Copper and Ceruloplasmin: When to Test for Copper Deficiency or Excess

The basic tests are measurement of total serum copper and of ceruloplasmin — a protein made in the liver that binds most of the copper circulating in the blood and has a copper-dependent oxidase activity. These are complemented by 24-hour urinary copper (urine collected over 24 hours, in a copper-free container) and, in specialist centres, exchangeable copper and the copper content of liver tissue. The Wilson disease guidelines (EASL-ERN 2025) list as components of diagnosis: the clinical picture, plasma ceruloplasmin, 24-hour urinary copper excretion, liver copper content and molecular analysis of the ATP7B gene, and for diagnosis they recommend the Leipzig score and, additionally, determination of relative exchangeable copper.

For the reader the conclusion is practical: a single copper or ceruloplasmin value 'outside the range' is the start of a conversation with the doctor, not a diagnosis. Reference ranges depend on the laboratory, method, sex and age (in pregnant women and those taking oestrogens, copper and ceruloplasmin are physiologically higher). We do not enter specific thresholds for Wilson disease here because they require reference to the full text of the guidelines and assessment by a specialist — you will find them in the published EASL recommendations.

Copper deficiency is regarded as rare but probably under-diagnosed. The best-documented causes are gastrointestinal surgery and excess zinc. In a retrospective review from the Mayo Clinic covering 40 patients with copper deficiency and haematological abnormalities, 25% had undergone bariatric surgery and a further 35% other gastrointestinal surgery, most often gastric resection; in 12 people no cause was established. Other causes are malabsorption syndromes (for example coeliac disease, inflammatory bowel disease), long-term parenteral nutrition without copper supplementation, and also excessive zinc intake, which induces copper-binding metallothionein in enterocytes and blocks copper absorption.

What follows from this? People after bariatric operations (especially procedures involving bypass of the intestine) are genuinely at risk of copper deficiency even several years later — not only in the first months. That is why the postoperative plan usually includes periodic micronutrient checks, and with new symptoms (fatigue, anaemia, gait disturbance) copper and ceruloplasmin testing should be part of the work-up — alongside vitamin B12, which we write about in separate articles. The reliability of frequency estimates is limited by differences in definitions and populations, so treat the percentages given as an order of magnitude.

Two conclusions have practical significance. First, changes in the blood (anaemia, neutropenia, thrombocytopenia) are often the first signal and are reversible after copper is replaced, whereas neurological damage is often permanent or only partly reversible — hence the importance of early diagnosis. Second, the marrow and blood picture can resemble a myelodysplastic syndrome: in the Mayo Clinic review (Halfdanarson 2008) vacuolisation of myeloid precursors and ring sideroblasts were described, and the authors called copper deficiency an uncommon but very treatable cause of haematological abnormalities. In a large part of the reports myelopathy and neuropathy are added, with symptoms resembling vitamin B12 deficiency (impaired deep sensation and gait).

Wilson disease is an inherited, autosomal recessive disorder of copper metabolism caused by mutations in the ATP7B gene — it leads to accumulation of copper in the liver, brain and other organs. As the review in Nature Reviews Disease Primers (Członkowska et al., 2018) summarises, the course is highly variable, but progressive liver disease is common, and neurological and psychiatric disorders may occur. The disease is potentially treatable: treatment involves chelators (penicillamine, trientine) and zinc salts, and early diagnosis is key. Diagnosis is based on algorithms combining symptoms, parameters of copper metabolism and DNA analysis.

Low ceruloplasmin is a classic screening indicator, but its accuracy is limited. In a paediatric study from Asan Medical Center (Kim et al., 2015), among 2834 children with hepatitis in whom ceruloplasmin was measured, Wilson disease was diagnosed in 181 (6.4%). At a threshold of <20 mg/dL the sensitivity was 93.4%, specificity 84.2%, and false-positive results made up 14.7% (418 children); false negatives 0.4% (12 children). A lower threshold of ≤16.6 mg/dL improved accuracy (specificity 94.9%, sensitivity 91.2%). This is a retrospective single-centre study in children and cannot be transferred directly to adults, but it shows that a low ceruloplasmin result often does not mean Wilson disease and that 'ordinary' screening needs further work-up.

Who is diagnostic work-up directed at? Usually people with unexplained acute or chronic liver disease, with movement disorders, tremor, dysarthria or newly appeared behavioural changes and psychiatric symptoms in a young person, and also family members of an affected patient. Screening healthy people without symptoms and without a family history has no justification. Taking 'copper-detox' preparations or dietary restrictions on your own on the basis of one borderline result is not recommended — the result requires assessment by a hepatologist or neurologist.

We write about the general principles of preparing for blood tests in our entry on reading test results. For copper, of particular importance are: pregnancy and taking oestrogens (raise copper and ceruloplasmin), acute infection or inflammation (raises ceruloplasmin as an acute-phase protein) and low albumin and malnutrition (lower it). Interpreting a single result in a chronically ill person therefore requires caution and, if possible, a repeat after the acute phase has resolved.

Copper deficiency is treated by replacing copper (orally or intravenously, depending on severity and absorption) and removing the cause — stopping excess zinc, correcting diet or nutrition, treating malabsorption. In the Scottish review, after such management cytopenias resolved in 93% of patients, whereas neurological improvement was achieved in only some; this is an argument for rapid action once symptoms appear, not for 'preventive' copper intake by everyone. The dose and route are set by the doctor on the basis of the result and symptoms.

Wilson disease is treated chronically and under specialist supervision: with copper chelators (penicillamine, trientine) and/or zinc salts, with monitoring of symptoms, liver tests and copper metabolism (urinary excretion, exchangeable copper) to detect treatment that is too weak or too strong. It is worth noting a paradox: zinc salts are one of the drugs used in Wilson disease (they are listed in the abstract of the EASL-ERN guidelines), and the same zinc in excess in a person without this disease can lead to copper deficiency — which is why the zinc dose should always be matched to the indication and supervised.

If you take zinc supplements in doses higher than a few tens of milligrams a day for many months, talk to your doctor about a check-up copper measurement, even if you feel well. According to the BOND review, doses above 50 mg/day reduced the activity of a copper-dependent enzyme, on which the US upper intake limit for zinc, 40 mg/day for adults, was based.

To sum up: the copper and ceruloplasmin test makes sense above all when there is a concrete reason — anaemia or neutropenia with neurological symptoms in a person from a deficiency risk group, or unexplained liver or neurological disease in a young person when Wilson disease is suspected. The result must always be assessed together with the blood count, zinc, liver tests and symptoms, and doubtful or atypical results referred to a specialist. A copper deficiency detected early enough is largely reversible; delayed diagnosis can leave a permanent neurological mark.