Seronegative

Seronegative is an adjective used in medicine to describe the absence of detectable specific antibodies in the blood serum against a defined antigen or pathogen, as determined by serological testing. The term is relative to the particular antibody test being used, and a patient may be seronegative for one pathogen but seropositive for another.

In rheumatology, seronegative refers to diseases in which the characteristic autoantibodies are not present. For example, seronegative rheumatoid arthritis describes rheumatoid arthritis in which rheumatoid factor (RF) and anti-cyclic citrullinated peptide (anti-CCP) antibodies are not detected. Seronegative spondyloarthropathies include conditions such as ankylosing spondylitis, psoriatic arthritis, and reactive arthritis, which typically lack RF.

In infectious disease, seronegative status can occur when antibodies have not yet formed after infection (window period), in individuals who cannot mount a robust antibody response (immunocompromised), or when the pathogen does not reliably induce a detectable antibody response. HIV testing often includes RNA or p24 antigen testing to identify infection during the early seronegative window period.

Seronegativity can be influenced by assay sensitivity, stage of disease, and individual variation. A seronegative result does not rule out disease; clinical assessment and possibly repeat testing or alternative diagnostic modalities may be necessary.

Related terms include seropositive, serology, seroconversion, and serological testing.