Rheumatoid Factor (RF) IgA is an IgA-class autoantibody that targets the Fc region of other immunoglobulins, similar to RF IgG and IgM. While RF (IgM) is the most commonly tested marker for rheumatoid arthritis (RA), RF (IgA) may provide additional insights into disease severity, progression, and immune system activity.

Rheumatoid Factor (RF) IgG is an immunoglobulin G (IgG) autoantibody that targets the body’s own tissues, particularly the Fc region of other antibodies. While RF is commonly associated with rheumatoid arthritis (RA), its presence can also indicate other autoimmune conditions or chronic infections.

Rheumatoid Factor IgM (RF-IgM) is an antibody commonly measured to help diagnose rheumatoid arthritis (RA) and other autoimmune disorders. Rheumatoid factor is part of a group of antibodies that target the body's own tissues, often mistaking them for foreign invaders. Specifically, the IgM type of rheumatoid factor is the most commonly tested and can be found in the blood of many individuals with autoimmune diseases.

What does an equivocal result mean?

An "equivocal" result means the test result falls into a borderline or "gray area"—neither clearly positive nor clearly negative. This can happen when the measured levels of the biomarker (in this case, Rheumatoid Factor IgM) are slightly above normal but not high enough to be definitively considered positive.

In practice, an equivocal result suggests that:

1. Further Monitoring May Be Needed: The immune system could be fluctuating, so retesting after a few weeks or months might provide a clearer result.
2. Additional Testing Could Help: Equivocal results often lead doctors to order additional tests to gather more information, such as anti-CCP for rheumatoid arthritis or other autoimmune markers.
3. It May or May Not Indicate Disease: In some cases, an equivocal result could suggest a mild immune response or early-stage disease, but in others, it might simply be a variation with no clinical significance.

Doctors often evaluate equivocal results in the context of other symptoms and tests, using the full clinical picture to guide further diagnosis and treatment.

- Common in soil, plants, bathrooms, and in beverages like milk, juice, and water. 
- May be a commensal (=living in a relationship in which one organism derives food or other benefits from another organism without hurting or helping it). 
- Can cause disease in immunosuppressed patients.

Ri Antibody Screen with Reflex to Titer and Western Blot - Anti-Ri can be detected in patients with the paraneoplastic opsoclonus/myoclonus syndrome. Neoplasms most often associated with Anti-Ri include breast cancer, gynecological cancers, and small cell lung cancer.

Riboflavin, also known as Vitamin B2, is a water-soluble vitamin that plays a crucial role in energy production, cellular function, and metabolism. It is a component of two major coenzymes, flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), which are key players in the metabolism of carbohydrates, fats, and proteins, facilitating the production of energy (ATP) in the body. Riboflavin is also essential for the regeneration of glutathione, one of the body's main antioxidants, thus playing a significant role in protecting cells from oxidative stress and damage. Additionally, Vitamin B2 is involved in the conversion of other B vitamins, including niacin (B3) and pyridoxine (B6), into their active forms, making it essential for maintaining overall B vitamin metabolism. Its role extends to the development and function of the skin, lining of the digestive tract, blood cells, and many other parts of the body.

Anti-ribosomal P proteins antibody (anti-rib P) is a highly specific marker for systemic lupus erythematosus (SLE) and it is associated with liver involvement in this disease.

The presence of antibodies to Rice is an indication of food immune reactivity. The offending food and its known cross-reactive foods should be eliminated from the diet. Adverse reactions to Rice have been reported.

Despite its cross-reactivity to wheat, Rice is often over-consumed in a gluten-free diet, which can result in the patient developing an immune reactivity to Rice.

Elevated antibody levels can be clinically significant — while the antibodies themselves don’t destroy anything, they do trigger an inflammatory response that can cause significant destruction of tissue and resulting symptoms. This response is not necessarily dependent on antibody levels. However, an equivocal result may mean you are just beginning to exhibit an immune reaction, so this is an important time to take measures to support the body in damping immune reactivity.

Rickettsia typhi is the etiological agent of murine typhus. R. typhi is transmitted primarily by the rat flea, Xenopsylla cheopis. Lice and mites can be potential vectors and rodents, shrews, opossums, cats can be reservoir. The clinical manifestations of murine typhus are usually less severe than those of epidemic typhus and includes persistent headache, a high-grade fever, and a cutaneous rash predominating on the trunk. Murine typhus usually takes a prolonged incubation period and the characteristic rash is occasionally absent. An antibody response is usually detected only after 10 days from the onset of systemic symptoms, and antibody titers reach a peak after 3 to 4 weeks or later if an antibiotic therapy has been administered.

The Right Coronary Artery (RCA) is a pivotal vessel in the cardiovascular system, playing a central role in the assessment of heart health during a Coronary Calcium Scan. This scan, utilizing computed tomography (CT) technology, is designed to detect the presence of calcium deposits within the coronary arteries, indicative of atherosclerotic plaque. The RCA originates from the right aortic sinus and courses along the right atrioventricular groove, supplying blood to the right atrium, right ventricle, part of the left ventricle, the sinoatrial (SA) node in most individuals, and the atrioventricular (AV) node. The presence of calcification in the RCA, as revealed in the scan, signifies the extent of coronary artery disease (CAD) in this vessel.

The Ristocetin Cofactor (RCoF) test is a critical diagnostic assay used to measure the functional activity of von Willebrand factor (vWF), a protein essential for blood clotting. This test plays a key role in diagnosing and managing von Willebrand disease (VWD), the most common inherited bleeding disorder. By assessing how well vWF promotes platelet aggregation in the presence of ristocetin, the RCoF test provides a quantitative measure of vWF function. It is highly specific for detecting dysfunctional vWF (e.g., in type 2 VWD) and is often paired with vWF antigen testing to differentiate between quantitative and qualitative defects. The test is also used to monitor treatment efficacy, assess surgical bleeding risks, and detect acquired von Willebrand syndrome. While factors like blood type, stress, or pregnancy can influence results, advances such as automated assays and recombinant ristocetin analogs have improved accuracy and efficiency, solidifying the RCoF test as an indispensable tool in hematology.

Rocky Mountain spotted fever (RMSF) can be difficult to diagnose due to the non-specific signs and symptoms in early stages of illness. Signs and symptoms can vary from patient to patient and can resemble other, more common diseases. Nonetheless, early consideration of rickettsial disease in the differential diagnosis and empiric treatment is crucial to prevent severe illness and death.