Human growth hormone (HGH) stimulates growth and production of cells in the body. The pituitary gland in the human brain is responsible for secreting this complex hormone. It consists of 191 amino acids. HGH is the largest protein created by the pituitary gland. Pituitary gland secretes HGH throughout one’s childhood. It is produced the most during the adolescent stage. The human body continues to produce HGH even after the adolescent stage. But as one grows older, the production of HGH by the pituitary gland declines. This is where HGH supplements comes in handy. The main function of this hormone is to increase muscle mass and body height. It helps to retain calcium, maintain healthy bones, reduce fat, control sugar and insulin levels and maintain immunity. Some studies even suggest it can make one look younger. Due to these benefits, there is an increasing demand for HGH supplements. And just like any other product, when there is a high demand, there is an increasing supply to meet it. While many HGH products have hit the market in recent years, a number of them should be avoided. This is why it is important to look for high quality HGH products. When quality is mentioned with regards to HGH, one very important element comes up; purity. So does purity determine the quality of HGH? Well, let us take an in-depth look at the relationship between the purity and the quality of HGH. Does purity determine the quality of HGH? The purity of an HGH product directly determines its quality. This means that an HGH product is considered to be of high quality only when it has a high purity level. HGH can be made up of either 191 amino acids (known as somatropin), or 192 amino acids (known as somatrem). The former is the real product sequence while the latter is basically an HGH mimic with comes with nasty side effects. The high purity HGH (high quality) is much costlier compared to the low purity products which are cheaply produced and have bacterial residues left over during the manufacturing process. High quality products are often bought through doctors’ prescriptions. So avoid buying your HGH supplement on the black market as most of the products are counterfeit and may have nasty side effects. Moreover, they will not deliver the kind of result that you are looking for. If you have to buy from a non-reputable source, then it is advisable to have the HGH tested in a lab. Some of the most expensive brands of HGH are products manufactured in the US. One example of such products is the Genotropin, manufactured in the US by Pfizer Inc. This high quality and high purity HGH is one of the most effective and most expensive brands in the market. There are also medium purity and medium quality HGH products such as Hygetropin manufactured in China by Zhongshan Hygene Biopharm Co., Ltd. If you are looking for cheaper brands, there are a few choices available to you such as Zomacton and Ansomone. However, most of these brands are of low quality. While such these brands may be effective, there is limited information or user feedback to back their reliability or safe use.