aids.

Sometimes symptoms (including overwhelming fatigue) do not emerge for years after infection, one reason why many people with hepatitis C are misdiagnosed. Only 20% of sufferers realise they have the disease and less than 1% are receiving treatment, even though 60% could benefit from the drugs available. According to the Hepatitis C Trust, around 500,000 Britons probably have the disease; Italy, Spain and Germany are all better at diagnosing it. "We have a dreadfully poor track record at diagnosing the disease," says Charles Gore, chief executive of the trust. "More than 400,000 people are unaware they are affected."

If it is caught in time, hepatitis C can be treated with drugs that cure 40-80% of those infected.