Renin is an enzyme produced by the kidney that can raise blood pressure levels. The renin activity plasma test helps your doctor determine whether or not your high blood pressure is due to poor kidney health.

The reptilase clotting time measures the rate of fibrin clot formation after the addition of reptilase, a proteolytic enzyme derived from the venom of Bothrops atrox, to citrated plasma.

Reptilase is a thrombin-like enzyme. 

Unlike thrombin, which cleaves fibrinogen to produce fibrinopeptides A and B, reptilase cleaves the fibrinogen molecule to release only fibrinopeptide A.

This section explores the presence and abundance of a panel of antibiotic resistance genes in the gut microbiome, and compares that to healthy population. The resistome is the sum of antimicrobial resistance genes in your gut. High number of resistance functions in your gut will make pathogens less likely to be sensitive to antibiotics and may be an indication that virulent strains are flourishing.

Reticulocyte Hemoglobin Equivalent (Retic Hgb Equivalent) is an invaluable marker in hematology, gaining prominence for its role in assessing iron status and erythropoiesis in clinical settings. This marker measures the hemoglobin content in reticulocytes, which are immature red blood cells recently released from the bone marrow. Retic Hgb Equivalent provides critical insights into the iron available for new red blood cell production, making it a vital tool for diagnosing and managing iron deficiency anemia and other disorders of red blood cell production.

Reticulocytes are newly produced, relatively immature red blood cells (RBCs). A reticulocyte test determines the number and/or percentage of reticulocytes in the blood and is a reflection of recent bone marrow function or activity.

Reticulocyte hemoglobin (Ret-He) is a crucial indicator in hematology, measuring hemoglobin in immature red blood cells, or reticulocytes. It's pivotal for diagnosing and managing anemia, especially iron deficiency anemia. Ret-He offers an early sign of iron deficiency, aiding in prompt intervention. This measure is more dynamic than traditional markers like serum ferritin, reflecting real-time iron availability for red blood cell production. Its inclusion in modern blood count analyzers underscores its importance in accurate diagnosis and patient care in iron-related disorders.

Reticulocytes are red blood cells that are still developing. They are also known as immature red blood cells. Reticulocytes are made in the bone marrow and sent into the bloodstream. About two days after they form, they develop into mature red blood cells. These red blood cells move oxygen from your lungs to every cell in your body.

RBP is a sensitive marker of undernutrition and the monitoring of its serum concentration allows the monitoring of nutritional status.

Retinol-binding protein (RBP) is an unglycosylated protein synthesised by the liver. The role of RBP is to transport retinol (vitamin A) from the liver to the target tissues (retina, skin, etc.) in the bloodstream. This protein is then metabolized, filtered and reabsorbed in the kidney.

Reverse T3 is a biologically inactive thyroid hormone; however, it does block the conversion of thyroxine (T4) to triiodothyronine (T3). Higher levels of reverse T3 can decrease the effect of thyroid hormone.

RF, IgA by EIA (RDL) refers to the measurement of rheumatoid factor (RF) of the IgA subclass using an enzyme immunoassay (EIA), typically performed at RDL (Reference Diagnostic Laboratory). RF is an autoantibody directed against the Fc portion of immunoglobulin G (IgG) and is commonly associated with rheumatoid arthritis (RA) and other autoimmune conditions. While IgM-RF is the most commonly tested form, IgA-RF may provide additional diagnostic value, particularly in seronegative RA or cases with extra-articular manifestations. Elevated IgA-RF levels have been linked to more severe joint damage and systemic inflammation, and they may correlate with disease activity in rheumatoid arthritis and other autoimmune disorders. This test is typically used alongside other serological markers like IgM-RF, anti-CCP antibodies, and inflammatory markers to improve diagnostic accuracy and assess disease progression.

RF, IgG by EIA (RDL) refers to the measurement of rheumatoid factor (RF) of the IgG class using enzyme immunoassay (EIA) at RDL (Rheumatology Diagnostic Laboratory). Rheumatoid factor is an autoantibody that targets the Fc region of IgG, and its presence is often associated with autoimmune conditions, particularly rheumatoid arthritis (RA) and other inflammatory diseases. While RF is most commonly measured as IgM, the IgG RF subtype can also contribute to disease mechanisms, including immune complex formation and chronic inflammation. Elevated IgG RF levels may indicate rheumatoid arthritis, Sjögren’s syndrome, or other connective tissue diseases, but can also be found in some infections and chronic inflammatory states. Since RF alone is not diagnostic, it is typically interpreted alongside other markers, such as anti-CCP antibodies, ESR, and CRP, to assess autoimmune disease activity.

RF, IgM by EIA (RDL) is a laboratory test that measures rheumatoid factor (RF) of the IgM class using enzyme immunoassay (EIA) methodology. RF is an autoantibody that targets the Fc region of IgG antibodies and is commonly associated with autoimmune conditions, particularly rheumatoid arthritis (RA). Elevated RF IgM levels can indicate inflammatory or autoimmune diseases, including Sjogren’s syndrome, systemic lupus erythematosus (SLE), and other connective tissue disorders. However, RF can also be detected in some healthy individuals or those with chronic infections, making it important to interpret results alongside clinical symptoms and other diagnostic markers. The RDL designation refers to the reference diagnostic laboratory performing the test, ensuring standardized measurement and reliability.

What is the Rheumatoid factor (RF) test?

The rheumatoid factor (RF) test is a blood test that's often used to help diagnose rheumatoid arthritis (RA). The test measures the amount of RF in your blood.

What is the Rheumatoid factor?

The rheumatoid factor (RF) is an autoantibody that is formed in people who have rheumatoid arthritis. It is a protein made by your immune system. High levels of RF in your blood indicate that you may have an autoimmune disease such as RA or Sjögren's syndrome. However, not everyone who tests positive for RF has RA.

RF can also be found in a small percentage of healthy people, particularly aging individuals.

Rheumatoid Factor (RF) is an autoantibody often found in individuals with autoimmune diseases, most notably rheumatoid arthritis (RA). It targets the Fc region of immunoglobulin G (IgG), forming immune complexes that contribute to inflammation and tissue damage. Detecting RF is crucial for diagnosing and monitoring autoimmune disorders.

One of the methods for measuring RF is Turbidimetric Rheumatoid Factor Detection (Turb RDL). This technique uses turbidimetry, a method that measures the cloudiness or turbidity in a solution caused by antigen-antibody complexes. When RF is present in the serum sample, it reacts with specific antigens, creating immune complexes. These complexes scatter light, and the degree of scattering is directly proportional to the concentration of RF in the sample. The higher the RF levels, the more turbid the solution becomes.