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Ceruloplasmin
(Copper-Carrying Acute-Phase Protein – Key Marker for Wilson Disease)
Synonyms
- Ceruloplasmin
- Copper oxidase
- Ferroxidase I
- Cp
- Blue copper-binding protein
Units of Measurement
- mmol/L
- µmol/L
- g/L
- mg/dL
- mg/100 mL
- mg%
- mg/mL
Description
Ceruloplasmin is a copper-binding α2-glycoprotein synthesized in the liver.
It carries ~90–95% of circulating copper.
Functions include:
- Transport of copper
- Ferroxidase activity (Fe²⁺ → Fe³⁺) enabling iron loading onto transferrin
- Antioxidant activity
- Acute-phase response protein
Clinically, ceruloplasmin is the primary screening test for Wilson disease, a disorder of copper overload due to ATP7B mutation.
Low ceruloplasmin indicates impaired copper incorporation into apoceruloplasmin → rapid degradation.
Physiological Role
- Transports copper to tissues
- Essential for iron metabolism (ferroxidase)
- Anti-inflammatory activities
- Increases during pregnancy, inflammation, estrogen exposure
Clinical Significance
Low Ceruloplasmin (Most important)
1. Wilson Disease (Primary Diagnostic Use)
- Characteristic low ceruloplasmin: < 0.20 g/L (20 mg/dL)
- Due to failure to incorporate copper into ceruloplasmin
- Leads to:
- Low serum ceruloplasmin
- High urinary copper
- High hepatic copper
- Kayser–Fleischer rings
- Low serum ceruloplasmin
2. Severe Liver Disease
- Cirrhosis
- Fulminant hepatic failure
(reduced synthesis)
3. Menkes Disease
X-linked disorder of copper transport.
4. Malnutrition / Malabsorption
- Protein deficiency
- Nephrotic syndrome (loss of proteins)
5. Aceruloplasminemia
Rare inherited disorder → iron overload, diabetes, neurologic disease.
High Ceruloplasmin
Usually due to increased synthesis.
Causes:
- Acute inflammatory states (acute-phase reactant)
- Pregnancy
- Oral contraceptives / estrogen therapy
- Chronic infections
- Autoimmune diseases
- Malignancy
Reference Intervals
(Tietz 8E + AASLD + Mayo + ARUP)
Adults
- 0.20 – 0.60 g/L
- 20 – 60 mg/dL
Children
- Slightly lower in early infancy; reaches adult levels by 6 months.
Wilson Disease Threshold
- <0.20 g/L (20 mg/dL) → highly suggestive
- <0.10 g/L → strongly indicative
Additional Diagnostic Criteria (Wilson)
- 24-hr urine copper >100 µg/day
- Hepatic copper >250 µg/g dry weight
- ATP7B mutation analysis
Unit Meanings
| Unit | Meaning |
| mmol/L | millimole per liter (rarely used) |
| µmol/L | micromole per liter |
| g/L | grams per liter |
| mg/dL | milligrams per deciliter |
| mg/100 mL = mg% | identical to mg/dL |
| mg/mL | milligrams per milliliter |
Diagnostic Uses
1. Wilson Disease Screening
- First-line test
- Used with:
- Serum copper
- Urine copper
- Liver biopsy copper
- Slit-lamp exam (KF rings)
- Serum copper
2. Evaluation of Low Copper States
- Menkes disease
- Malabsorption
- Protein loss states
3. Monitoring Liver Disorders
- Acute hepatitis
- Cirrhosis
- Pediatric liver disease
4. Inflammation Marker
Mildly increases during inflammation.
5. Iron Metabolism Disorders
Low ceruloplasmin in aceruloplasminemia → iron accumulation.
Analytical Notes
- Serum preferred; plasma acceptable
- Avoid hemolysis (minor effect)
- Ceruloplasmin is an acute-phase reactant → always interpret with clinical context
- Estrogen therapy increases levels
- Immunoturbidimetry or nephelometry used in most labs
Clinical Pearls
- Low ceruloplasmin does NOT always mean Wilson disease-confirm with urine copper.
- In fulminant Wilson disease, serum copper may be high, but ceruloplasmin is low.
- Pregnancy and OCPs increase ceruloplasmin significantly.
- Ceruloplasmin may be normal in hepatic-predominant Wilson disease.
- Always check serum copper + urine copper alongside ceruloplasmin.
Interesting Fact
Ceruloplasmin is a blue-colored protein due to its eight bound copper ions - one of the few naturally blue human proteins.
References
- Tietz Clinical Chemistry & Molecular Diagnostics, 8th Edition - Copper & Ceruloplasmin.
- AASLD Wilson Disease Practice Guidelines.
- EFNS Guidelines - Wilson and Copper Metabolism Disorders.
- Mayo Clinic Laboratories - Ceruloplasmin.
- ARUP Consult - Wilson Disease.
- IFCC Reference Methods - Ceruloplasmin & Copper.