Blood tyrosine determination for monitoring glucocorticoid therapy

Abstract

Glucocorticoid (GC) preparations are used in medicine for more than 70 years as the most powerful anti-inflammatory drugs also possessing immunosuppressive, anti-allergic, and antitoxic properties. However, administration of these unique preparations is associated with nearly inevitable severe adverse effects and a difficulty of their withdrawal. These adverse effects are caused not by toxicity of GC preparations, but are manifestations of their hormonal features. GC preparations are synthetic analogs of GC hormones which directly or indirectly participate in the regulation of virtually all reactions and processes in the body. Nevertheless, in clinical practice there is no index of tissue provision with GCs and real need in these hormones (or preparations). In this paper, blood tyrosine level was shown to characterize the tissue provision with GCs on two models: adrenalectomy in rats and the replacement GC therapy in congenital adrenal hyperplasia. Determination of blood tyrosine level made it possible to reveal the insufficiency of tissue provision with GGs in patients with bronchial asthma during the period of attacks. In patients with systemic lupus erythematosus, GC preparations were shown to be favorable on the background of increased blood tyrosine, i.e. on the insufficient tissue provision with GCs, and until the normalization of blood tyrosine, i.e. until the compensation of the hormonal insufficiency. On the background of normal blood tyrosine GC preparations in SLE were ineffective and side effects appeared rapidly. These observations allowed me to propose blood tyrosine level as a laboratory parameter for monitoring GC therapy. The present paper consists of two parts: I) short reviews of the literature prerequisites for the proposal; II) the description of the author’s studies on blood tyrosine behavior in comparison with delivery and efficiency of glucocorticoid hormones or preparations in experiment (adrenalectomy in rats) and in some pathologies: congenital adrenal hyperplasia, bronchial asthma, and systemic lupus erythematosus.