Lack of association between serum apelin levels and sarcopenia in elderly malnourished subjects.

Objective: Sarcopenia is a condition characterized by muscle mass loss. Skeletal muscle is capable of producing and secreting different molecules called myokines, and apelin is one of them. The literature contains contradictory data on the relationship between apelin and sarcopenia. We decided to investigate the role of apelin in sarcopenia in subjects with disease-related malnutrition (DRM), a group of patients with a high rate of sarcopenia.

Patients and methods: 83 elderly patients with DRM assessed according to the Global Leadership Initiative on Malnutrition (GLIM) criteria were included in the study, with a mean age of 69.9±3.8 years. Anthropometric data, muscle mass by ultrasound at the rectus femoris quadriceps (RFQ) level, bioimpedance [skeletal muscle mass (SMM), appendicular SMM (aSMM) and aSMM index (aSMMI)], dynamometry, biochemical parameters, dietary intake, circulating apelin levels were determined in all patients.

Results: a total of 33 patients (37.9%) were diagnosed with sarcopenia, while 54 patients did not present sarcopenia (60.1%). Body weight (-5.5±2.0 kg, p=0.01), calf circumference (-1.9±0.2 cm, p=0.02), phase angle (-0.6±0.2º, p=0.01), reactance (-6.8±2.3 Ohms, p=0.03), resistance (-38.8±12.3 Ohms, p=0.04), SMM (-2.2±0.3 kg, p=0.04), aSMM (-2.2±0.2 kg, p=0.03) and aSMMI (-0.6±0.2 kg, p=0.02), dominant muscle area (-0.6±0.2 cm2, p=0.04), dominant Y axis (-0.4±0.1 cm, p=0.03), dominant X/Y axis (1.1±0.3 cm, p=0.04), strength (-5.1±1.3 kg, p=0.01), albumin (-0.9±0.1 g/dl, p=0.02) and prealbumin (-4.6±0.7 mg/dl, p=0.02) were worse in patients with sarcopenia than non-sarcopenic patients. Circulating apelin levels were similar in both groups. No significant correlation of apelin levels was detected, either with bioimpedance data or with muscle ultrasonography data. The multivariant analysis did not detect a significant association of apelin with the presence of sarcopenia.

Conclusions: Our study shows a lack of association between apelin and sarcopenia in elderly malnourished patients.