Relationship between anti-acetylcholine receptor antibody titres and severity of myasthenia gravis

Objective: To study the relationship of anti acetylycholine receptor antibody (AchR-Ab) titres with the demographic profile and severity of myasthenia gravis (MG). Methods: This prospective study was carried out on inpatients and outpatients at the department of Neurology at Pakistan Institute of Medical Sciences, Islamabad. Seropositive cases of myasthenia gravis were collected and were classified as having low AchR-Ab titres (<50nmol/L) and high AchR-Ab titres (>50nmol/L). The comparison of these patients was done using the following parameters: sex, age, clinical presentations, severity of the disease, repeated nerve stimulation test, prostigmine test, the association with thymus status, other autoimmune diseases, and therapeutic outcome. Results: Out of a total 71 seropositive MG patients enrolled in the study, forty one (57.7%) patients had low titres and thirty (42.2%) had high titres. Their mean age was 33.18±12.99 years (range 13-70) and thirty eight of them were females. The AchR-Ab titers were higher in the younger age group and in women than in men, however, the results were statistically insignificant. The most common presenting symptoms were ocular (91%), followed by generalized weakness with easy fatiguability (57%) and bulbar weakness (46.4%). Majority of the patients at the time of presentation were in Osserman's stage III (43%); while 26% and 19.7% were in stage IIA and IIB respectively. There was no association between the AchR-Ab titers and clinical grades of Osserman's classification. Conclusion: Serum concentration of anti acetylcholine receptor antibodies do not relate with the clinical severity of myasthenia gravis.