Use

Human growth hormone (GH) exists in several isomeric forms in serum, either free or bound to a specific binding protein (GH‑BP). This protein is identical to extracellular domain of the GH receptor on the cell membrane. Level of GH‑BP varies with age, being low in neonates and highest in young adults. Normal or elevated levels in patients with classical Laron syndrome indicate a defect in the transmembrane, intracellular or post‑translational GH receptor domains. Very low or absent GH‑BP denotes a defect in the extracellular domain. A low GH‑BP in relatives of patients with Laron syndrome helps identify heterozygous carriers of patients with defects in the extracellular domain.