Gold (197 a.m.u.) not a vital element, but could manifest biological activity regarding some ferments. Concentration of gold is human body is lower than 10 mg, 50% of it in bones.

Metallic gold is an inert metal. Metallic gold and alloys thereof are used in instrument engineering, space and electronic industries, jewelry. In medicine gold agents are being used for rheumatoid arthritis treatment, radioactive gold – in treatment of some types of growth, metallic gold and alloys – in dentistry.

Toxic effects of gold are mostly linked with overdosing or adverse events after using its salts for rheumatoid arthritis treatment. To achieve therapeutic benefits of gold agents in cases of rheumatoid arthritis, a specific amount of feeding and long-lasting supporting treatment with therapeutic level over 100 – 200 mcg of gold /dl of serum is required. Different tissues are accumulating gold in different amount. Traces of gold could be manifesting in serum for 10 months after therapy.

The most frequent manifest of gold agents’ toxicity is dermatitis with eosinophilia. In addition to allergic reactions, adverse events could include autoimmune reactions, toxic effect on kidneys and liver and damage of hematopoiesis system. There is no direct correlation reported between therapeutic doses, concentration of gold in urine and serum and clinical effects, but skin allergic reactions were mostly reported for patients with higher concentration of this element in blood. Mechanisms of toxic effect of gold are being linked with gold thiol groups and inhibition of thiol-containing ferments.