Unit Converter
Copper (Cu)
(Essential Trace Element – Key for Enzyme Function, Iron Metabolism & Wilson Disease Evaluation)
Synonyms
- Copper
- Serum copper
- Plasma copper
- Total copper
- Circulating copper
- Cu²⁺ (biochemical form)
Units of Measurement
- µmol/L
- µg/mL
- µg/dL
- µg/100 mL
- µg%
- µg/L
- mg/L
1 µg/dL = 1 µg/100 mL = 1 µg%
1 µg/mL = 1000 µg/L
Description
Copper is an essential trace metal required for:
- Iron metabolism (via ceruloplasmin)
- Mitochondrial energy production
- Antioxidant defense (superoxide dismutase)
- Neurotransmitter synthesis
- Collagen formation
- Melanin production
About 90–95% of circulating copper is bound to ceruloplasmin, while the rest is loosely bound to albumin or exists as “free copper.”
Clinically, copper measurement is vital in diagnosing:
- Wilson disease
- Copper deficiency
- Copper overload disorders
- Nutritional & malabsorption conditions
Physiological Role
Copper is required for several key enzymes:
- Cytochrome c oxidase (energy metabolism)
- Dopamine β-hydroxylase (neurotransmission)
- Superoxide dismutase (antioxidant)
- Lysyl oxidase (collagen cross-linking)
- Tyrosinase (pigmentation)
Absorption occurs in the small intestine; excess copper is excreted via bile.
Clinical Significance
Low Copper (Hypocupremia)
1. Wilson Disease (Most Important Cause)
- ATP7B mutation → failure to incorporate copper into ceruloplasmin
- Leads to:
- Low serum copper
- Low ceruloplasmin
- High urine copper
- Hepatic copper overload
- Kayser–Fleischer rings
- Low serum copper
2. Malnutrition / Malabsorption
- Celiac disease
- Bariatric surgery
- Chronic diarrhea
- Severe undernutrition
3. Excess Zinc Intake
Zinc induces metallothionein → traps copper → severe deficiency.
4. Nephrotic Syndrome
Loss of ceruloplasmin-bound copper.
5. Menkes Disease (Genetic)
X-linked defect → impaired copper absorption.
Symptoms of Copper Deficiency
- Anemia (microcytic or normocytic)
- Neutropenia
- Myelopathy (resembles B12 deficiency)
- Ataxia
- Peripheral neuropathy
High Copper (Hypercupremia)
Causes:
- Cholestatic liver disease (decreased excretion)
- Acute or chronic liver injury
- Inflammation (ceruloplasmin is acute-phase protein)
- Pregnancy / Oral contraceptives
- Copper poisoning
- Environmental exposure (pipes, industrial)
Symptoms of Copper Toxicity:
- GI pain, nausea
- Hemolysis
- Hepatic failure
- Cardiovascular collapse (in acute massive exposures)
Reference Intervals
(Tietz 8E + AASLD + Mayo + ARUP)
Serum/Plasma Copper
- Men: 70–140 µg/dL (11–22 µmol/L)
- Women: 80–155 µg/dL (13–24 µmol/L)
- Children: similar to adults
- Pregnancy: significantly elevated (up to 2× normal)
Wilson Disease
- Serum copper: Low (<70 µg/dL / <11 µmol/L)
- “Free” copper: High
- 24-hour urine copper: >100 µg/day
- Liver biopsy copper: >250 µg/g dry weight
Unit Meanings
| Unit | Meaning |
| µmol/L | micromole per liter |
| µg/mL | microgram per milliliter |
| µg/dL | microgram per deciliter |
| µg/100 mL = µg% | identical to µg/dL |
| µg/L | microgram per liter |
| mg/L | milligram per liter |
Diagnostic Uses
1. Wilson Disease Diagnosis
Copper panel includes:
- Total serum copper
- Ceruloplasmin
- Free (non-ceruloplasmin) copper
- 24-h urine copper
- Liver biopsy copper
2. Liver Disease Evaluation
Copper rises in cholestatic disorders.
3. Neurologic Disorders
Copper deficiency can mimic B12 deficiency.
4. Nutritional Assessment
Important in:
- Malabsorption
- TPN monitoring
- Bariatric surgery follow-up
5. Toxicology
Evaluate copper overdose or environmental exposure.
Analytical Notes
- Serum or plasma acceptable
- Avoid hemolysis (RBCs contain copper)
- Ceruloplasmin must be measured alongside copper
- Copper is influenced by:
- Pregnancy
- Inflammation
- Estrogen therapy
- Pregnancy
Clinical Pearls
- Low serum copper + low ceruloplasmin = Wilson disease until proven otherwise.
- Always interpret copper with ceruloplasmin, as 90% of circulating copper is bound to it.
- High copper in pregnancy or on oral contraceptives is physiologic, not pathological.
- Copper deficiency causes neuro symptoms identical to B12 deficiency-check both.
- Zinc supplements can cause severe hypocupremia.
Interesting Fact
Wilson disease may present only with psychiatric symptoms (depression, personality change) long before liver or neurologic signs appear—making copper testing lifesaving.
References
- Tietz Clinical Chemistry & Molecular Diagnostics, 8th Edition - Trace Elements.
- AASLD Wilson Disease Guidelines.
- IFCC Metals & Trace Elements Methods.
- Mayo Clinic Laboratories - Copper.
- ARUP Consult - Wilson Disease.
- MedlinePlus / NIH - Copper Test.