Getting a Diagnosis
First, a clinical assessment
Who performs the assessment?
It is really important to understand at the outset that the assessment of a child or young person for possible arthritis needs to be done by a clinician with some experience of the condition. Arthritis affects 1 in a 1,000 children, so your General Practitioner (GP) may not have seen a child with arthritis before and may not be used to assessing for it. They may therefore need to request an opinion from a paediatrician, paediatric rheumatologist or paediatric orthopaedic consultant.
What is assessed?
Making a diagnosis depends on asking you detailed questions about your child’s general health and illnesses, vaccinations, family history and carrying out a thorough physical examination. The diagnosis may also require your child to have some investigations, such as blood tests and scans.
Clinicians will take a very careful history of the problem, including questions such as:
Q) How long has it been going on?
Q) What seemed to trigger things off?
Q) What exactly is your child able to do or no longer do?
Q) Has any medication helped?
Q) Are there any additional symptoms with it such as fever, rash, altered poo?
They will ask about any past problems, birth, development, growth, weight loss and any family history of similar or associated illnesses.
Your child will be examined very carefully. Doctors often want to examine all parts of the child, not just the area that you are worried about. It often helps for your child to come with a pair of shorts and a vest to change into so that they can be examined easily without embarrassment. To get a more clear idea of what the doctor will be looking for, watch this video or visit 'What is JIA?').
Outcome of the clinical assessment visit
The doctor may be able to give you an explanation for your child’s difficulties after the above assessment and to share with you a way forward to help your child. Often no investigations are needed but if childhood arthritis is suspected, it is likely that a few basic investigations are performed.
A blood sample will often be taken and a number of tests are performed on these which include those listed below. In young children, blood is often taken from the back of the hand and a numbing cream or cold spray is put onto their hand before so that they will not feel anything when the needle goes in.
It’s important to note though, abnormal blood tests do not make a diagnosis of arthritis but simply add to the ‘picture’ the doctor is forming of the whole problem. By the same token your child can still have arthritis in the presence of normal blood tests.
Full Blood Count:
Haemoglobin (Hb) can be low if your child is anaemic. Anaemia commonly occurs through lack of iron in the diet. It can also occur in arthritis or in other long term conditions where there is ongoing inflammation (see ESR and CRP below).
White blood cell count (WBC). White blood cells help your body to fight infection and if there is infection your WBC is often raised. In some forms of childhood arthritis (eg. systemic onset JIA) the WBC count can also be raised.
Platelet count. Platelets help your blood to clot and the platelet count can go up when there is general inflammation. This can occur after infections and in arthritis (particularly systemic onset or polyarticular types of JIA).
Signs of inflammation (or Acute Phase Reactants). Inflammation simply means swelling, heat, redness, pain – and can occur anywhere in the body and be caused by a vast number of problems. Arthritis is simply inflammation occurring in a joint.
Erythrocyte Sedimentation Rate (ESR). If your blood is put into a glass test tube and left for some time, the red blood cells will all settle at the bottom, with the yellowish fluid (called ‘plasma’) on top. The ESR measures the time it takes for the red blood cells to settle. If there is inflammation in the body somewhere which has been there for at least a few days the time it takes for the red blood cells to settle to the bottom is prolonged. A raised ESR does not tell you where the inflammation is or what is causing it. There are many, many illnesses that can cause a rise in the ESR, including simple infections (colds, viruses and bacteria) and conditions such as arthritis. Once the ESR is raised it takes a few days or weeks to settle.
C-Reactive Protein (CRP) when raised in the blood is raised in response to infections and inflammation. It goes up particularly high in response to bacterial infections, but can also be raised with viral infections and with inflammation such as arthritis. It rises and returns to normal quicker than the ESR.
Ferritin is a protein which indicates the level of iron stores in the body. It is also an ‘acute phase reactant’ that will be raised in the presence of inflammation in the body. Ferritin rises particularly in children with systemic onset JIA. A complication of severe arthritis (Macrophage Activation Syndrome) will also result in very high ferritin levels.
Antibodies are proteins produced by white blood cells in response to infection (such as viruses or bacteria). They direct the immune system to fight against the infection. Auto-antibodies are the same type of proteins, but directed against our own bodies. The immune system can become triggered to fight our own body, and this can cause a variety of illness, including some forms of childhood arthritis. A number of complex factors come in to play and as always, it is not as simple as it sounds! The auto-antibodies may be found in fit, healthy, normal individuals and diseases may be present without any auto-antibodies.
Antinuclear antibody (ANA) is the commonest type of auto-antibody found in juvenile arthritis but, it is also found in up to 15% of normal children and in a number of other conditions. In a child with arthritis it seems to be associated with an increased chance of eye inflammation (uveitis).
Anti double stranded DNA (ds-DNA). This auto-antibody is commonly associated with a condition called Systemic Lupus Erythematosis (or SLE). SLE can cause a form of childhood arthritis.
Rheumatoid Factor (RF) and anti-cyclic citrullinated protein (anti-CCP), these auto-antibodies can be found in children and young people with arthritis but it is rare. They are most often found in teenage girls with a lot of joints affected by arthritis (polyarticular).
Anti-neutrophil cytoplasmic antibody (ANCA) is very rare in childhood but can be found in association with diseases that affect the blood vessels (named ‘vasculitis’).
Aspartate aminotransferase (AST) is an enzyme which is found in high concentrations in organs such as the liver, heart and kidneys and also in muscles. The blood test for AST in children with suspected or confirmed JIA is used to detect any damage to the liver which can occur because of the drugs used to treat JIA.
Alkaline phosphatase (ALP) is an enzyme found mainly in the liver but also in smaller amounts in the kidneys, heart, muscles and pancreas. If liver damage occurs increased amounts of ALP are released into the bloodstream. ALP and AST tests are often done together (see above) and also often before a child is started on methotrexate so the doctors have a baseline (start) measurement to compare with once treatment has started.
Parents may find it helpful to keep a monitoring booklet to record the results of all blood tests each time so you see how well your child is doing and also look at these against reference ranges. However, parents should be aware it is difficult to give absolute ‘normal’ ranges for blood test results because test ranges can vary between laboratories and also because of differences in childrens ages and gender. For more information about understanding these go to Lab Tests Online.
Slit lamp examination of the eyes
What is it? This is an examination of the eyes using a special light and magnification lens (‘slit lamp’) to look carefully at the front of the eye. An ophthalmologist (eye specialist based in hospital) will perform the test.
Who needs it? Any child with suspected arthritis should be referred to have their eyes examined. It is needed to screen for a condition called uveitis, or inflammation in the front part of the eye, which can go along with juvenile forms of arthritis. Unfortunately uveitis can be present without any symptoms of the condition, and it can lead to deterioration in vision and ultimately blindness if left untreated.
How often should my child have this test? Children with JIA should all have an initial slit-lamp eye examination within six weeks of diagnosis according to the British Society of Paediatric and Adolescent Rheumatology (BSPAR) and Royal College of Ophthalmologists (RCO). However, your child’s ophthalmologist[i] and/or rheumatologist will advise you about when and how often your child should be reviewed.
X-Rays (or radiographs) of affected joints
It is common for any joints where an abnormality is found during examination of your child (such as swelling, heat, redness, pain, tenderness, reduction in the normal range of movement) to have an X-Ray. This is to look for any hidden fractures, damage to the joint surfaces, very rare tumours, cysts etc. An X-ray can also detect some changes in the soft tissues (such as showing fluid in the joint, or soft tissue swelling) but these have to be fairly marked to show up on X-Ray. They can also be used by doctors performing joint injections to help identify the correct position in the joint to inject.
What is it? An X-ray is like a big camera which takes pictures of the inside of your body. X-rays are quick and painless.
What happens during an X-ray examination? When your child goes for an X-ray they may need to change into a hospital gown and take off any jewellery they may be wearing. This is because some clothing and jewellery make it difficult to see the images clearly. There will be cubicles where they can change.
The X-ray room is usually dimly lit and depending on which part of their body needs an X-ray your child may have to lie on a bed or stand against a board, but the radiographer will help them get into the correct position for the X-ray to be taken.
When the radiographer is ready to take the X-ray they will go behind a screen to operate the X-ray machine but they will be able to see and hear your child at all times. Before the X-ray is taken your child will be asked to keep very still so the image isn’t blurred.
Sometimes, the radiographer will have to take more than one X-ray from different angles to get as much information as possible. He/she will again help your child to get into the right position each time before taking the X-ray.
Parents can usually stay inside the room with their child whilst the X-ray is being taken unless you are pregnant. Before the X-ray is taken, you will be given a lead coat to wear. This will protect you from any radiation from the X-ray. Although the lead coat is heavy you will only need to wear it for a few minutes whilst the X-ray is being taken.
What happens next? The X-ray will be transferred to a computer so the doctor can look at this on a screen. Sometimes, they may also print out a copy. Once they have had a look at the X-ray they will send a report to the referring doctor who will discuss the results with you.
Are there any risks from X-ray? X-rays are made up of a type of radiation. However, the levels of radiation in an X-ray are very small and not much different to the natural exposure to radiation we experience every day so there’s no need for parents to worry. All hospitals also have protocols to make sure patients are only exposed to the minimum dose and only in the part of the body being X-rayed.
Ultrasound Scan (USS) of affected joints
What is it? An ultrasound scan is sometimes called a sonogram and is a harmless and painless procedure. It uses sound waves to create clear images of the soft tissues and the inside of joints and can show any swelling (synovitis), excessive fluid in the joint (effusion) or any damage to the smooth surfaces of the joint cartilage (erosion).
Most people will be familiar with ultrasound because they are used to look at a growing baby during pregnancy.
Who needs it? This is not an essential or even necessary examination in straightforward cases. However, it can help if there is any doubt about which joints are involved, whether any other tissues are affected (for example the tendons or ‘pulleys’) and whether there has been any damage (termed an ‘erosive arthritis’). A few paediatric rheumatologists will perform their own USS in clinic. Others will refer to specialist radiologists who will perform the scan and send the doctor a report.
Ultrasound scans are usually carried out in the X-ray Department in a hospital by a doctor or a sonographer.
What happens during an ultrasound scan? The room where the ultrasound scan is performed is usually dimly lit. This helps the sonographer see the images more easily on the monitor. Your child will need to lie on an examination table and the sonographer will put some clear gel on the part of their body to be scanned. This gel is harmless, although your child may find it a little cold, and it helps the small pen-like device (probe) held by the sonographer to move smoothly over the skin and ensures there is continuous contact between the probe and the skin.
The probe is connected to a computer and a monitor and pulses of sound waves sent from the probe through your child’s skin and into their body bounce back from structures inside your child’s body and are displayed as an image on the monitor. Ultrasound scans are quick and you can usually stay with your child throughout the procedure. When the scan is finished the sonographer will write a report for the doctor who referred your child so you can discuss the results with them. Sometimes, ultrasound scans are also used to help guide the doctor during some joint injections.
Are there any risks from ultrasound scans? Ultrasound is considered to be a very safe imaging procedure because it uses low power sound waves and does not expose the patient to any forms of radiation.
Computer Tomography (CT) Scan
What is it? CT scans are also sometimes referred to as a CAT scan. This stands for computer axial tomography. A CT scan is similar to an X-ray but instead of one image being taken the CT scanner takes lots of pictures to produce a 3-dimensional image. These images provide much more detail of the inside of the body and are really good for looking at blood vessels and soft tissue as well as bones. Like X-ray, CT uses radiation to produce these images.
What happens during a CT scan? A CT scanner looks like a large ring doughnut. Before the scan your child may need to change into a gown and remove any hair clips or earrings as these can interfere with the scan. Your child will have to lie on a bed either head first or feet first depending on which part of their body is being scanned. The radiographer will help your child to get in the right position on the table so the scan can be performed. During the scan the motorised bed moves into the centre of the scanner whilst the X-ray unit inside the scanner moves full circle around your child and takes the images.
CT scans are usually very quick but some scans may take a bit longer than others, it just depends on what part of the body is being imaged. It is very important that your child keeps very still whist they are being scanned so the images are not blurred. The radiographer will sit in another room whilst the CT scan is taking pictures but will be able to hear and see your child throughout and be able to talk to them through an intercom to reassure them.
Are there any risks from CT scans? CT scans use a slightly higher radiation dose than X-ray and so doctors limit their use in children. However, don’t worry if your child is referred for a CT scan because their doctor will have weighed up risks and decided this is the best type of examination for them.
Magnetic resonance imaging (MRI)
What is an MRI? Magnetic resonance imaging (MRI) is another type of imaging. It uses a magnet and radio signals to produce clear images of the inside of the body and is really good at showing bone, soft tissues, internal organs and blood vessels. Like CT images, MRI images are also 3-dimensional but unlike ultrasound it only produces static images and is not suitable for examination of moving joints.
Who needs it? It is not very common for children with suspected arthritis to need an MRI scan. If there is sufficient doubt about the cause of the child’s problems then a scan may be needed. Where joints are very deep and not so easy to examine (for example, the hips, the spine, or the joints of the pelvis – sacro-iliac joints) an MRI may be valuable. Where there is a history of a probable injury at the outset of the problem an MRI can detect this. If there is concern that a child with known arthritis is not better on treatment or may be developing damage an MRI may help determine the extent of the problem.
What happens during an MRI scan? The MRI scanner is like a wide tunnel, some longer than others. Before your child has an MRI you will be asked to fill in a questionnaire about your child. This is a safety precaution and will ask about any implants your child has because, although MRI is generally safe there are some implants, such as pacemakers, which cannot go into the scanning area.
Your child will need to lie on a bed in front of the MRI scanner. The radiographer will help your child get into the right position and sometimes, they may also put another piece of equipment around the part of the body the doctor wants to take a particular look at. This is called a coil and helps capture the image. Although your child’s doctor may have asked, for example, for an MRI of their knee, all of your child’s body will be inside of the scanner.
When your child is ready and feeling relaxed the radiographer will go into a separate room to operate the MRI scanner. The radiographer will still be able to speak to your child through the intercom and can also hear and see your child at all times. During the scan the MRI scanner makes a loud knocking sound. This is normal and your child will have been given headphones to wear to protect their hearing. It’s a good idea to take your child’s favourite music or story on CD so they can listen to this through the headphones whilst the scan is taking place. Usually, unless your child is having a general anaesthetic so the scan can be performed, you or another family member will be able to stay with them during the procedure as long as you can comply with the safety requirements. You should also be given headphones to wear throughout the scan for protection.
MRI scans do not hurt and last for a minimum of 15 minutes. It is very important your child lies very still throughout the scan. However, if you and/or the doctor think it will be difficult for your child to stay still, the MRI may be done under general anaesthetic but this depends on your child’s age and which part of the body is being scanned. After the scan has finished the radiologist will look at the images and write a report for your child’s doctor who will discuss the results with you at your child’s follow-up appointment.
Are there any risks from MRI scans? Patients referred for an MRI or anyone accompanying them during the scan who have certain implants or metal fragments are not allowed into the MRI room. However, the radiographer will look at the safety questionnaire(s) you filled in prior to the scan and talk to you about any safety issues before deciding whether it is safe to be exposed to the scanning equipment.
Sometimes CT and MRI scans give the doctor more information when they are done with a liquid called contrast agent. This is a special liquid which makes certain structures and areas in the body appear much clearer on the image and help to show up areas of inflammation, for example. Contrast agents used during CT (iodine based agent) and MRI (gadolinium agent) scans are injected into the vein, usually in the arm, via a cannula (a soft, hollow plastic tube). The cannula is inserted through the skin into the vein using a needle and once the cannula is in place the needle is removed leaving a small thin plastic tube in the blood vessel. This should be comfortable and will only be in place until the scan is finished. Sometimes, if you child requires an examination of their bowel (intestines) they may have to have a drink which contains a contrast agent.
Before your child is given any contrast agent you will be asked some safety questions to reduce the risk of your child having any reaction to them. Sometimes patients have experienced mild reactions such as nausea and vomiting, flushing, mild skin rash or hives with iodine based agents. Patients are very rarely affected by gadolinium based agents but may experience hives or itchy eyes and sometimes it may feel very cold as it is being injected. However, all these reactions are short-lived. Once the scan is over these contrast agents are filtered through your child’s kidneys and excreted in their urine.
Examination of the joint fluid
When infection is suspected
If there is any chance (from the history or examination) that your child has an acute bacterial infection in a joint they will need to be admitted to hospital and have a sample of fluid taken from the joint which is then sent to the laboratory to test for infection. Usually an orthopaedic specialist does this under a general anaesthetic in theatre and the joint is ‘washed out’ at the same time. An infection may be indicated by sudden onset (one or two days only) of pain, swelling, heat and an inability to move the joint and is often accompanied by high fevers, going off food and feeling generally unwell.
When arthritis is suspected
If arthritis is strongly suspected and there are only a few joints affected, a steroid injection is commonly recommended. Sometimes when this is done for the first time the clinician will send a sample of fluid to the laboratory. This is to look for very rare conditions such as gout or tuberculosis and to check that the fluid looks as expected under the microscope.
A description of all these investigations can be found in greater detail on the NHS Choices website, http://www.nhs.uk/Pages/HomePage.aspx
for example MRI scan details can be found at: http://www.nhs.uk/Conditions/MRI-scan/Pages/Introduction.aspx.
See also the article: “What’s the difference: An explanation of the different imaging procedures” on the JIA-at-NRAS website (add Link).
For further information about the different types of blood results and what they mean go to: http://labtestsonline.org.uk/
[i]This is the eye specialist and not the high street optician.
By Ms Kate Armon (Paediatric Rheumatologist) and NRAS
Original article: 12/01/2015
Next review due: 12/01/2018