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Oxford University Hospitals NHS Foundation Trust
Immunology

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Potassium Channel Antibodies

Also known as: Voltage gated K+ antibodies NM; Voltage gated K+ channel complex antibodies

Potassium channel antbodies are found in patients with acquired neuromyotonia (40-50%), Morvan's syndrome, limbic encephalitis (paraneoplastic and idiopathic), as well as patients with facio-brachial dystonic seizures (FBDS). Both Morvan's and Limbic Enceophalitis can be associated with thymoma or small cell lung carcinoma (SCLC).

VGKC antibodies have recently been renamed VGKC-complex antibodies, as it is now recognised that the VGKCs are tightly complexed with other proteins and that the radioimmunoprecipitaion assay recognises the complexed proteins as well as the VGKCs themselves. The most common complex proteins discovered so far are LGI1 and CASPR2. However, as not all the complex proteins have been identified, we recommend testing for VGKC-complex antibodies as a first step.

Explanation of equivocal results

Specimen requirements

A 1ml serum sample, although plasma and CSF are acceptable

Cost

40 UKP - UK NHS, International and Private

Laboratory turnaround time

14 days

Laboratory method

Radioimmunoassay (RIA)

Reference range/units

  • units = Pico Moles per Litre
  • 0-69 pML-1 = Negative
  • 70-130 pML-1 = Equivocal
  • >130 pML-1 = Positive

Equivocal results

The equivocal zone of an assay describes a range of values for which the assay concerned does not produce data of sufficient statistical power to provide clinically useful data. Typically these values fall at the top of the negative range and the bottom of the positive range. In these cases the statistical power of the assay is inadequate to differentiate disease from control and therefore the result of the assay is unhelpful in differential diagnosis and clinical management. Please rely on the clinical picture to inform patient diagnosis and management.

Associated tests

Not applicable

Shipping and storage

UK and Ireland

Ambient temperature and first class post. Hays DX users please enquire via email below.

International

Ambient temperature if courier will deliver within 72 hours otherwise consider refrigerated transport. Freezing is not a requirement.

Ensure delivery Monday to Friday 07:00 - 17:30.

Further information and contact details

For further information, email immunology.office@nhs.net