A preliminary diagnosis for musculoskeletal disease can be made after obtaining a history of present illness and examining painful areas of a patient’s body. On many occasions only a laboratory examination of bodily fluids and tissues, Imaging or Electrodiagnostic testing can reveal disease not detected during physical exam. Laboratory tests are useful to confirm a diagnosis, monitor disease progress, evaluate for medication effectiveness, or determine if the drugs used to treat a condition are putting a person at risk for potentially dangerous – but not yet evident – side effects. Blood tests can also help a physician determine if a patient’s painful musculoskeletal condition is related to their work or a disease the patient has acquired by genetic predisposition or a past illness.

The majority of lab tests are performed on blood; it is easily and safely sampled and it provides useful information as to what’s going on throughout the body. Other tests may require urine, joint fluid, or biopsy of skin / muscle.

Routine tests useful for confirming a specific diagnosis for musculoskeletal pain:

• Comprehensive metabolic panel (CMP) – this is a group of tests that are utilized to help evaluate extent of tissue damage and monitor kidney / liver function while a patient is being treated with potentially harmful medication.

• CBC – this test is used to evaluate blood cell status. Physicians can monitor the effect of disease and treatment on blood cell production and blood loss. Gastrointestinal bleeding is one of the most common side effects from taking potentially harmful medications such as steroids and NSAID’s.

• Erythrocyte sedimentation rate – Also called ESR or “sed rate,” this test measures how fast red blood cells cling together, fall and settle (like sediment) in the bottom of a glass tube over the course of an hour. This test shows the presence of inflammation in the body and the activity of the disease. It is used to help diagnose RA and to evaluate and monitor the condition. ESR will be increased in RA but not in osteoarthritis.

• C-reactive protein (CRP) – this test also indicates inflammation and tests for the activity of the disease. It may be used to help diagnose RA and to evaluate and monitor the condition. An increased level of CRP occurs in RA but not in osteoarthritis.

• Rheumatoid factor (RF) – Designed to detect and measure the level of an antibody that acts against the blood component gamma globulin, this test is often positive in people with rheumatoid arthritis.

• Cyclic citrullinated peptide (CCP) antibody – may be used to help diagnose RA, especially early in the disease – potentially before symptoms even appear – and in people who are RF-negative; found in 60-70% of people with RA; when used with the RF test, CCP results can help confirm a diagnosis of RA.

• Antinuclear antibody (ANA) – Commonly found in the blood of people who have lupus, ANAs (abnormal antibodies directed against the cells’ nuclei) can also suggest the presence of polymyositis, scleroderma, Sjogren’s syndrome, mixed connective tissue disease or rheumatoid arthritis. Tests to detect specific subsets of these antibodies can be used to confirm the diagnosis of a particular disease or form of arthritis.

• Anti-DNA / Anti-Sm  - Luupus patients have antibodies to the heredity material DNA (deoxyribonucleic acid). It is a useful diagnostic tool since it is unusual to find these antibodies in people who do not have lupus. The test is also a good monitoring tool since the levels of anti-DNA rise and fall with disease activity.Lupus patients  have antibodies to Sm, another substance in the cell's nucleus. These antibodies also occur only in lupus patients. The test is not useful in monitoring disease activity.

• HLA tissue typing – This test, which detects the presence of certain genetic markers in the blood, can often confirm a diagnosis of ankylosing spondylitis (a disease involving inflammation of the spine and sacroiliac joint) or Reiter’s syndrome (a disease involving inflammation of the urethra, eyes and joints). The genetic marker HLA-B27 is almost always present in people with either of these diseases.

• Lyme serology – This test detects an immune response to the infectious agent that causes Lyme disease and thus can be used to confirm a diagnosis of the disease.

• Uric acid – By measuring the level of uric acid in the blood, this test helps doctors diagnose gout, a condition that occurs when excess uric acid crystallizes and forms deposits in the joints and other tissues, causing inflammation and severe pain.

• Creatine Kinase (CK) - is used to detect inflammation of muscles (myositis) or serious muscle damage and/or to diagnose rhabdomyolysis if a person has signs and symptoms, such as muscle weakness, muscle aches, and dark urine.

• Lactate Dehydrogenase LDH  - is most often measured to check for tissue damage. The protein LDH is in many body tissues, especially the heart, liver, kidney, muscles, brain, blood cells, and lung.

Other tests useful for making a pain diagnosis:

• Skin biopsy – Taking small samples of skin and examining them under a microscope can help doctors diagnose forms of arthritis that involve the skin, such as lupus, vasculitis (inflammation of the blood vessels) and psoriatic arthritis.

• Muscle biopsy – By going a little deeper into the tissue than with the skin biopsy, the surgeon can take a sample of muscle to be examined for signs of damage to the muscle fibers. Findings can confirm a diagnosis of polymyositis or vasculitis.

• Joint fluid analysis – In this procedure, which is similar to drawing blood, the doctor inserts a needle into a joint space and removes fluid. An examination of the fluid may reveal uric acid crystals, confirming a diagnosis of gout or bacteria, suggesting that the joint inflammation is caused by infection.

Non-Laboratory tests                                

• X-ray and CT scans – used to help diagnose musculoskeletal disease and monitor joint damage. Studies will not usually show significant changes early in the disease; can be used to rule out other causes of joint and bone pain.
• Ultrasound and MRI – may be used to help detect changes in the nerves, vessels, ligaments, tendons, muscles, joints and bones earlier in the disease process.
• Electromyography / Nerve Conduction Study (EMG/NCS) - may be used to detect changes in the peripheral nerves, muscles and central nervous system early in the disease process. The studies can assist physicians in determining the location and extent of disease and are able differentiate problems arising from muscle, peripheral nerves, spinal cord and brain.