Evidence-Based Supplement & Herb Guides

Procalcitonin Test: Bacterial Infection, Sepsis Risk, High Levels, and Interpretation

Learn how the procalcitonin test supports bacterial infection and sepsis assessment, what high and low levels mean, and how trends can guide antibiotics.

A procalcitonin (PCT) test measures a protein in blood that often rises during a significant systemic bacterial infection. Healthy people usually have very low...

Serum Amyloid A (SAA) Test: Acute Inflammation, High Levels, and Disease Activity

Learn what a serum amyloid A test measures, why SAA rises in acute inflammation, how it tracks disease activity, and when persistent elevation raises AA amyloidosis concern.

Serum amyloid A (SAA) is a group of acute-phase proteins that can rise sharply when the body responds to infection, tissue injury, or inflammatory...

White Blood Cell (WBC) Count Test: High Levels, Infection, Inflammation, and Causes

Understand what a WBC count measures, why white blood cells rise with infection, inflammation, stress, medicines, or blood disorders, and how results are evaluated.

A white blood cell (WBC) count measures the total number of leukocytes circulating in a blood sample. These immune cells help identify and respond...

Activated T-Cell Marker Test: HLA-DR, CD38, Immune Activation, and Inflammation

Learn how HLA-DR and CD38 flow cytometry measures activated T cells, what high results may mean, why ranges vary, and how clinicians plan follow-up.

An activated T-cell marker test uses flow cytometry to estimate how many T lymphocytes are showing signs of recent or ongoing stimulation. Laboratories may...

B-Cell Count Test: CD19, CD20, Immune Function, and Antibody Production

Understand how CD19 and CD20 B-cell counts are measured, why results may be high or low, how anti-CD20 therapy affects them, and which follow-up tests assess antibody function.

A B-cell count test measures the number and percentage of B lymphocytes in blood, usually by flow cytometry. Laboratories most often identify B cells...

CD4 Count Test: Helper T Cells, Immune Function, HIV Monitoring, and Meaning

Learn what a CD4 count measures, how HIV affects helper T cells, what common ranges and thresholds mean, why results fluctuate, and how the test guides monitoring and infection prevention.

A CD4 count measures helper T cells, a group of lymphocytes that coordinate immune responses against infections and support B cells, macrophages, and cytotoxic...

CD4/CD8 Ratio Test: Immune Balance, High and Low Ratio, and Meaning

Learn how the CD4/CD8 ratio is calculated, what low or high results may mean, why an inverted ratio is nonspecific, and how the test adds context in HIV and immune monitoring.

The CD4/CD8 ratio compares helper T cells with cytotoxic T cells in a blood sample. It is calculated by dividing the absolute CD4 count...

CD8 Count Test: Cytotoxic T Cells, Immune Function, and Viral Response

Learn what a CD8 count measures, why cytotoxic T-cell numbers may rise or fall, how viral infections affect results, and why cell quantity does not equal antiviral function.

A CD8 count measures a major group of T lymphocytes involved in recognizing and removing virus-infected, damaged, or abnormal cells. The cells are often...

Chemokine Panel Test: Immune Signaling, Inflammation, and Cell Migration Markers

Understand what a chemokine panel measures, why immune-signaling and cell-migration markers rise or fall, and how specialists interpret patterns and limitations.

A chemokine panel measures several small immune-signaling proteins that help direct white blood cells toward infection, injury, tumors, or inflamed tissue. Unlike a routine...

Cytokine Panel Test: IL-1, IL-6, IL-8, TNF-Alpha, Interferon-Gamma, and Immune Activation

Learn what a cytokine panel measures, how IL-1, IL-6, IL-8, TNF-alpha, and interferon-gamma patterns are interpreted, and why results require clinical context.

A cytokine panel measures a group of proteins that immune and tissue cells use to communicate. Common targets include interleukin-1 beta, interleukin-6, interleukin-8, tumor...

Cytokine Storm Blood Test Panel: IL-6, Ferritin, CRP, D-Dimer, and Severe Inflammation

Understand how IL-6, ferritin, CRP, D-dimer, blood counts, and clotting tests help evaluate cytokine storm, CRS, HLH, MAS, and severe inflammation.

A “cytokine storm blood test panel” is not one standardized laboratory test. It is a group of tests used to look for severe, dysregulated...

Flow Cytometry Immune Panel: Lymphocyte Markers, Immune Cells, and Immune Deficiency

Learn how a flow cytometry immune panel counts T cells, B cells, and NK cells, what abnormal patterns may mean, and why function, age, and context matter.

A flow cytometry immune panel identifies and counts immune-cell populations by detecting markers on or inside individual cells. A basic lymphocyte panel usually reports...

Granulocyte-Macrophage Colony-Stimulating Factor (GM-CSF) Test: Immune Activation and Inflammation

Understand what a GM-CSF test measures, why high or low levels are difficult to interpret, and how anti-GM-CSF antibodies differ in pulmonary alveolar proteinosis.

A granulocyte-macrophage colony-stimulating factor test measures GM-CSF, also called CSF2, in blood or another specimen. GM-CSF is a cytokine that helps myeloid cells—including monocytes,...

Interferon-Alpha Test: Antiviral Immune Activity and Inflammation Meaning

Understand what an interferon-alpha test measures, why IFN-α or interferon signatures may be high or low, and how specialists interpret antiviral and inflammatory results.

An interferon-alpha test looks at one part of the body’s early antiviral defense system. Interferon-alpha, usually written IFN-α, is a family of type I...

Interferon-Gamma Test: Immune Activation, Infection Response, and T-Cell Activity

Learn how serum interferon-gamma tests, IFN-γ release assays, and anti-IFN-γ antibody tests differ, and what high, low, positive, or indeterminate results may mean.

An interferon-gamma test can mean several different laboratory procedures, and the distinction changes the interpretation. Interferon-gamma, or IFN-γ, is a cytokine made mainly by...

Interleukin-1 Beta (IL-1β) Test: Inflammation, Immune Activation, and Autoinflammatory Disease

Learn what an IL-1β test measures, why levels may be high or undetectable, how inflammasomes release IL-1 beta, and how specialists evaluate autoinflammatory disease.

An interleukin-1 beta test measures a powerful inflammatory cytokine, but it is not a general-purpose test that can diagnose inflammation by itself. Interleukin-1 beta,...

Interleukin-2 (IL-2) Test: T-Cell Activation, Immune Response, and Meaning

Understand what an IL-2 test measures, why serum and stimulated results differ, what high or low values may mean, and which immune tests provide useful follow-up.

An interleukin-2 (IL-2) test measures a cytokine that activated T cells release to coordinate immune-cell growth, survival, and regulation. Although IL-2 is often described...

Interleukin-4 (IL-4) Test: Allergy, Th2 Immune Response, and Immune Signaling

Understand what an IL-4 test measures, how it relates to Th2 immunity, allergy, asthma, and eczema, and why high or low results need method-specific clinical interpretation.

An interleukin-4 (IL-4) test measures a cytokine central to type 2 immunity, the immune program involved in defense against parasites, tissue repair, antibody class...

Interleukin-5 (IL-5) Test: Eosinophilic Inflammation, Allergy, Asthma, and Meaning

Learn what an IL-5 test measures, how it relates to eosinophils, asthma, allergy, and eosinophilic disease, and why high or low results require clinical context.

An interleukin-5 (IL-5) test measures a cytokine that promotes eosinophil development, survival, activation, and movement from bone marrow into blood and tissues. IL-5 is...

Interleukin-6 (IL-6) Test: High Levels, Inflammation, Cytokine Activity, and Immune Response

Understand what an IL-6 test measures, why levels rise in infection and inflammation, how timing and treatment affect results, and which follow-up tests add clinical meaning.

An interleukin-6 (IL-6) test measures a rapidly changing cytokine involved in infection defense, inflammation, antibody responses, blood-cell production, metabolism, and tissue repair. IL-6 can...