Metanephrine (metadrenaline) is a metabolite of epinephrine (adrenaline) created by the action of catechol-O-methyl transferase on epinephrine. It is a commonly occurring, pharmacologically and physiologically inactive metabolite of epinephrine. The measurement of plasma free metanephrines is considered to be the best tool in the diagnosis of pheochromocytoma, a rare kind of adrenal medullary neoplasm. In adrenal chromaffin cells, leakage of norepinephrine and epinephrine from storage granules leads to the substantial intracellular production of the O-methylated metabolite metanephrine. In fact, the adrenals constitute the single largest source out of any organ system including the liver for circulating metanephrine. In humans, about 93 percent of circulating metanephrine is derived from catecholamines metabolized within adrenal chromaffin cells.

Androsterone sulfate is endogenous, naturally occurring steroid and the the most abundant 5 alpha-reduced androgen metabolite in serum. This steroid is formed from the reaction of sulfation of androsterone and can be desulfated back by the action of steroid sulfatase. It was also found significant and sodium-dependent organic anion transporter SOAT (SLC10A6)-mediated transport of Androsterone sulfate. There existed assumption that may be this steroid could be a marker of systemic 5 alpha-reductase activity, but that was not confirmed and thus androsterone sulfate cannot take into consideration as a marker of either adrenal androgen production or of hirsutism.

Guanosine 3′,5′-cyclic monophosphate (cGMP) is a cyclic nucleotide derived from guanosine triphosphate (GTP). Cyclic GMP is a cellular regulatory agent that acts as a second messenger. Its levels increase in response to a variety of signals (acetylcholine, insulin, oxytocin). cGMP is involved in the regulation of kinases G. cGMP binds to sites on the regulatory units of protein kinase G (PKG) and activates the catalytic units, enabling them to phosphorylate their substrates. cGMP is a common regulator of ion channel conductance, glycogenolysis, and cellular apoptosis. It also relaxes smooth muscle tissues. In blood vessels, relaxation of vascular smooth muscles lead to vasodilation and increased blood flow. cGMP is a secondary messenger in phototransduction in the eye. In the photoreceptors of the mammalian eye, the presence of light activates cGMP phosphodiesterase 5 (PDE5), which degrades cGMP. The sodium ion channels in photoreceptors are cGMP-gated, so degradation of cGMP causes sodium channels to close, which leads to the hyperpolarization of the photoreceptor's plasma membrane and ultimately to visual information being sent to the brain. Mutations in the cGMP phosphodiesterase cause defects in cGMP metabolism leading to retinal disease. Inhibition of cGMP degrading PDE5 by its selective inhibitor sildenafil induced migraine without aura in 10 of 12 migraine patients and in healthy subjects.

Dihydroandrostenedione (Androstanedione) is a steroid metabolite and a precursor of both testosterone and estrone normally produced by the adrenal gland and gonads and is converted to testosterone through the action of 17β-hydroxysteroid dehydrogenase, which is found in most body tissues. Androstenedione is also produced by some plants and has recently been marketed as a product for increasing blood testosterone concentrations to be used as a natural alternative to anabolic steroid use. However, androstenedione administration during resistance training did not significantly alter the serum testosterone concentration in normotestosterogenic young men. The increased muscle size and strength observed with resistance training were also not augmented with androstenedione administration. The use of androstenedione increased the serum concentrations of estradiol and estrone, suggesting an increased aromatization of the ingested androstenedione and/or testosterone derived from the exogenous androstenedione. The use of androstenedione was associated with decreased levels of HDL-C. These data provide evidence that androstenedione does not enhance adaptations to resistance training and may result in potentially serious adverse health consequences in young men.

Histamine is a depressor amine derived by enzymatic decarboxylation of histidine. It is a powerful stimulant of gastric secretion, a constrictor of bronchial smooth muscle, a vasodilator, and a centrally acting neurotransmitter. Phosphate salt of jistamine was used as a diagnostic aid for evaluation of gastric acid secretory function. In addition, this compound is used as a positive control in evaluation of allergenic (immediate hypersensitivity or "Type I") skin testing. In addition, histamine is being studied for treatment of multiple sclerosis. It was approved, that histamine physiological functions are mediated by four 7-transmembrane G protein-coupled receptors (H1R, H2R, H3R, H4R) that are all targets of pharmacological intervention. The receptors display molecular heterogeneity and constitutive activity. H1R antagonists are long known antiallergic and sedating drugs, whereas the H2R led to the development of H2R-antagonists that revolutionized stomach ulcer treatment. The H3R is an auto receptor and heteroreceptor providing negative feedback on histaminergic and inhibition on other neurons. The H4R occurs on immuncompetent cells and the development of anti-inflammatory drugs is anticipated.