An ACTH blood test measures adrenocorticotropic hormone, a pituitary hormone that helps regulate cortisol. Learn why it’s ordered, how to prepare, what high or low results may mean, and why results are usually interpreted with cortisol testing.
A quantitative hCG blood test measures the exact amount of human chorionic gonadotropin in blood. Learn what it can and cannot tell you, how to prepare, how results are interpreted, when repeat testing matters, and what to consider about cost.
An H. pylori blood test looks for antibodies to Helicobacter pylori, but it cannot reliably prove active infection. Learn what results mean, how to prepare, when breath or stool testing is better, and what to ask next.
A Lyme disease blood test looks for antibodies to Borrelia bacteria, not the tick-borne bacteria itself. Learn how two-tier testing works, when results are reliable, what IgM and IgG mean, and what to ask your clinician after a positive, negative, or equivocal result.
A CMV blood test checks for evidence of cytomegalovirus infection, usually with IgG and IgM antibodies or, in higher-risk patients, CMV DNA by PCR. Learn what the test measures, how to prepare, how results are interpreted, and when follow-up testing may be needed.
An EBV blood test checks for antibodies to Epstein-Barr virus, a common cause of mono. Learn what VCA IgM, VCA IgG, EBNA, Early Antigen, and Monospot results can and cannot tell you.
A hepatitis B blood test can show current infection, past infection, vaccine immunity, or susceptibility. Learn what HBsAg, anti-HBs, anti-HBc, IgM anti-HBc, and HBV DNA mean.
An HIV blood test checks for signs of HIV infection using antibodies, p24 antigen, or viral RNA. Learn which test is usually ordered, when to test after exposure, how to prepare, what results mean, and how cost and privacy work.
A rheumatoid factor blood test measures RF autoantibodies that can be associated with rheumatoid arthritis, Sjögren disease, chronic infections, and other conditions. Learn what the test can and cannot tell you, how to prepare, and what positive, negative, and borderline results may mean.
An ANA blood test looks for antinuclear antibodies that may be seen in lupus and other autoimmune conditions. Learn what positive, negative, titer, and pattern results mean—and what to ask next.
