Copper metabolism

Copper metabolism refers to the pathways and processes that enable the body to use copper, a key mineral that is crucial for maintaining human health. It involves the absorption, storage, and utilization of copper, as well as its excretion. Copper is essential for the functioning of several enzymes, the production of melanin, and the synthesis and maintenance of blood vessels, nerves, and bones. However, both copper deficiency and copper overload can lead to serious health issues.

Absorption and Transport

Copper is absorbed in the small intestine, particularly in the duodenum and jejunum. The process is regulated by a protein called Copper transporter 1 (CTR1), which controls the uptake of copper into the cells. Once inside the body, copper binds to various proteins, including albumin and transcuprein, which transport it through the bloodstream to the liver, the central organ for copper metabolism.

In the liver, copper is further processed and incorporated into enzymes or stored bound to metallothionein, a protein that helps regulate its concentration. The liver also synthesizes ceruloplasmin, the major copper-carrying protein in the blood, which transports copper to other parts of the body where it is needed.

Function

Copper is a cofactor for several essential enzymes, known as cuproenzymes. These include cytochrome c oxidase, which is vital for cellular energy production; lysyl oxidase, important for the synthesis and maintenance of connective tissue; dopamine β-hydroxylase, involved in the synthesis of neurotransmitters; and superoxide dismutase, which plays a critical role in antioxidant defense.

Copper is also involved in the formation of hemoglobin, the molecule in red blood cells that carries oxygen, and in the regulation of gene expression and brain development.

Homeostasis

The body maintains copper levels within a narrow range through a balance of absorption, utilization, and excretion. When copper intake is low, the body can increase absorption and decrease excretion to conserve copper. Conversely, when intake is high, absorption can be reduced, and excretion via bile is increased to prevent accumulation and toxicity.

Disorders of Copper Metabolism

Disorders of copper metabolism can lead to either copper deficiency or toxicity.

Copper Deficiency

Copper deficiency can result from inadequate dietary intake, malabsorption syndromes, or genetic conditions that affect copper transport. Symptoms may include anemia, bone abnormalities, fatigue, and compromised immune function. Severe deficiency can lead to neurological problems due to the role of copper in brain development and function.

Copper Toxicity

Copper toxicity can occur due to excessive dietary intake, but it is more commonly caused by genetic disorders such as Wilson's disease, which impairs the body's ability to excrete copper. Symptoms of toxicity include liver damage, neurological symptoms, and psychiatric problems.

Treatment

Treatment for copper metabolism disorders varies depending on whether the issue is deficiency or overload. Copper deficiency is treated with copper supplements and dietary changes to increase copper intake. For copper toxicity, treatment may involve chelation therapy to remove excess copper from the body, dietary modifications, and in some cases, liver transplantation.