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Diagnosis

Osteoarthritis

Visit your GP if you believe that you have osteoarthritis (OA). Although there is no definitive test for osteoarthritis, he/she will ask about your symptoms. Make sure you give a good description of pain, any stiffness and joint function. Your GP may examine your joints including checking for bony swellings, joint tenderness, instability, excess fluid, creaking joint (crepitus) and restricted movement. They may check your muscles too, especially for muscle thinning.

The factors which may lead the GP to suspect OA include:

  • being over 50 years of age
  • persistent joint pain which gets worse if you use your joints more
  • having stiffness in the joints in the morning lasting less than half an hour

If your symptoms are slightly different from those listed above, your GP may think you have another form of arthritis. For example, if you have joint stiffness in the morning that lasts longer than an hour, you may have a more inflammatory form of arthritis.

Hip x-ray

Further tests

Further tests such as X-rays can confirm osteoarthritis, although an X-ray may not be needed. An X-ray can show bony spurs, the narrowing of spaces between bones or whether calcium has settled into a joint. X-rays cannot indicate the degree of pain you might feel.

Blood tests may be used only to exclude other possibilities. However, they are not always required 

If you have been diagnosed with osteoarthrits then you might find out Living with Ostearthritis factsheet of use.

Rheumatoid arthritis

Rheumatoid arthritis (RA) can be difficult to diagnose and there is no single test.

A GP will ask about symptoms, check joints for swelling and assess how easily they move, examine your skin and test muscle strength. If it is thought that you have rheumatoid arthritis you will be referred to a rheumatologist for an X-ray

Some of the tests which may be carried out either by a rheumatologist or the GP are outlined below:

Blood tests

No blood test definitively diagnoses rheumatoid arthritis:

Erythrocyte sedimentation rate (ESR)

In an ESR test, a sample of blood is put into a tube. The red blood cells (erythrocytes) are then timed to see how fast they fall to the bottom of the tube (measured in millimetres per hour). If the rate is faster than usual, you may have an inflammatory condition, such as rheumatoid arthritis, because proteins present in inflammation make them fall faster.

C-reactive protein (CRP)

A CRP is a non-specific test which can indicate if there is inflammation anywhere in the body by checking how much CRP is present in your blood. CRP is produced by the liver and released into the bloodstream. Elevated levels show that there is inflammation.

Full blood count

The full blood count will assess the number of red blood cells, haemoglobin, white blood cells and platelets in the blood. A low number of red blood cells or specifically haemoglobin indicates anaemia. Anaemia is caused by an insufficiency of red blood cells/haemoglobin which carries oxygen. Five % of people with rheumatoid arthritis have anaemia. However anaemia can have many causes, including a lack of iron in your diet. Therefore having anaemia is not a definitive test for rheumatoid arthritis.

Rheumatoid factor

This blood test is designed to see if a specific antibody, known as the rheumatoid factor, is present in your blood. This antibody is present in 80 % of people with rheumatoid arthritis. However it cannot always be detected in the early stages of the condition. The antibody is also found in 5 % of people who do not have rheumatoid arthritis, so this test cannot confirm rheumatoid arthritis. If it is negative another antibody test (for anti-CCP) may be done which is more specific for the disease.

Joint imaging

X-rays of joints can help differentiate between different types of arthritis and a series of X-rays can give an indication of progression of rheumatoid arthritis. A chest X-ray may also be taken as both the disease and certain treatments (such as methotrexate) can affect your chest. Musculoskeletal ultrasound may be used to confirm the presence, distribution and severity of inflammation and joint damage. Magnetic resonance imaging (MRI)  scans can show what damage has been done to a joint.

Psoriatic arthritis

Your doctor will ask if there is a family history of arthritis. MRI scans, ultrasound scans and X-rays can be used to help confirm diagnosis. Blood tests may be used to exclude other conditions. For example a test for rheumatoid factor will help rule out rheumatoid arthritis.

 Juvenile idiopathic arthritis

The GP will ask questions and examine you to exclude other conditions which could cause joint pain. No test confirms juvenile idiopathic arthritis (JIA).

What tests are there for JIA?

  • Blood tests are often used to make a diagnosis by showing evidence of inflammation and antibodies. (see Rheumatoid Arthritis for more details).
  • X-rays of the affected joints allow any joint damage to be seen.
  • Ultrasound and magnetic resonance imaging (MRI) scans delineate bony changes, joint damage and extent of synovitis.
  • Aspiration of a joint is where the fluid from a swollen joint is removed to be tested to differentiate it from septic arthritis.
  • Other tests such as a chest X-ray or a heart scan (called an echocardiogram) look for inflammation of the covering of the heart (pericarditis). This can occur in the systemic-onset type of JIA.

Fibromyalgia

Fibromyalgia is often difficult to diagnose because of the diversity of symptoms and these symptoms could have other causes. For example, an underactive thyroid gland (hypothyroidism) can produce similar symptoms. There are no specific blood tests, X-rays or scans that can confirm a diagnosis of fibromyalgia. All the tests, X-rays and scans will give normal results and are used to exclude other causes hence suggesting that you have fibromyalgia.

In the past diagnosis was founded on there being certain tender areas of the body which are painful when touched. In order for fibromyalgia to be diagnosed, certain criteria usually have to be met. Now the commonly used criteria are:

  • you have experienced severe pain in three to six different areas of your body, or you have experienced milder pain in seven or more different areas of the sbody
  • for the previous three months your symptoms have remained at broadly the same level
  • no other reason for the pain can be identified

 Polymyalgia rheumatica

Your GP should be able to start the diagnosis process for polymyalgia rheumatica (PMR) if you are 60 and over and you experience the following symptoms:

  • shoulder pain and stiffness in both shoulders, morning stiffness that lasts at least 45 minutes to an hour
  • high levels of inflammation measured by blood tests
  • new pain around both hips
  • small joints such as those in the feet are unaffected
  • no evidence to indicate rheumatoid arthritis

If there are complicating factors, for example if the symptoms don't improve with steroid treatment or if you have side effects from the treatment, you may be referred to a rheumatologist.

There are no blood tests for PMR but there are three which might be used to check for inflammation:

  • erythrocyte sedimentation rate (ESR)
  • plasma viscosity (PV)
  • C-reactive protein (CRP)

Finding the inflammation alone is not enough to confirm a diagnosis of PMR as it's also a feature of many other conditions, for example rheumatoid arthritis. You may therefore have tests – for example for rheumatoid factor or anti-CCP antibodies. These tests help exclude other conditions and confirm the diagnosis of polymyalgia.

Imaging may be used to help in the diagnosis of PMR and to exclude some other conditions. Ultrasound of the shoulders and hips may be used and can often show inflammation in the tissues. Magnetic resonance imaging (MRI) and positron emission tomography (PET) may also be used by the medical practitioner.

Anaemia (a lack of red blood cells) is quite common in PMR so your doctor may test for this, although it is not unique to PMR.

If your doctor suspects you have giant cell arteritis (GCA) which is a condition which causes inflammation to blood vessels, he may take a biopsy. This is a sample of tissue taken from an artery in your scalp and examined under a microscope.

Blood tests

Reactive arthritis

Reactive arthritis can usually be distinguished from other types of arthritis because of a link to an earlier infection. Your doctor will therefore probably ask about your recent health and sexual activity if reactive arthritis is suspected.

Diagnosis is usually made on one of the following symptoms or signs:

  • you suddenly develop symptoms just after an infection
  • the test results from all other tests for different types of arthritis are negative
  • characteristic symptoms such as red, painful eyes or rash over the palms of the hand or soles of the feet

What tests are available?

Reactive arthritis is not diagnosed by a specific test, but the following procedures may help to diagnose reactive arthritis or exclude other causes of the symptoms:

  • blood tests to check for levels of inflammation and occasionally for the HLA-B27 gene
  • a stool sample, or swabs taken from your throat, penis or vagina, which can be tested for signs of inflammation or infection

The presence of antibodies (such as rheumatoid factor and anti-nuclear antibody) which indicate other forms of arthritis can be found by blood tests.

If your eyes are inflamed you may be referred to an ophthalmologist to exclude any serious cause, for example iritis.

Ankylosing spondylitis

The symptoms of ankylosing spondylitis (AS) are stiffness in the back, which is not affected by exercise, pain/swelling in other joints and fatigue. Ankylosing spondylitis should be diagnosed by a rheumatologist.

What tests are available?

There is no specific test for ankylosing spondylitis, so diagnosis involves piecing together different forms of evidence to come to a diagnosis:

  • how your symptoms have developed over time (including during the second half of the night)
  • a physical examination
  • blood tests – which may indicate inflammation in the active phase. Examples are C-reaction protein (CRP) test, erythrocyte sedimentation rate (ESR) or plasma viscosity (PV). All of these give similar information.

A blood test for the presence of the HLA-B27 gene can indicate but does not confirm that you have AS. This is because most people who have the disease test positive for it although some people who don’t have AS also have the gene.

X-rays may contribute evidence for diagnosis, though they are not helpful in the early development. Later, perhaps a number of years later, X-rays may show new bone deposits between the vertebrae. MRI scans may detect abnormalities earlier.

 

 Gout

A diagnosis of gout is usually based upon your medical history and an examination of your joints. You will also probably be asked about your diet and alcohol intake. Your doctor may suggest you have some tests.

What tests are there for gout?

  • A blood test, called a serum uric acid test can measure the amount of urate in your blood. A raised level strongly supports a diagnosis of gout but it is not definitive – not everyone with a raised level will develop crystals in the joint tissues. It is also possible for urate levels not to be raised when an acute attack happens.
  • An examination of synovial fluid can show any urate crystals present. Fluid is taken from your joint through a needle and examined under a microscope. It can sometimes be difficult to draw fluid from a smaller joint and samples are often taken from your knee, even if that is not the site of the gout. Crystals can also be identified from samples taken from tophi which are nodular masses of monosodium urate crystals in soft tissue.

X-rays may show poorly treated and established gout, but they’re rarely helpful in confirming the diagnosis. This is because the damage usually only develops after repeated attacks. They help to exclude other causes. 

Systemic lupus erythematosus

When a diagnosis of systemic lupus erythematosus (SLE or lupus) is made it will have taken into account your medical history, the results of blood tests and a physical examination. The blood tests may include:

  • an anti-nuclear antibody (ANA) test:  those with lupus test positive for anti-nuclear antibodies 95% of the time. Sometimes there are falsely positive results so the test cannot be used to confirm diagnosis

  • an anti-double-stranded DNA (anti-dsDNA) antibody test: anti-dsDNA antibodies are present in about 70% of people who have lupus so that there is a strong indication of lupus. Levels of antibody increase when the condition is more active

  • an anti-ro antibody test: apositive test result suggests that you might have Sjogren’s syndrome or skin rashes and the antibody can pass through the placenta
  • antiphospholipid antibody test: the possible results of having a positive test here means that a miscarriage is more likely
  • erthrocyte sedimentation rate (ESR) test: in an ESR test, a sample of blood is put into a tube. The red blood cells (erythrocytes) are then timed to see how fast they fall to the bottom of the tube (measured in millimetres per hour). If the rate is faster than usual, you may have an inflammatory condition, such as rheumatoid arthritis because proteins present in inflammation make them fall faster
  • kidney and liver function tests: tests for liver and kidney function include blood and urine tests. Protein in the urine or blood can show that your kidneys are not working properly. These could be followed by kidney filtration tests
  • blood cell counts: a number of types of blood cell are made in the bone marrow, so the prevalence of these cells in the blood indicates how well it is functioning or where it is affected by lupus or the drugs to treat it. The same tests can be used to monitor the condition once diagnosis has been made
  • complement level test: complement is a set of proteins which are part of the immune system and the numbers of these in the blood decrease as lupus becomes more active

These tests might include X-rays, ultrasound, magnetic resonance imaging (MRI) or computerised tomography. Scans of the heart, lungs, liver or spleen will also allow the doctor to check that they are working properly

A urine test can show if there’s protein or blood in the urine. This can help doctors to recognise a problem in your kidneys at a very early stage. You may need further tests, such as kidney filtration tests.

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