What Are Arthritis Blood Tests?

What are Arthritis Blood Tests? Let’s discuss this. Blood is fluid circulating in our bodies all the time, providing oxygen and nutrients to organs while taking away waste materials. 

Many proteins in the form of mediators, hormones, and many other forms circulate with blood. 

We don’t need to test for only pathological molecules. Instead, many physiological molecule levels rise during a disease that can be measured through a blood test to diagnose the disease.

Similar is the case with arthritis, and the following test can be done to detect it. 

Here is a related article that might interest you on Best Cars For Seniors With Arthritis 2022.

What Are Arthritis Blood Tests?

Complete Blood Count (CBC)

CBC is generally considered a baseline test, and most of the time, doctors write this up. This test is a simple one but can detect many diseases. Also, it measures many proteins and blood cell levels in our body, telling us about average well-being. It tells us the levels of red blood cells, White blood cells, Haematocrit, Haemoglobin, and Platelets.

To detect an abnormality, it’s imp first to know the average values, which are

• Red blood cells:3.93-5.69 million/mm³
• White blood cells: 4.5-11.1  thousand/mm³
• Haematocrit: Men, 13.2-17.3 g/ dL
•                      Women,34%-46%

• Haemoglobin: Men,13.2-17.3 g/dL

                     Women, 11.7-16.1 g/dL

• Platelets: 150-450 thousand/mm³

This will help your doctor diagnose any pathology, rule out other differential diagnoses, and monitor medications and their possible side effects like anaemia. Usually, typical arthritis like rheumatoid arthritis doesn’t alter the levels of blood cell lines, but other similar conditions can, so it will help rule them out.

ANA or Antinuclear Antibody

Ana or antibodies are not generally found in the body; instead, they are produced in the body under certain conditions such as lupus, scleroderma, and even rheumatoid arthritis.

They are produced by the immune system and attack the body’s healthy tissues, which makes them a sensitive marker for any autoimmune disease.

This test is not specific as it’s used for many autoimmune diseases but is a sensitive test for arthritis. This is why it’s a screening test and not a diagnostic test.

The test has been positive in almost all SLE (Systemic lupus erythematosus) patients, which’s a complication of lupus arthritis.

Although the ANA test can be positive in many other conditions, like Sjogren syndrome, and Raynaud’s phenomenon, most of the time. 

ANA test alone can’t be used to make a diagnosis. These test measurements are taken in titter A ratio is calculated by comparing the solution with the antibodies. A ratio of 1:40 means 1 ANA antibody in 40 parts of a solution, which is a negative test.

This investigation will help eliminate lupus, scleroderma, and Sjögren’s syndrome.

Rheumatoid Factor or RF

RF is a protein generated by the body’s immune system that circulates and attacks healthy cells. As the name suggests, a factor will be found in patients who are positive for rheumatoid arthritis.

Rheumatoid factor is also an antibody that targets blood gamma globulin. This test will be positive most of the time in patients having rheumatoid arthritis. It will be harmful to patients who have Psoriatic arthritis.

This makes it a diagnostic test to some extent for rheumatoid arthritis. Although some conditions can exhibit a positive RF and it’s also a fact that a patient can still have rheumatoid arthritis even tested negative for Rheumatoid factor.

The average value of RF is 0-20u/mL of blood, while in Rheumatoid arthritis, they can rise above 20 u/mL of blood.

People even without high RF can have rheumatoid arthritis and vice versa.

Other conditions such as prolonged Infections, Lupus, leukaemia, and cancer can cause high RF values and need to be differentiated based on other investigations.

Anti-Cyclic Citrullinated Peptide (Anti-CCP) 

It’s an auto-antibody (an abnormal protein attacking the body’s healthy tissues) produced by the body when there is inflammation going on in the body. It’s found in around 60-80% of people suffering from RA. This test, unlike other tests, will help detect rheumatoid arthritis initially or when it’s on the borderline.

It’s a much better, more viable test for rheumatoid arthritis in contrast to rheumatoid factor. Again not all Rheumatoid arthritis patients show up with Anti-CCP in their blood and might need other tests to rule out other conditions.

The average value of Anti-CCP is 20u/mL or less. It’s a susceptible test; if it’s positive, there is more than a 95% likelihood of having rheumatoid arthritis.

If anti-CCP comes positive, it might be a sign of severe rheumatoid arthritis, and a high value means increased folds of joint damage. This test only appears positive in rheumatoid arthritis.

Risk and damage multiply if both Anti-CCP and RF appear favourable. They remain negative in 20% of patients with arthritis.

Uric Acid levels

A uric Acid test is not directly done to rule out typical types of arthritis. It’s to detect whether the signs and symptoms occurring are due to gout or not. Uric acid levels are measured by taking a blood sample. Even if uric acid levels are high, arthrocentesis and radiological investigations can make a definite diagnosis.

HLA-B27 Typing 

This investigation is used for reactive arthritis specifically. It’s a genetic marker used to detect arthritis and ankylosing spondylitis. 

The level of HLA genes increases when a person is suffering from reactive arthritis.

HLA-B27 is present on the surface of white blood cells and this test measures this gene on WBCS. White ethnicity also usually has this gene, around 10%.

HLA-B27 is associated with many genetic conditions. These are classified under spondyloarthropathies. They attack the joints, cartilage tendons, and ligaments. The gene is also found in Juvenile arthritis and Reiter’s syndrome.

Erythrocyte Sedimentation Rate (ESR) 

ESR is known as an inflammatory marker. This is measured by injecting an anti-clotting factor into a test tube and adding blood. Red blood cells separate from other blood components, then the clumping of red blood cells is measured and how fast they sediment to the bottom of the container. It’s known as the Sed rate.

This test can tell us about the inflammation process in the body but will not be able to localise it or tell us about the cause which is leading to inflammation. Following are the values for knowing ESR normal and abnormalities.

• Men less than 50 years: 0-15 mm/h 
• Men more than 50 years : 0-20 mm/h
• Women less than 50years: 0-20 mm/h
• Women more than 50years: 0-30 mm/h
• In a healthy individual, ESR will be low. The reason it’s heavier in a person who has inflammation in the body is that inflamed cells are heavy, so they tend to fall. The higher the activeness of the disease will be the rate. 
• Several conditions cause high ESR Polymyalgia rheumatica vasculitis.
• This test is used for arthritis because this condition is known to accumulate inflammatory infiltration in the body. Although, it’s not the sole test used for the diagnosis of RA.
• An extremely high ESR means infection and not arthritis.

C-Reactive Protein (CRP)

CRP measures body inflammation by measuring CRP, a protein produced by the liver, and circulates in the blood.

CRP is released into the body in response to infection to trigger your immune system for a response. It’s not a specific diagnostic test; it’s used with other investigations to produce a diagnosis. Also, it is used to diagnose rheumatoid arthritis, psoriatic arthritis, and lupus.

• It’s less than 10 mg/L but varies for each person.
• CRP can act as a siren, as its levels go up even before a disease’s signs and symptoms appear.
• It’s helpful for doctors to find the disease early and monitor the progression and effects of medicines.
• Generally, it appears in all autoimmune diseases and infections.

Anti-dsDNA Test: 

This test is done for autoimmune disorders. It is usually done after a positive ANA test. It’s mainly diagnostic for SLE and used to monitor this disease.

Creatine kinase (CK)

Creatinine kinase is a biomarker for several diseases and is also used to monitor their progression. It’s measured by measuring creatinine phosphokinase or CPK levels. 

This might be a result of the muscular inflammation process.

• It can be done to eliminate other inflammatory conditions similar to arthritis signs and symptoms.
• It can be positive in lupus, heart attack, and muscular dystrophy.

Complement System

• The complement system works by activating and releasing chemical mediators responsible for the inflammatory process. In this process, several inflammatory proteins can be utilised. Below we will see the normal values of all proteins in a complement system:

• Serum CH50: 30-75 u/mL

• Serum C3:
  • Men: 88-252 mg/dL 
  • Women: 88-206 mg/dL
• Serum C4:
  • Men: 12-72 mg/dL
  • Women: 13-75 mg/dL

• Lower levels of all three proteins may signify lupus or simply vasculitis.
• This test will be conducted to eliminate other inflammation causes when the diagnosis is not precise.

Cryoglobulins

• These substances cling together in a cold environment and dissolve in hot temperatures. 
• There are Following three different  types of Cryoglobulins:

• Type I is seen in cancer.
• Type II saw with hepatitis C or viral infections.
• Type III is associated with autoimmune disease.
• It usually absent in a healthy person’s body.

In A Nutshell,

Arthritis is diagnosed clinically on different criteria drafted scientifically; these investigations are supporting evidence for diagnosis.

Also, you have to check out my post on How Can Arthritis Be Diagnosed?

Also, these tests are mainly done for screening purposes, to rule out other similar conditions, and for follow-up purposes.