[Psoriasis: A general disease? Can psoriasis be explained biochemically?].

The biochemical problems of psoriasis are discussed, especially two modern hypothesis about the pathogenesis of this skin disease. 1. DHEA-deficiency leading to an increase of G-6-PDH inaugurated by Holzmann et al. 2. cAMP deficiency in psoriatic lesions as a cause of psoriasis hypothized by Voorhees and Duell. A synopsis of the physiology of the steroid hormone DHEA (synthesis, regulation, conjugation and excretion) is given. There are doubts that this hypothesis is correct. Recent findings have indicated, that there is no decrease of cAMP in the psoriatic lesion--in contrast there is an increase of this cyclic nucleotid. It means that this theory is also doubtfull. Treatment of an hypothetical decrease of cAMP by AMP is not possible, because this AMP will not penetrate in the cell and cannot be metabolized to cAMP.