Objective: Spinal muscular atrophy (SMA) is an autosomal recessive neuromuscular disease characterized by proximal muscle weakness and atrophy. We explored the correlation between disease severity and serum creatinine (Crn) levels in SMA patients during up to 2 years of nusinersen treatment.
Methods: We measured serum Crn in a cohort of 28 SMA patients and 28 gender- and age-matched healthy controls (HCs). After adjusting for age, sex, and BMI, we investigated the association between Crn and disease severity using partial rank correlation and linear mixed models. The predictive performance of Crn was analyzed using linear models.
Results: Compared to HCs, SMA patients had significantly lower Crn values (67.4 ± 14 vs. 23.7 ± 14.8 µmol/L, p < 0.0001). After adjusting for age, sex, and BMI, Crn was positively correlated with HFMSE (p < 0.0001, r = 0.884), MRC (p < 0.0001, r = 0.827), FVC (p = 0.002, r = 0.730), and ulnar nerve CMAP (p < 0.0001, r = 0.807). The Crn levels in patients with ≥4 SMN2 copies were nearly twice those in patients with <4 SMN2 copies (34.1 ± 3.75 vs. 17.2 ± 2.52 µmol/L, p = 0.00145). Ambulatory patients had Crn levels more than twice those of non-ambulatory patients (32 ± 2.33 vs. 12.9 ± 2.38 µmol/L, p < 0.0001). Crn could predict 83.5% of the functional performance variance, which was significantly higher than traditional biomarkers. Conclusion: Crn may reflect disease severity in adolescent and adult SMA and is a potential biomarker for SMA.