Using AChR antibody titres to predict treatment responses in myasthenia gravis

Detection of a specific antibody in the serum (and cerebrospinal fluid if appropriate) of patients with a range of neurological disorders can trigger consideration of a trial of immunotherapy with the hope of a substantial improvement. A common question, therefore, is ‘how useful is measuring the antibodies during follow-up?’ My answer is usually ‘it can be helpful but only if the antibody levels are calculated carefully, employing serial serum dilutions’. Most commercial and hospital laboratories use single concentrations, designed for sensitivity and specificity, rather than interpretation of treatment responses; even if reported as a titre or in molar terms, the results are seldom suitable for comparisons over time. It was interesting to see, therefore, that Kojima et al 1 were able to predict outcome in 53 AChR-antibody positive myasthenia gravis (MG) patients by testing at first diagnosis and again between 55 and 84 days later. …