Copper-65 Uptake Test Protocol

*** Please note the copper-65 absorption test has been permanently withdrawn due to lack of availability of suitable copper-65 solution. ***

Background

The ⁶⁵Cu uptake test is a useful test in the diagnosis of Wilson’s disease and copper malabsorption. Most copper in the body has an atomic weight of 63 and a smaller percentage exists as ⁶⁵Cu. This is a stable isotope (i.e. non-radioactive) form of copper. The test measures the increase of ⁶⁵Cu / ⁶³Cu in blood samples that are collected after the administration of ⁶⁵Cu. In normal individuals there is an early rise of plasma ⁶⁵Cu / ⁶³Cu after its absorption and then a fall as it is taken up by the liver. This is followed by a rise over the next few days as it is incorporated into caeruloplasmin. In Wilson’s disease the early peak is pronounced and the late rise is suppressed.

Protocol
• Patients on penicillamine or trientine chelation therapy should have this stopped at least 48 hours before the test.
• Patient is fasted for 12 hours before the test.
• Collect a basal blood sample for copper prior to administering the ⁶⁵Cu solution.
• 3 mg of ⁶⁵Cu is administered to adults as a drink. For tests on children (≤ 16 years) the dose is adjusted according to weight measure. Measure 0.04 mL/kg.
• Add the 1 to 3 mL of ⁶⁵Cu solution provided to a glass or plastic cup and make up to a small volume (around 100 mL) in water or a soft drink. This should be taken orally. The solution is unpleasant to taste so ideally it should be consumed in a small number of gulps to minimise the risk of vomiting. An anti-emetic may be given if necessary.
• To investigate suspected Wilson’s Disease, collect blood samples at 1h, 2h and 6h, (accurate to within a few minutes) and at 72h (3 days). To investigate suspected copper malabsorption, include samples at 4h and 8h.
• (Measurement of half life of ⁶⁵Cu to aid in identification of heterozygotes can be done by collection of weekly samples up to eight weeks.)

Notes
• Store ⁶⁵Cu solution in fridge or if test is delayed for more than four days store in freezer.
• Blood samples are collected into lithium heparin or trace element blood tubes. Please liaise with your local Biochemistry Department and ask them to centrifuge blood, separate plasma from cells, and store plasma at 4°C. When all samples have been collected please send to Department of Clinical Biochemistry, Macewen Building, Glasgow Royal Infirmary, Castle Street, GLASGOW, G4 0SF clearly requesting “65Copper Uptake Test” on the request form. Please notify us (STEMDRL@ggc.scot.nhs.uk or by phoning 0141 2429560) approximately when the sample will be sent.
• Fasting can be broken after the 2 hour sample is collected.

Reference ranges for half life
Heterozygous for Wilson’s Disease: t½ = 32 to 77 days. Normals: t½ = 14 to 26.