In addition to estrogen decay, and modify the OPG production parameter following . derives an alternate formulation for remodeling altogether to simplify the mass action kinetics models proposed by and . Estrogen changes are represented by a hyperbolically scaled estrogen term that modulates the RANKL state variable. In contrast, includes a thorough method section and model analysis and provides their source code. They model estrogen as an age-dependent concentration with a characteristic time scale of menopause onset that is fit to clinical data. This model also considers how estrogen alters sclerostin levels.