Decrease of serum carnitine levels in patients with or without gastrointestinal cancer cachexia.
AIM: To evaluate the levels of serum carnitine in patients with cancer in digestive organs and to compare them with other cancers in order to provide new insights into the mechanisms of cachexia. METHODS: Fifty-five cachectic patients with or without gastrointestinal cancer were enrolled in the present study. They underwent routine laboratory investigations, including examination of the levels of various forms of carnitine present in serum (i.e., long-chain acylcarnitine, short-chain acylcarnitine, free carnitine, and total carnitine). These values were compared with those found in 60 cancer patients in good nutritional status as well as with those of 30 healthy control subjects. RESULTS: When the cachectic patients with gastro-intestinal cancer were compared with the cachectic patients without gastrointestinal cancer, the difference was -6.8 micromol/L in free carnitine (P < 0.005), 0.04 micromol/L in long chain acylcarnitine (P < 0.05), 8.7 micromol/L in total carnitine (P < 0.001). In the cachectic patients with or without gastrointestinal cancer, the difference was 12.2 micromol/L in free carnitine (P < 0.001), 4.60 micromol/L in short chain acylcarnitine (P < 0.001), and 0.60 micromol /L in long-chain acylcarnitine (P < 0.005) and 17.4 micromol/L in total carnitine (P < 0.001). In the cachectic patients with gastrointestinal cancer and the healthy control subjects, the difference was 15.5 micromol/L in free carnitine (P < 0.001), 5.2 micromol /L in short-chain acylcarnitine (P < 0.001), 1.0 micromol/L in long chain acylcarnitine (P < 0.001), and 21.8 micromol/L in total carnitine (P < 0.001). CONCLUSION: Low serum levels of carnitine in terminal neoplastic patients are decreased greatly due to the decreased dietary intake and impaired endogenous synthesis of this substance. These low serum carnitine levels also contribute to the progression of cachexia in cancer patients.