Antibody adrenocorticotropic hormone

FIGURE 23-3 Radioimmunoassay (RIA). (a) A low concentration of radiolabeled hormone (red) is incubated with (T) a fixed amount of antibody specific for that hormone or (2) a fixed amount of antibody and various concentrations of unlabeled hormone (blue). In the latter case, unlabeled hormone competes with labeled hormone for binding to the antibody the amount of labeled hormone bound varies inversely with the concentration of unlabeled hormone present, (b) A radioimmunoassay for adrenocorticotropic hormone (ACTH). A standard curve of the ratio [bound] to [unbound radiolabeled ACTH] vs. [unlabeled ACTH added] is constructed and used to determine the amount of (unlabeled) ACTH in an unknown sample. If an aliquot containing an unknown quantity of unlabeled hormone gives, say, a value of 0.4 for the ratio [bound]/[unbound] (see arrow), the aliquot must contain about 20 pg of ACTH. 

With the introduction and use of monoclonal antibodies, the measurement of hormones is now accurate and precise. The production of hormones in cancer involves two separate routes. First, the endocrine tissue that normally produces it can produce excess amounts of a hormone. Second, a hormone may be produced at a distant site by a non-endocrine tissue that normally does not produce the hormone. The latter condition is called ectopic syndrome. For example, the production of adrenocorticotropic hormone (ACTH) is norraotopic by the pituitary and is ectopic by the small cell of the lung. Consequently, elevation of a given hormone is not diagnostic of a specific tumor, because a hormone may be produced by a variety of cancers. 

Adrenal angiography Adrenal venography Adrenocorticotropic hormone stimulation test Aldosterone assay, blood Androstenedione Antidiuretic hormone Antithyroglobulin antibody Antithyroid microsomal antibody Blood glucose Calcitonin Calcium Catecholamines Chromosome karyotype Computed tomography of adrenals Cortisol blood urine C-peptide... 

Acetylcholine receptor antibody Acid phosphatase Activated clotting time (ACT) Adrenocorticotropic hormone stimulation test Agglutinins, febrile/cold AIDS serology Alanine aminotransferase Aldolase... 

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