page_title: Saliva testing
section_title: Sensitivity and specificity
hierarchical_section_title: Saliva testing / Selected criticism / Sensitivity and specificity
caption_attribution_description: English: Sex hormone-binding globulin Polski: Struktura białka wiążącego hormony płciowe
context_page_description: Saliva testing or Salivaomics is a diagnostic technique that involves laboratory analysis of saliva to identify markers of endocrine, immunologic, inflammatory, infectious, and other types of conditions. Saliva is a useful biological fluid for assaying steroid hormones such as cortisol, genetic material like RNA, proteins such as enzymes and antibodies, and a variety of other substances, including natural metabolites, including saliva nitrite, a biomarker for nitric oxide status.
  Saliva testing is used to screen for or diagnose numerous conditions and disease states, including Cushing's disease, anovulation, HIV, cancer, parasites, hypogonadism, and allergies. Salivary testing has even been used by the U.S. government to assess circadian rhythm shifts in astronauts before flight and to evaluate hormonal profiles of soldiers undergoing military survival training.
  Proponents of saliva testing cite its ease of collection, safety, non-invasiveness, affordability, accuracy, and capacity to circumvent venipuncture as the primary advantages when compared to blood testing and other types of diagnostic testing.
context_section_description: One often cited criticism of using saliva as a diagnostic fluid is that biomarkers are present in amounts that are too low to be detected reliably. As Wong points out, however, this “is no longer a limitation” due to the development of increasingly sensitive detection techniques. Advances in ELISA and mass spectrometry, in addition to the emergence of novel detection methods that take advantage of nanotechnology and other technologies, are enabling scientists and practitioners to achieve high analyte sensitivity.
  Biomarker specificity is another consideration with saliva testing, much as it is with blood or urine testing. Many biomarkers are nonspecific (for example, CRP is a nonspecific inflammatory marker), and thus they can not be used alone to diagnose any particular disease. This issue is currently being addressed through identification of multiple biomarkers that are correlative of a disease; these can then be screened concomitantly to create a comprehensive panel of tests that significantly increases diagnostic specificity. Of note, certain types of saliva testing are considered by many to be more specific than blood testing; this is particularly true for steroid hormones. Since salivary hormone tests measure only those hormones that are not bound to sex hormone-binding globulin (SHBG) or albumin, they are regarded as reflecting only the bioactive (“free”) fraction. With continued research into the field of salivary testing, accuracy parameters such as sensitivity and specificity will continue to improve.
caption: A three-dimensional structure of the "sex hormone-binding globulin (SHBG)".
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