An exploratory study of serum creatinine levels in patients with amyotrophic lateral sclerosis.

The etiology of amyotrophic lateral sclerosis (ALS) remains unknown, but existing data argue for a role of creatinine in ALS pathophysiology. Our aim is to clarify the correlation between serum creatinine and ALS in Chinese population. A total of 512 sporadic ALS (SALS) patients and 501 age- and gender-matched healthy controls were included. Revised ALS Functional Rating Scale (ALS-FRS-R) was used to assess the motor functional status of SALS patients. Survival analysis was performed using Kaplan-Meier method. Serum creatinine levels were significantly lower in SALS patients than in controls (p < 0.001). Patients with the second, the third and highest quartiles of creatinine levels had a significantly lower presence of ALS compared to those with the lowest quartile (p for trend <0.001). However, decreased presence of ALS was not found in the highest quartiles compared with the lowest quartiles in females. Sporadic ALS patients with different site of onset have similar serum creatinine levels, but underweight patients presented lower levels of serum creatinine. Patients with low serum creatinine levels are more likely to have severe motor impairment and low body mass index (BMI) values. This study demonstrates that SALS patients have lower serum creatinine levels than well-matched controls. Higher levels of serum creatinine are less likely to be associated with the presence of ALS in Chinese populations. Low serum creatinine levels may be related to severe motor impairment in SALS patients, after adjusting the confounding factor-BMI. However, serum creatinine has no deleterious impact on survival in ALS.