In order to measure the concentration of hGH in the sample; this human hGH ELISA kit includes a set of calibration standards (6 standards). The calibration standards are assayed at the same time as the samples and allow the operator to produce a standard curve of Optical Density (O.D.) versus GH concentration (ng/mL). The concentration of hGH in the samples is then determined by comparing the O.D. of the samples to the standard curve. The microtiter plate provided in this human GH ELISA kit has been pre-coated with a monoclonal antibody specific to hGH. Standards or samples are then added to the microtiter plate wells and incubated. After wash all wells, hGH if present, will bind to the antibody pre-coated on the wells. In order to quantitatively determine the amount of hGH present in the sample, a standardized preparation of horseradish peroxidase (HRP)-conjugated polyclonal antibody specific to hGH is added to each well to “sandwich” the hGH immobilized on the plate. The microtiter plate undergoes incubation, and then the wells are thoroughly washed to remove all unbound components. Next, a TMB (3,3', 5,5' Tetramethyl-benzidene) substrate solution is added to each well. This enzyme (HRP) and substrate are allowed to react over a short incubation period. Only those wells that contain hGH and enzyme-conjugated antibody will exhibit a change in colour. The enzyme-substrate reaction is terminated by the addition of a sulphuric acid solution and the colour change is measured spectrophotometrically at a wavelength of 450 nm.

This hGH ELISA kit is calibrated against NIBSC/WHO, 98/574, hGH. In this hGH ELISA kit, no hook effect is observed. Each laboratory must establish its own normal range based on patient population. The wash procedure is critical. Insufficient washing will result in poor precision and falsely elevated O.D. readings. This human GH ELISA kit is to be used for the in vitro quantitative determination of human growth hormone (hGH) concentrations in serum. This human GH ELISA kit is intended FOR LABORATORY RESEARCH USE ONLY, and is not to be used in diagnostic or therapeutic procedures.

Several molecular forms of GH circulate. Much of the growth hormone in the circulation is bound to a protein (growth hormone binding protein, GHBP) which is derived from the growth hormone receptor. GH is secreted into the blood by the somatotrope cells of the anterior pituitary gland, in larger amounts than any other pituitary hormone. Secretion levels are highest during puberty. The transcription factor PIT-1 stimulates both the development of these cells and their production of GH. Failure of development of these cells, as well as destruction of the anterior pituitary gland, results in GH deficiency.

The major isoform of the human growth hormone is a protein of 191 amino acids and a molecular weight of about 22,000 daltons. The structure includes four helices necessary for functional interaction with the GH receptor. GH is structurally and apparently evolutionarily homologous to prolactin and chorionic somatomammotropin. Despite marked structural similarities between growth hormone from different species, only human and primate growth hormones have significant effects in humans.

Effects of growth hormone on the tissues of the body can generally be described as anabolic (building up). Like most other protein hormones GH acts by interacting with a specific receptor on the surface of cells. GH directly stimulates division and multiplication of chondrocytes of cartilage. These are the primary cells in the growing ends (epiphyses) of children's long bones (arms, legs, digits). GH also stimulates production of insulin-like growth factor 1 (IGF-1, formerly known as somatomedin C), a hormone homologous to proinsulin.The liver is a major target organ of GH for this process, and is the principal site of IGF-1 production. IGF-1 has growth-stimulating effects on a wide variety of tissues. Additional IGF-1 is generated within target tissues, making it apparently both an endocrine and an autocrine/paracrine hormone. IGF-1 also has stimulatory effects on osteoblast and chondrocyte activity to promote bone growth.