Rheumatoid Factor Test

Rheumatoid factor test is used to measure the amount of rheumatoid factor in the blood. Rheumatoid factors are proteins produced by the body's immune system that can attack healthy tissue in the body. Antibodies are normal protein found in the blood, functioning within the immune system. Rheumatoid factor is an immunoglobulin i.e. antibody that can bind other antibodies. It may be present in 1-2% of the healthy population. In older people aged 65 and above, 20% have elevated level of rheumatoid factor.

Elevated levels of rheumatoid factor in the blood show up as autoimmune diseases, such as rheumatoid arthritis and Sjogren's syndrome. Many a time, rheumatoid factor may be detected in few healthy people and at times some people with autoimmune diseases have normal levels of rheumatoid factor. Patients with negative rheumatoid factor but suffering from the condition are classified as having seronegative rheumatoid arthritis. But largely, healthy people do not produce rheumatoid factor.

A sample of blood is drawn from the vein in the arm and sent to the laboratory for test. The RF test helps to diagnose rheumatoid arthritis and may also help the physician choose the line of treatment. A positive result, i.e. test result indicating the presence of rheumatoid factor in the blood may confirm rheumatoid arthritis in a person. About 80% of adults who have rheumatoid arthritis test high for rheumatoid factor.

This test helps differentiate between rheumatoid and inflammatory arthritis from other types of arthritis. High level of rheumatoid factor may also result from the presence of other autoimmune diseases in the body such as:

• Cancer
  
• Cirrhosis
  
• Scleroderma
  
• Sjogren's syndrome
  
• Chronic infections
  
• Mixed connective tissue disease
  
• Inflammatory lung disease like Sarcoidosis
• Systemic lupus erythematosus
  

When is the test ordered?

Rheumatoid factor test is ordered for persons suffering from the following symptoms:

• Stiffness in the joints
  
• Increased pain in the joints in the morning
  
• Bone loss
  
• Loss of cartilage
  
• Nodules under the skin
  
• Warmth and swelling in the joints.

Rheumatoid arthritis test principle

Rheumatoid factor can be identified in the laboratory by its ability to bind and form clumps with latex particles or red blood cells that have human immunoglobulin (IgG). If the patient being tested has rheumatoid factor, then it attaches to the IgG coating the latex particles causing lumps. This process is called agglutination. Agglutination is a positive reaction that indicates the presence of rheumatoid factor at a detectable level.

Rheumatoid Factor Results

The antibody titer is a test that measures the quantity of the blood that can be diluted before RF antibodies become indistinguishable. The following results will be considered as normal:
Less than 40 - 60 units/ml
Less than 1:80 (1 to 80) titer.

A low number (normal result) generally indicates that the person being tested does not have rheumatoid arthritis or Sjogren syndrome. However, a few people who have the condition may still have a normal or low rheumatoid factor (RF). Normal ranges may vary from laboratory to laboratory.

An abnormal result may mean the test is positive. Most patients with this result may have rheumatoid arthritis or Sjogren's syndrome. The higher the level, the more likely the condition is present. There are other tests that may be used to diagnose the condition.

• False positive results can occur when the fat content in the blood is high.
  
• Inaccurate results may show up when the blood specimen is handled improperly.
  
• A negative rheumatoid factor does not rule out the presence of rheumatoid arthritis.
  

Animal Bites

Animal bites are one of the most reported causalities with adults and children. In addition to the emergency measures to stop bleeding in the event of an animal bite, physicians need to look for potential pathogens such as bacteria or virus that can cause further damage to the patient.

Dog and cat bite

It is one of the common forms of animal bites. A dog that attacks or bites has pre-existing tendency of abnormal temperament, which triggers its proactive nature to bite an individual. However, dogs, which are kept as pets that have been vaccinated, are not dangerous when they leave minor scratches with their teeth. Dogs, which are affected by rabies, are more dangerous and can be lethal. An attack by a rabid dog can be traumatizing leading to many physiological and psychological conditions. Immunoglobulin and anti-rabies vaccines are given immediately to the victim to prevent the multiplication of the rabies virus. If ignored, rabies virus can be fatal causing adverse complications such as hydrophobia and sometimes death. Similar approach is taken with respect to cats. In case of cat scratch, immunoglobulin along with antimicrobial such as tetracycline are used to prevent associated bacterial infections caused by Pasteurella and Bartonella species.

Rodent bites

Rodent bites are rare but are equivalently dangerous as they are potential carriers of rabies virus along with bacterial species such as Leptospira and streptobacillus SP. In the event of a rodent bite, immediate medical attention is required. The proximity of the bite region to the brain is very significant as it is associated with the rapid propagation the virus.

Reptile bites

The most common form of reptile bites is snakebites. These bites are fatal and require immediate medical attention. Snake bites are widely studied and depending upon the type of snake and the potential venom it produces, the anti-venom is administered. Some snakes such as the black mamba and Cobra seen in Africa and Asia produce venom that is neurotoxic. Other snakes such as vipers, rattle snakes and kraits produce venom that is toxic to the circulatory system. Anti-venom administration is followed by patient observation for a period of 24 hours is essential to ensure positive prophylaxis.

In addition, other animals such as raccoons, coyotes, foxes, skunks which fall under the wild mammal categories are also treated with anti-rabies vaccines and tetanus shots.

Management of animal bites

Animal bites have to be effectively analyzed in order to manage them well. The history and the demography of the animal are recorded along with appearance and behavior traits. Evidence-based conclusions are drawn to confirm that the animal especially if it's a mammal is rabid. All wounds have to be cleaned thoroughly to prevent cross infection and sepsis. All puncture wounds ranging from mild to severe have to be treated with respective vaccines and antimicrobial drugs. The most common drugs used are Augmentin, tetracycline, clindamycin and in some cases cefuroxime and metronidazole. This prevents the onset of tissue necrosis by the bacteria. Azithromycin is recommended in case of cat scratch as it prevents the growth of Bartonella.

Multiple sclerosis

Multiple sclerosis or MS is an autoimmune disease that occurs when the myelin sheath that protects nerve cells is damaged. This leads to slowing of nerve impulses. Inflammation along the brain, optic nerve or spinal cord leads to nerve damage.

Those who have a family history of MS are more susceptible to this condition. The symptoms appear in episodes that relapse after days or weeks or even months. The episodes might be triggered by stress or fever.

Symptoms of Multiple sclerosis appear all over the body as they affect nerve cells. There is numbness and loss of balance, tremors in arms or legs, muscle spasms and difficulty in walking. There is an overriding feeling of fatigue. Patients suffering from MS might have eye discomfort with double vision or loss of vision. There might be painful spasms in the facial muscles and stool or urine leakage. The person might experience depressive feelings, slurred speech and difficulty in swallowing.

MS is diagnosed through brain MRI and spinal MRI. Spinal tap of cerebrospinal fluid is done to check for Multiple sclerosis. Medications to reduce the degradation caused by MS include interferon, Methotrexate, azathioprine (Imuran), intravenous immunoglobulin (IVIg) and cyclophosphamide (Cytoxan). Speech therapy and occupational therapy helps the patients to a large extent.