Información del artículo
Los factores de crecimiento similares a la insulina (IGF, de insulin-like growth factors) son unos péptidos estructuralmente relacionados con la insulina, que tienen acción estimuladora del crecimiento, potencian la acción de la insulina y regulan la proliferación celular. Aunque la expresión de IGF es ubicua, la mayor parte del IGF circulante es de origin hepático. Parece ser que una de las principales funciones del IGF-I circulante es el retrocontrol inhibitorio de la secreción de somatotropina, tanto hipofisaria como hipotalámica. En el plasma y en los fluidos biológicos, las IGF circulan unidas en su mayor parte a proteínas transportadoras de alta afinidad, las insulin-like growth factor binding proteins (IGFBP) que modulan su vida media, su interacción con el receptor y posiblemente desempeñen acciones directas en la proliferación celular. A estas proteínas, junto a los propios IGF y sus receptores, se les engloba actualmente en el llamado sistema IGF, que tiene una gran trascendencia en el crecimiento y la diferenciación de células normales y malignas. La determinación de los diferentes componentes del sistema IGF tiene gran utilidad en el diagnóstico y la monitorización del tratamiento en pacientes con alteraciones del eje GH-IGF. En este artículo se revisarán los aspectos preanalíticos y analíticos que deben conocerse para la correcta interpretación de los resultados.
Palabras clave:
Factores de crecimiento similares a la insulina
IGF-I
IGF-II
Proteínas enlazantes de los factores de crecimiento similares a la insulina
IGFBP-3
Subunidad acidolábil
Métodos de laboratorio
Condiciones preanalíticas
Insulin-like growth factors (IGFs) are peptides which are structurally related to insulin and which stimulate growth,enhance the action of insulin, and regulate cell proliferation. Although IGF expression is ubiquitous, most circulating IGF is produced in the liver. One of the main functions of circulating IGF-I is to exercise inhibitory feedback on growth hormone (GH) secretion, in both the pituitary gland and hypothalamus. In plasma and biological fluids, IGFs mainly circulate together with insulin-like growth factor binding proteins (IGFBPs), which modulate their half-life and interaction with the receptor and possibly exert direct actions on cell proliferation. These proteins,together with IGFs and their receptors, are currently included under the term IGF system, which is of great importance in the growth and differentiation of both normal and malignant cells. Determination of the distinct components of the IGF system is highly useful in the diagnosis and monitoring of treatment in patients with alterations in the IGF-GH axis. The present article reviews the preanalytical and laboratory features that should be known for correct interpretation of results.
Key words:
Insulin-like growth factors
IGF-1
IGF-II
Insulin-like growth factor binding proteins
IGFBP-3
Acid-labile subunit
Laboratory methods
Preanalytical conditions
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