This laboratory assay detects IgG autoantibodies against adenylate kinase 5 (AK5), an intracellular enzyme expressed in the central nervous system that plays an important role in cellular energy homeostasis. Anti-AK5 antibodies are specific biomarkers of a rare form of autoimmune limbic encephalitis, typically characterised by subacute amnesia, psychiatric symptoms and, less frequently, seizures. The condition is usually non-paraneoplastic and occurs predominantly in older males. The presence of anti-AK5 antibodies suggests a cytotoxic T-cell–mediated pathogenesis, with neuronal injury and a limited response to conventional immunosuppressive therapies. Clinical workup often shows typical MRI findings (mesial temporal T2/FLAIR hyperintensities) and severe cognitive deficits that may persist despite treatment.
This test supports the differential diagnosis, helping to distinguish anti-AK5 encephalitis from more common autoimmune encephalitis (e.g., anti-LGI1). It is recommended in patients with a rapidly progressive limbic encephalitis phenotype, especially when no neoplasm is found and immunotherapy response is poor. Diagnosis is supported by detection of anti-AK5 in serum and/or cerebrospinal fluid (CSF). As CSF provides higher sensitivity than serum, testing both sample types is recommended.
Serum, plasma, CSF
IFA cells
Fasting for at least 8-12 hours before sampling
Refer to the Health Service Charter to check storage conditions
+2/+8°C
This test provides the quantitative determination of total tau protein to support the diagnosis of Alzheimer’s disease.
This test provides the quantitative determination of tau protein phosphorylated at threonine 181 (pTau181), to support the diagnosis of Alzheimer’s disease.
Test for the determination of human autoantibodies against NMDAR to support the diagnosis of paraneoplastic neurological syndromes with an intermediate-risk phenotype.
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