If your doctor suspects you have arthritis, he or she may have your blood drawn to determine which type of arthritis you have. In people with osteoarthritis, blood tests are not usually abnormal, but with other types of arthritis, including rheumatoid arthritis, certain tests will help your doctor decide which type you have.

This article reviews the different types of blood tests and markers used to diagnose arthritis and other inflammatory-related conditions.

RAtv from WebMD

Video: See Flo Fight Her RA

See How Karate Helped Flo Fight Back Against RA

Video: Top Rheumatologist Explains RA

Video: What Is RA?

What Blood Markers Are Used to Diagnose Rheumatoid Arthritis?

Rheumatoid factors are a variety of antibodies that are present in 70%-90% of people with rheumatoid arthritis (RA). A low level of rheumatoid factor can be found in people without RA or with other autoimmune disorders, however. In general, when no rheumatoid factor is present in someone with RA, the course of the disease is less severe. A new test for rheumatoid arthritis that measures levels of antibodies that bind citrulline modified proteins (anti-CCP) is more specific and tends to be only elevated in patients with rheumatoid arthritis or in patients about to develop rheumatoid arthritis. The presence of anti-CCP antibodies can be used to predict which patients will get more severe rheumatoid arthritis.

Are There Tests to Determine Inflammation?

Yes. The erythrocyte sedimentation rate (sed. rate or ESR) is an indication of the degree of inflammation in the body. It is actually a measurement of the speed with which red blood cells fall in a test tube of blood. When the inflammation in the blood goes up, these inflammatory substances attach to red blood cells and the cells fall faster. In healthy persons, the sed. rate is low and it climbs with inflammation. It doesn't point to any particular disease, but is a general indication of the amount of inflammation in the body. In lupus and polymyalgia rheumatica, the ESR often correlates with disease activity.

C-reactive protein (CRP) also indicates the amount of inflammation present. It is thought to be a better test than the sed. rate. In patients with rheumatoid arthritis, if the CRP is high, it suggests that there truly is significant inflammation or injury in the body.

Both CRP and ESR levels are used to monitor disease activity and how well someone is responding to treatment.

What Signs Indicate Connective Tissue Disorders like Lupus?

The ANA is a blood test that is used in the evaluation of possible lupus or other connective tissue disorders. When the ANA is positive, it indicates that someone may have an autoimmune disorder, but alone it can't make the diagnosis.

The ANA profile is a series of tests consisting of an ANA and other related antibodies. This may be done if the ANA is found to be positive or possibly at the same time as the ANA. This profile helps look for diseases such as Sjögren's syndrome, lupus and drug-induced lupus.

1 | 2

Next Page >

WebMD Medical Reference provided in collaboration with the Cleveland Clinic

Rheumatoid Arthritis Guide

Overview & Facts

Symptoms & Types

Diagnosis & Tests

Treatment & Care

Home Remedies

Finding Help

Do You Have Fibromyalgia Pain?

Cymbalta is approved for the management of fibromyalgia.

Important Safety Information

Cymbalta^® (duloxetine HCl) is approved for the treatment of depression and generalized anxiety disorder, and for the management of diabetic peripheral neuropathic pain and fibromyalgia.

What should I talk about with my healthcare provider?

Patients on antidepressants and their families or caregivers should watch for new or worsening depression symptoms, unusual changes in behavior, thoughts of suicide, anxiety, agitation, panic attacks, difficulty sleeping, irritability, hostility, aggressiveness, impulsivity, restlessness, or extreme hyperactivity. Call your healthcare provider right away if you have thoughts of suicide or if any of these symptoms are severe or occur suddenly. Be especially observant within the first few months of antidepressant treatment or whenever there is a change in dose.

You should also know that:

Suicide is a known risk of depression and some other psychiatric disorders.
Antidepressants may increase suicidal thoughts or behaviors in some children, adolescents, and young adults especially within the first few months of treatment or when changing the dose. No increased risk has been shown for adults over age 24, and risk decreased for those over age 65.
All patients starting therapy should be monitored appropriately and observed closely for new or worsening depression symptoms, suicidal thoughts or behavior, or unusual changes in behavior.
Cymbalta^® is not approved for use in patients under age 18.

Who should NOT take Cymbalta?
You should not take Cymbalta if:

You have recently taken a type of antidepressant called a monoamine oxidase inhibitor (MAOI)
You have uncontrolled narrow-angle glaucoma (an eye disease)
You are taking Mellaril^® (thioridazine)

What other important information should I discuss with my healthcare provider?
Before starting Cymbalta, tell your healthcare provider:

about all of your medical conditions, including kidney problems, glaucoma, or diabetes
about your alcohol use
if you are taking nonprescription or prescription medicines, including those for migraine, to address a possible life threatening condition
if you are taking NSAID pain relievers, aspirin, or blood thinners. Use with Cymbalta may increase bleeding risk
if you are pregnant, plan to become pregnant during therapy, or are breastfeeding an infant

While taking Cymbalta, tell your healthcare provider:

if you have itching, right upper belly pain, dark urine, yellow skin/eyes, or unexplained flu-like symptoms, which may be signs of liver problems. Severe liver problems, sometimes fatal, have been reported
if you have high fever, confusion, and stiff muscles to address a possible life-threatening condition
before stopping Cymbalta or changing your dose
if you experience dizziness or fainting upon standing, especially when first starting Cymbalta or when increasing the dose. Your healthcare provider may periodically check your blood pressure while you are taking Cymbalta

If you have any questions, talk to your healthcare provider before taking Cymbalta.

What are the possible side effects of Cymbalta?

The most common side effect of Cymbalta was nausea. For most people who had it, the nausea was mild to moderate. Other common side effects included dry mouth, sleepiness, constipation, decreased appetite, and, increased sweating. This is not a complete list of side effects.

Safety Information and Boxed Warning | Prescribing Information | Medication Guide