Copper deficiency | |
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Other names | Hypocupremia |
Ring Sideroblast smear, a sign of copper deficiency in the blood. | |
Specialty | Endocrinology |
Risk factors | Alcoholism, gastric bypass surgery |
Copper deficiency, or hypocupremia, is defined either as insufficient copper to meet the needs of the body, or as a serum copper level below the normal range. [1] Symptoms may include fatigue, decreased red blood cells, early greying of the hair, and neurological problems presenting as numbness, tingling, muscle weakness, and ataxia. [2] The neurodegenerative syndrome of copper deficiency has been recognized for some time in ruminant animals, in which it is commonly known as "swayback". [3] Copper deficiency can manifest in parallel with vitamin B12 and other nutritional deficiencies. [2]
The most common cause of copper deficiency is a remote gastrointestinal surgery, such as gastric bypass surgery, due to malabsorption of copper, or zinc toxicity. On the other hand, Menkes disease is a genetic disorder of copper deficiency involving a wide variety of symptoms that is often fatal. [4]
Copper is required for the functioning of many enzymes, such as cytochrome c oxidase, which is complex IV in the mitochondrial electron transport chain, ceruloplasmin, Cu/Zn superoxide dismutase, and in amine oxidases. [3] These enzyme catalyze reactions for oxidative phosphorylation, iron transportation, antioxidant and free radical scavenging and neutralization, and neurotransmitter synthesis, respectively. [3] Diets vary in the amount of copper they contain, but may provide about 5 mg/day, of which only 20-50% is absorbed. [2] The diet of the elderly may have a lower copper content than the recommended daily intake. [2] Dietary copper can be found in whole grain cereals, legumes, oysters, organ meats (particularly liver), cherries, dark chocolate, fruits, leafy green vegetables, nuts, poultry, prunes, and soybean products like tofu. [5]
Copper deficiency can have many hematological consequences, such as myelodysplasia, anemia, low white blood cell count, and low count of neutrophils (a type of white blood cell that is often called "the first line of defense" of the immune system). [2]
The characteristic hematological (blood) effects of copper deficiency are anemia (which may be microcytic, normocytic or macrocytic) and neutropenia. [6] Thrombocytopenia (low blood platelets) is unusual. [2] [7]
The peripheral blood and bone marrow aspirate findings in copper deficiency can mimic myelodysplastic syndrome. [8] Bone marrow aspirate in both conditions may show dysplasia of blood cell precursors and the presence of ring sideroblasts (erythroblasts containing multiple iron granules around the nucleus). Unlike most cases of myelodysplastic syndrome, the bone marrow aspirate in copper deficiency characteristically shows cytoplasmic vacuoles within red and white cell precursors, and karyotyping in cases of copper deficiency does not reveal cytogenetic features characteristic of myelodysplastic syndrome. [6] [7]
Anemia and neutropenia typically resolve within six weeks of copper replacement. [8]
Copper deficiency can cause a wide variety of neurological problems including myelopathy, peripheral neuropathy, and optic neuropathy. [3] [7]
Copper deficiency myelopathy in humans was discovered and first described by Schleper and Stuerenburg in 2001. [9] They described a patient with a history of gastrectomy and partial colonic resection who presented with severe tetraparesis and painful paraesthesias and who was found on imaging to have dorsomedial cervical cord T2 hyperintensity. Upon further analysis, it was found that the patient had decreased levels of serum coeruloplasmin, serum copper, and CSF copper. The patient was treated with parenteral copper and the patient's paraesthesias did resolve. Since this discovery, there has been heightened and increasing awareness of copper-deficiency myelopathy and its treatment, and this disorder has been reviewed by Kumar. Patients typically present difficulty walking (gait difficulty) caused by sensory ataxia (irregular muscle coordination) due to dorsal column dysfunction [7] or degeneration of the spinal cord (myelopathy). [3] [10] Patients with ataxic gait have problems balancing and display an unstable wide walk. They often feel tremors in their torso, causing sideways jerks and lunges. [11]
In brain MRI, there is often an increased T2 signalling at the posterior columns of the spinal cord in patients with myelopathy caused by copper deficiency. [3] [7] [12] T2 signalling is often an indicator of some kind of neurodegeneration. There are some changes in the spinal cord MRI involving the thoracic cord, the cervical cord or sometimes both. [3] [7] Copper deficiency myelopathy is often compared to subacute combined degeneration (SCD). [10] Subacute combined degeneration is also a degeneration of the spinal cord, but instead vitamin B12 deficiency is the cause of the spinal degeneration. [3] SCD also has the same high T2 signalling intensities in the posterior column as copper deficient patient in MRI imaging. [12]
Another common symptom of copper deficiency is peripheral neuropathy, which is numbness or tingling that can start in the extremities and can sometimes progress radially inward towards the torso. [7] [13] In an Advances in Clinical Neuroscience & Rehabilitation (ACNR) published case report, a 69-year-old patient had progressively worsened neurological symptoms. [14] These symptoms included diminished upper limb reflexes with abnormal lower limb reflexes, sensation to light touch and pin prick was diminished above the waist, vibration sensation was lost in the sternum, and markedly reduced proprioception or sensation about the self's orientation. [14] Many people with the neurological effects of copper deficiency complain about very similar or identical symptoms as the patient. [3] [13] This numbness and tingling poses danger for the elderly because it increases their risk of falling and injuring themselves. Peripheral neuropathy can become very disabling leaving some patients reliant on wheelchairs or walking canes for mobility if there is a lack of correct diagnosis. Rarely can copper deficiency cause major disabling symptoms. The deficiency will have to be present for an extensive amount of time until such disabling conditions manifest.
Some patients with copper deficiency have shown signs of vision and color loss. [13] The vision is usually lost in the peripheral views of the eye. [13] The bilateral vision loss is usually very gradual. [13] [15] An optical coherence tomography (OCT) shows some nerve fiber layer loss in most patients, suggesting the vision loss and color vision loss was secondary to optic neuropathy or neurodegeneration. [13]
Bariatric surgery is a common cause of copper deficiency. [3] [6] Bariatric surgery, such as gastric bypass surgery, is often used for weight control of the morbidly obese. The disruption of the intestines and stomach from the surgery can cause absorption difficulties not only as regards copper but also for iron and vitamin B12 and many other nutrients. [3] The symptoms of copper deficiency myelopathy may take up to decades to develop.
Increased consumption of zinc is another cause of copper deficiency. [7] Zinc is often used for the prevention or treatment of common colds and sinusitis (inflammation of sinuses due to an infection), ulcers, sickle cell disease, celiac disease, memory impairment, and acne. [7] Zinc is found in many common vitamin supplements and is also found in denture creams. [7] [15] [16] Recently, several cases of copper deficiency myeloneuropathy were found to be caused by prolonged use of denture creams containing high quantities of zinc. [15] [16]
Metallic zinc is the core of all United States currency coins, including copper-coated pennies. People who ingest a large number of coins will have elevated zinc levels, leading to zinc-toxicity-induced copper deficiency and the associated neurological symptoms. This was the case for a 57-year-old woman diagnosed with schizophrenia. The woman consumed over 600 coins, and started to show neurological symptoms such as unsteady gait and mild ataxia. [17]
Menkes disease is a congenital disease that is a cause of copper deficiency. [4] [7] [18] Menkes disease is a hereditary condition caused by a defective gene involved with the metabolism of copper in the body. [7] Menkes disease involves a wide variety of symptoms including floppy muscle tone, seizures, abnormally low temperatures, and a peculiar steel color hair that feels very rough. [4] [18] Menkes disease is usually a fatal disease with most children dying within the first ten years of life. [4] [18]
It is rarely suggested that excess iron supplementation causes copper deficiency myelopathy. [3] Another rarer cause of copper deficiency is celiac disease, probably due to malabsorption in the intestines. [3] Still, a large percentage, around 20%, of cases have unknown causes. [3]
Copper functions as a prosthetic group, which permits electron transfers in key enzymatic pathways like the electron transport chain. [3] [2] [19] Copper is integrated in the enzymes cytochrome c oxidase, which is involved in cellular respiration and oxidative phosphorylation, Cu/Zn dismutase, which is involved in antioxidant defense, and many more listed in the table below. [2]
Group | Enzyme | Function |
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Oxidases | Flavin-containing amine oxidase | Metabolism of neurotransmitters: noradrenaline, dopamine, serotonin and some dietary amines |
Protein-lysine-6-oxidase (lysyl oxidase) | Connective tissue synthesis- cross-linking of collagen and elastin | |
Copper-containing amine oxidase (a family of enzymes which includes primary-amine oxidase and diamine oxidase) | Oxidation of biogenic amines including neurotransmitters, histamines, putrescine, cadaverine, and xenobiotic amines | |
Cytochrome c oxidase | Oxidative phosphorylation, electron transport in the mitochondrial membrane | |
Superoxide dismutase (Cu/Zn dismutase) | Antioxidant and free radical scavenger, oxidizes dangerous superoxides to safer hydrogen peroxide | |
Ferroxidase I (ceruloplasmin) | Iron transport-oxidation of Fe2+ to Fe3+, copper storage and transport, antioxidant and free radical neutralizer | |
Hephaestin (ferroxidase) | Iron transport and oxidation of Fe2+ to Fe3+ in intestinal cells to enable iron uptake | |
Monooxygenases | Dopamine beta-monooxygenase | Conversion of dopamine to norepinephrine |
Peptidylglycine monooxygenase | Peptide hormone maturation- amidation of alpha-terminal carboxylic acid group of glycine | |
Monophenol monooxygenase (Tyrosinase) | Melanin synthesis | |
Methylation Cycle | Methionine synthase | Transfer of methyl group from methyltetrahydrofolate to homocysteine to generate methionine for the methylation cycle and tetrahydrofolate for purine synthesis |
Adenosylhomocysteinase (S-Adenosyl-L-homocysteine) | Regeneration of homocysteine from adenosylhomocyesteine (S-Adenosyl-L-homocysteine) in the methylation cycle |
There have been several hypotheses about the role of copper and some of its neurological manifestations. Some suggest that disruptions in cytochrome c oxidase, also known as Complex IV, of the electron transport chain is responsible for the spinal cord degeneration. [3] [10]
Another hypothesis is that copper deficiency myelopathy is caused by disruptions in the methylation cycle. [10] The methylation cycle causes a transfer of a methyl group (-CH3) from methyltetrahydrofolate to a range of macromolecules by the suspected copper dependent enzyme methionine synthase. [10] This cycle is able to produce purines, which are a component of DNA nucleotide bases, and also myelin proteins. [10] The spinal cord is surrounded by a layer of protective protein coating called myelin (see figure). When this methionine synthase enzyme is disrupted, the methylation decreases and myelination of the spinal cord is impaired. This cycle ultimately causes myelopathy. [10]
The anemia caused by copper deficiency is thought to be caused by impaired iron transport. Hephaestin is a copper containing ferroxidase enzyme located in the duodenal muscosa that oxidizes iron and facilitates its transfer across the basolateral membrane into circulation. [6] Another iron transporting enzyme is ceruloplasmin. [6] This enzyme is required to mobilize iron from the reticuloendothelial cell to plasma. [6] Ceruloplasmin also oxidizes iron from its ferrous state to the ferric form that is required for iron binding. [4] Impairment in these copper dependent enzymes that transport iron may cause the secondary iron deficiency anemia. [6] Another speculation for the cause of anemia is involving the mitochondrial enzyme cytochrome c oxidase (complex IV in the electron transport chain). Studies have shown that animal models with impaired cytochrome c oxidase failed to synthesize heme from ferric iron at the normal rate. [6] The lower rate of the enzyme might also cause the excess iron to clump, giving the heme an unusual pattern. [6] This unusual pattern is also known as ringed sideroblastic anemia cells.
The cause of neutropenia is still unclear; however, the arrest of maturing myelocytes, or neutrophil precursors, may cause the neutrophil deficiency. [2] [6]
Zinc intoxication may cause anemia by blocking the absorption of copper from the stomach and duodenum. [3] Zinc also upregulates the expression of chelator metallothionein in enterocytes, which are the majority of cells in the intestinal epithelium. [3] Since copper has a higher affinity for metallothionein than zinc, the copper will remain bound inside the enterocyte, which will be later eliminated through the lumen. [3] This mechanism is exploited therapeutically to achieve negative balance in Wilson's disease, which involves an excess of copper. [3] But in copper-deficient individuals, zinc excess may cause this mechanism to further deplete copper levels.
The diagnosis of copper deficiency may be supported by a person's report of compatible signs and symptoms, findings from a thorough physical examination, and supportive laboratory evidence. Low levels of copper and ceruloplasmin in the serum are consistent with the diagnosis as is a low 24 hour urine copper level. [20] Additional supportive bloodwork findings also include neutropenia and anemia. [20] MRI imaging may demonstrate increased T2 signal of the dorsal column–medial lemniscus pathways. [20]
Copper deficiency is a very rare disease and is often misdiagnosed several times by physicians before concluding the deficiency of copper through differential diagnosis (copper serum test and bone marrow biopsy are usually conclusive in diagnosing copper deficiency). On average, patients are diagnosed with copper deficiency around 1.1 years after their first symptoms are reported to a physician. [3] Copper deficiency can be treated with either oral copper supplementation or intravenous copper. [7] If zinc intoxication is present, discontinuation of zinc may be sufficient to restore copper levels back to normal, but this usually is a very slow process. [7] People with zinc intoxication will usually have to take copper supplements in addition to ceasing zinc consumption. Hematological manifestations are often quickly restored back to normal. [7] The progression of the neurological symptoms will be stopped and sometimes improved with appropriate treatment, but residual neurological disability is common. [20]
Foix–Alajouanine syndrome, also called subacute ascending necrotizing myelitis, is a disease caused by an arteriovenous malformation of the spinal cord. In particular, most cases involve dural arteriovenous malformations that present in the lower thoracic or lumbar spinal cord. The condition is named after Charles Foix and Théophile Alajouanine who first described the condition in 1926.
Wilson's disease is a genetic disorder characterized by the excess build-up of copper in the body. Symptoms are typically related to the brain and liver. Liver-related symptoms include vomiting, weakness, fluid build-up in the abdomen, swelling of the legs, yellowish skin, and itchiness. Brain-related symptoms include tremors, muscle stiffness, trouble in speaking, personality changes, anxiety, and psychosis.
Anemia or anaemia is a blood disorder in which the blood has a reduced ability to carry oxygen. This can be due to a lower than normal number of red blood cells, a reduction in the amount of hemoglobin available for oxygen transport, or abnormalities in hemoglobin that impair its function.
Occipital horn syndrome (OHS), formerly considered a variant of Ehlers–Danlos syndrome, is an X-linked recessive mitochondrial and connective tissue disorder. It is caused by a deficiency in the transport of the essential mineral copper, associated with mutations in the ATP7A gene.
Pernicious anemia is a disease where not enough red blood cells are produced due to a deficiency of vitamin B12. Those affected often have a gradual onset. The most common initial symptoms are feeling tired and weak. Other symptoms may include shortness of breath, feeling faint, a smooth red tongue, pale skin, chest pain, nausea and vomiting, loss of appetite, heartburn, numbness in the hands and feet, difficulty walking, memory loss, muscle weakness, poor reflexes, blurred vision, clumsiness, depression, and confusion. Without treatment, some of these problems may become permanent.
Leigh syndrome is an inherited neurometabolic disorder that affects the central nervous system. It is named after Archibald Denis Leigh, a British neuropsychiatrist who first described the condition in 1951. Normal levels of thiamine, thiamine monophosphate, and thiamine diphosphate are commonly found, but there is a reduced or absent level of thiamine triphosphate. This is thought to be caused by a blockage in the enzyme thiamine-diphosphate kinase, and therefore treatment in some patients would be to take thiamine triphosphate daily. While the majority of patients typically exhibit symptoms between the ages of 3 and 12 months, instances of adult onset have also been documented.
Ceruloplasmin is a ferroxidase enzyme that in humans is encoded by the CP gene.
Menkes disease (MNK), also known as Menkes syndrome, is an X-linked recessive disorder caused by mutations in genes coding for the copper-transport protein ATP7A, leading to copper deficiency. Characteristic findings include kinky hair, growth failure, and nervous system deterioration. Like all X-linked recessive conditions, Menkes disease is more common in males than in females. The disorder was first described by John Hans Menkes in 1962.
In neurology, Lhermitte phenomenon, also called the barber chair phenomenon, is an uncomfortable "electrical" sensation that runs down the back and into the limbs. The sensation can feel like it goes up or down the spine. It is painful for some, although others might simply feel strange sensations.
Sideroblastic anemia, or sideroachrestic anemia, is a form of anemia in which the bone marrow produces ringed sideroblasts rather than healthy red blood cells (erythrocytes). In sideroblastic anemia, the body has iron available but cannot incorporate it into hemoglobin, which red blood cells need in order to transport oxygen efficiently. The disorder may be caused either by a genetic disorder or indirectly as part of myelodysplastic syndrome, which can develop into hematological malignancies.
Tropical spastic paraparesis (TSP), is a medical condition that causes weakness, muscle spasms, and sensory disturbance by human T-lymphotropic virus resulting in paraparesis, weakness of the legs. As the name suggests, it is most common in tropical regions, including the Caribbean. Blood transfusion products are screened for human T-lymphotropic virus 1 (HTLV-1) antibodies, as a preventive measure.
Aceruloplasminemia is a rare autosomal recessive disorder in which the liver can not synthesize the protein ceruloplasmin properly, which is needed to transport copper around the blood. Copper deficiency in the brain results in neurological problems that generally appear in adulthood and worsen over time.
Subacute combined degeneration of spinal cord, also known as myelosis funiculus, or funicular myelosis, also Lichtheim's disease, and Putnam-Dana syndrome, refers to degeneration of the posterior and lateral columns of the spinal cord as a result of vitamin B12 deficiency (most common). It may also occur similarly as result of vitamin E deficiency, and copper deficiency. It is usually associated with pernicious anemia.
Mitochondrial neurogastrointestinal encephalopathy syndrome (MNGIE) is a rare autosomal recessive mitochondrial disease. It has been previously referred to as polyneuropathy, ophthalmoplegia, leukoencephalopathy, and intestinal pseudoobstruction. The disease presents in childhood, but often goes unnoticed for decades. Unlike typical mitochondrial diseases caused by mitochondrial DNA (mtDNA) mutations, MNGIE is caused by mutations in the TYMP gene, which encodes the enzyme thymidine phosphorylase. Mutations in this gene result in impaired mitochondrial function, leading to intestinal symptoms as well as neuro-ophthalmologic abnormalities. A secondary form of MNGIE, called MNGIE without leukoencephalopathy, can be caused by mutations in the POLG gene.
Vitamin B12 deficiency, also known as cobalamin deficiency, is the medical condition in which the blood and tissue have a lower than normal level of vitamin B12. Symptoms can vary from none to severe. Mild deficiency may have few or absent symptoms. In moderate deficiency, feeling tired, headaches, soreness of the tongue, mouth ulcers, breathlessness, feeling faint, rapid heartbeat, low blood pressure, pallor, hair loss, decreased ability to think and severe joint pain and the beginning of neurological symptoms, including abnormal sensations such as pins and needles, numbness and tinnitus may occur. Severe deficiency may include symptoms of reduced heart function as well as more severe neurological symptoms, including changes in reflexes, poor muscle function, memory problems, blurred vision, irritability, ataxia, decreased smell and taste, decreased level of consciousness, depression, anxiety, guilt and psychosis. If left untreated, some of these changes can become permanent. Temporary infertility, reversible with treatment, may occur. A late finding type of anemia known as megaloblastic anemia is often but not always present. In exclusively breastfed infants of vegan mothers, undetected and untreated deficiency can lead to poor growth, poor development, and difficulties with movement.
Surfeit locus protein 1 (SURF1) is a protein that in humans is encoded by the SURF1 gene. The protein encoded by SURF1 is a component of the mitochondrial translation regulation assembly intermediate of cytochrome c oxidase complex, which is involved in the regulation of cytochrome c oxidase assembly. Defects in this gene are a cause of Leigh syndrome, a severe neurological disorder that is commonly associated with systemic cytochrome c oxidase deficiency, and Charcot-Marie-Tooth disease 4K (CMT4K).
Anemia is a deficiency in the size or number of red blood cells or in the amount of hemoglobin they contain. This deficiency limits the exchange of O2 and CO2 between the blood and the tissue cells. Globally, young children, women, and older adults are at the highest risk of developing anemia. Anemia can be classified based on different parameters, and one classification depends on whether it is related to nutrition or not so there are two types: nutritional anemia and non-nutritional anemia. Nutritional anemia refers to anemia that can be directly attributed to nutritional disorders or deficiencies. Examples include Iron deficiency anemia and pernicious anemia. It is often discussed in a pediatric context.
Nutritional neuroscience is the scientific discipline that studies the effects various components of the diet such as minerals, vitamins, protein, carbohydrates, fats, dietary supplements, synthetic hormones, and food additives have on neurochemistry, neurobiology, behavior, and cognition.
Copper is an essential trace element that is vital to the health of all living things. In humans, copper is essential to the proper functioning of organs and metabolic processes. Also, in humans, copper helps maintain the nervous system, immune system, brain development, and activates genes, as well as assisting in the production of connective tissues, blood vessels, and energy. The human body has complex homeostatic mechanisms which attempt to ensure a constant supply of available copper, while eliminating excess copper whenever this occurs. However, like all essential elements and nutrients, too much or too little nutritional ingestion of copper can result in a corresponding condition of copper excess or deficiency in the body, each of which has its own unique set of adverse health effects.
Metals in medicine are used in organic systems for diagnostic and treatment purposes. Inorganic elements are also essential for organic life as cofactors in enzymes called metalloproteins. When metals are under or over-abundant in the body, equilibrium must be returned to its natural state via interventional and natural methods.