What are the common forms of juvenile arthritis?
The most common form of Juvenile Arthritis is called juvenile idiopathic arthritis. This in-turn is further subdivided into 3 subgroups

             Polyarthritis (5 or more joints involved),
             Pauci-arthritis (< 5 joints involved) and
             Systemic onset disease (also called Still’s disease).

In these forms of arthritis, joint involvement, is the predominant mode of presentation. Low grade fever weight loss and loss of appetite can accompany the first 2 forms of arthritis. Still’s disease often presents with high grade swinging fever, short-lived reddish rash (often with the fever swing) and, in a proportion of patients, other organ involvement. Pleural effusion (fluid in the covering membranes of the lung), pericardial effusion (fluid in the covering membranes of the heart), Ascites (fluid in the covering membranes of the intestine), enlargement of the liver/spleen etc are the organ systems that can be involved.

Systemic lupus erythematosus is a form of arthritis characterized by high-grade fever, facial rash, loss of hair, oral ulcers and joint pains. Diagnosing this entity is important, as other system involvement is common and troublesome. Anemia, low platelet count with bleeding, neurological involvement and kidney involvement can occur.
Scleroderma is characterized by tightening of skin (fingers & generalized), Blue fingers especially when exposed to cold (called Raynaud’s), heart burn with or without difficulty in swallowing (due to involvement of the food pipe-esophagus) and joint pains. Lung involvement (called interstitial lung disease), pulmonary hypertension and rapid increase in blood pressure (called accelerated hypertension) are important complications of this condition.
Polymyositis / dermatomyositis are conditions characterized by inflammation in the muscles. Patients present with painful weakness in the muscles. In addition patients with dermatomyositis have a rash on the face, trunk and typically over the knuckles. Lung involvement (interstitial lung disease) can occur in a proportion of patients.

What is rheumatic fever?
This is a form of arthritis, which, occurs after specific streptococcal infection of the throat. It is characterized by fever, flitting and fleeting arthritis (completely improves in one joint before involving the other joint), erythematous rash (in some), subcutaneous nodules (in some) and inflammation of the heart or its covering membrane (pericarditis, myocarditis and endocarditis). It is this cardiac involvement which if not treated adequately leads to valvular involvement later. The short-lived joint involvement, propensity to involve the heart and its association with specific streptococcal throat infection differentiates this disorder from juvenile idiopathic arthritis described earlier. Hence this is an important disease to be excluded when a child presents with joint problems.

What to do when arthritis is suspected?
As and when your general practitioner suspects arthritis he would more often than not send you to a specialist who has experience in treating these disorders.

What would the specialist do?
After confirming the clinical suspicion, the specialist would organize relevant blood tests to diagnose the type of arthritis and the presence and absence of complications. After having assessed the investigations, the specialist would start treatment with appropriate medications.

What are the common investigations done in children with arthritis?
These may be divided into a few subgroups:
To assess disease activity: CBC, ESR & CRP are common tests done to assess activity.
To assess damage: Radiographs of relevant joints are done for this.
To assess for drug side effects: Routine tests (blood and other) are done on a regular basis to assess for side effects due to drugs.
To assess complication of the disease: Since these arthritis’ can affect other organ system, if a particular organ system is suspected to be affected, relevant investigations to assess that particular system.