Background <p>Lumbar disc herniation (LDH) accompanied by muscle paresis causes functional limitations. There is no biomarker for motor deficit in LDH. The association between serum creatine kinase (CK) and muscle paresis has not been well defined.</p> Objectives <p>This study aims to compare serum CK levels in LDH patients with and without motor deficits, and to correlate CK levels with clinical characteristics (age, BMI, symptom duration, affected myotome, motor deficit grade) to assess the potential of CK as a biomarker.</p> Methods <p>This study represents a single-institution retrospective analysis of a prospective observational cohort. Admission, baseline, and delta (Δ) CK levels were compared between patients with and without motor deficits and across symptom duration using ANOVA. To examine the relationship between CK and clinical variables (age, BMI, symptom duration, primary myotome, secondary myotome, primary Medical Research Council (MRC), and secondary MRC), a Generalized Additive Model (GAM) was used. Symptom duration was categorized. Motor deficit grade was measured using MRC scale for muscle strength.</p> Results <p>A total of 87 patients (no motor deficits N = 32 [37%], motor deficits (N = 55 [63%]) were included in the study. We observed a trend to elevated CK (<i>p</i> = 0.051) in those with motor deficits. CK elevation was present in 0–3&#xa0;days (ΔCK = 48 U/L) and peaked in those with 4–7&#xa0;days (ΔCK = 317 U/L) of symptoms before reaching baseline level. In the GAM model, the MRC grade (<i>p</i> = 0.022) of the predominantly affected myotome correlated significantly with the CK level at admission. Higher CK levels were found in patients with more than one myotome affected.</p> Conclusion <p>These findings suggest that CK level elevation correlates with the primary MRC grade and by the number of affected myotomes. Further prospective studies are warranted to validate CK’s diagnostic value in this setting.</p>