The effect of steroid treatment and thymectomy on bone age and height development in juvenile myasthenia gravis

Juvenile myasthenia gravis (JMG) is usually associated with growth retardation; however, no data have been published to date in this regard. The goal of this study was to analyze the developmental status of bone age (BA) and height in JMG patients and to subsequently identify the clinical factors, particularly thymectomy, associated with it to guide clinical practice. We conducted a cross-sectional study of 76 JMG patients to examine whether they had abnormalities of height and bone development according to the distribution of the height standard deviation score (Ht SDS) and BA. Correlation analysis and linear regression analysis were conducted to explore the related factors that may affect bone and height development. The mean BA was delayed 0.13 ± 1.42 years compared with the patients' chronological age (CA). The Ht SDS was also lower than the healthy peers. In multivariate analysis, the age at onset was negatively associated with delayed BA (R (2) = 0.08, p = 0.019), whereas the cumulative intake of prednisone was negatively associated with Ht CASDS (Ht SDS based on CA) (R (2) = 0.168, p = 0.003). There was no significant association between thymectomy and delayed BA and Ht CASDS. Delayed BA and growth retardation existed in JMG patients. The age at onset of JMG was a correlating factor for delayed BA and the cumulative prednisone use may be a determinant of height retardation. Thymectomy had no impact on the growth of bone and height. Monitoring BA and height should become routine care in JMG patients to take appropriate therapeutic interventions.