A Study To Correlate Serum Creatine Kinase Level With Motor Function In Children With Duchenne Muscular Dystrophy

Abstract

Background: Duchenne muscular dystrophy (DMD) is a severe X‑linked recessive neuromuscular disorder of childhood characterized by progressive proximal muscle weakness and markedly elevated serum creatine kinase (CK) levels, but the relationship between CK and motor function across different severity levels remains uncertain. The objective of this study was to correlate serum creatine kinase levels with motor function in children with Duchenne muscular dystrophy using Manual Muscle Testing (MMT) grades and functional scales.

Methodology: This hospital-based observational and analytical study was conducted in the Department of Paediatrics, Mahatma Gandhi Medical College and Hospital, Jaipur, and included 50 genetically confirmed DMD patients aged 3–18 years. Demographic data, clinical features, MMT grades of neck flexors, shoulder abductors and knee extensors, Brooke and Vignos functional scales and serum CK levels were recorded and analyzed using descriptive statistics, Kruskal-Wallis test with Bonferroni-adjusted Mann-Whitney U test and Spearman and Pearson correlation coefficients.

Results: The majority of participants belonged to the 5-10 years age group (54%), followed by 11-15 years (38%), indicating most commonly observed in middle childhood. The mean age was 9.68 ± 3.285 years with a median of 9 years. Children with lower average MMT scores (<2.0) had markedly elevated CK levels (mean 36,314.31 ± 26,157.72 U/L; median 37,832 U/L), whereas those with moderate (2.0–3.0) and higher (>3.0) MMT scores showed progressively lower CK values (means 9,459.82 ± 3,923.94 U/L and 5,030.06 ± 4,693.34 U/L, respectively), and these differences were statistically significant (Kruskal-Wallis H = 17.299, p = 0.0001, with all Bonferroni-adjusted pairwise comparisons p < 0.05). Serum CK demonstrated a strong, highly significant negative correlation with average MMT score (Spearman ρ = −0.633, p < 0.001), and similar inverse correlations were observed for neck flexors, shoulder abductors and knee extensors individually, confirming that higher CK levels consistently corresponded to poorer motor function across the examined muscle groups.

Conclusion: Higher serum creatine kinase levels are associated with poorer motor function in children with Duchenne muscular dystrophy, indicating that CK can serve as a useful biochemical marker that complements clinical motor assessments in evaluating disease severity.