This study is intended to be a multicenter, prospective, non-randomized, controlled real-world study. Patients receiving L-carnitine injection were included in the experimental group and the control group according to whether they received L-carnitine injection. Patients receiving L-carnitine injection were included in the experimental group, and those receiving L-carnitine injection were included in the control group.To observe the effects of L-carnitine on cardiac function in hemodialysis patients.

Inclusion Criteria:

• Maintenance hemodialysis patients;
• 18 years<80 years;
• Have clear consciousness and independent behavior ability;
• Before dialysis, the total carnitine concentration was less than 40 umol/L, or the free carnitine concentration was less than 35 umol/L.

Exclusion Criteria:

• Acute cardiovascular and cerebrovascular diseases occurred within 1 month;
• Infectious diseases occurred within 1 month; Treatment with glucocorticoid or immunosuppressant;
• Patients who have used L-carnitine within 2 weeks.
• Hematological system tumor or tumor;