The immunoradiometric assay (IRMA).

Radionuclide testing of blood, urine, saliva, stool, spinal liquid, аscitic fluid and pleural liquids are convenient because they are performed in a test tube and completely exclude radiation exposure on an individual. They have received the greatest distribution in endocrinology for defining of concentration of hormones, enzymes, medical products, etc. The method uses competitive linkage stable and similar on chemical and biological properties labeled substances (labeled compounds) or combinations with specific connecting systems as reaction antigen-antibody. Therefore such evaluations have received the name of immunoradiometric assay, see fig.9.12.

Fig.9.12 The sketch of the immunoradiometric assay.

IRMA is used in endocrinology for defining of concentration of hormones (insulin, thyroxin, thyrotrophic hormone (ТТH), etc.), in allergology - for defining Ig E, in cardiology - for defining of myoglobin, in oncology - for defining of cancer-embryonic antigen (CEA), alpha-fetoprotein, chorionic gonadotrophin (CGT), in pediatrics - for defining of somatotropic hormone (SТH) and thyrotropic hormone (ТТH), in toxicology - for study medical products.

From the point of view of clinical value, radionuclide tests can be divided into four groups:

1) Completely provide an establishment of the diagnosis (disease of a thyroid gland, metastases to the skeleton, etc.);

2) Definition of infringement of function of the organ or system as a result on the basis of which the plan of the subsequent evaluation is developed (definitions of function of kidneys, hepato-biliar systems, etc.);

3) Establish anatomic-topographical features of structure and arrangement of internal organs (scanning, scintigraphy, SPECT, PET);

4) Enable to receive the additional diagnostic information in complex with clinico-instrumental evaluation with the purpose to define final diagnostic conclusion (evaluation of lungs, heart, a brain, etc.).

Indications for application of different methods of radio testing are determined by the attending physician who also makes algorithm of radio tests individually for each patient. Depending on the clinical case, radio testing should be begun with techniques in which ionizing radiation is not used, and if necessary - apply techniques in which ionizing radiation is used for the fullest expected diagnostic information

Depending on the purpose of test RND are divided into static and dynamic.

Static tests are able to give data about anatomic-topographical features (the form, the sizes, position) of the investigated body or system on character of distribution and accumulation of RPhP. Evaluation is carried out on scintyscaners, gamma-ray chambers, SPECT and PEТ.

Indications for carrying out of static evaluations: definitions of topography of internal organs and bodies, volume and level of their loss, diagnostics of volumetric formations.

Dynamic evaluations are fulfiled for study a functional condition of organs and systems in dynamics of moving RPhP. Evaluation carries out on radiometers, radiographs, gamma-ray chambers, SPECT and PET.

Indications for carrying out of dynamic evaluations: defining the degree of disfunction of organs and systems

Дата добавления: 2015-10-23