Alterations of serum and urinary carnitine profiles in cancer patients: hypothesis of possible significance.

The present study examined the serum and urinary carnitine concentrations of 21 cancer patients with metastatic disease and 13 healthy age-matched controls by taking three consecutive samples during an 8-week period. The serum concentrations of all fractions of carnitine were significantly lower in the female cancer patients than in the female controls. The concentrations of urinary carnitine fractions were relatively higher in the total cancer population; however, only acid-insoluble acylcarnitine (AIAC) was statistically significant. The renal clearance of acid-soluble acylcarnitine (ASAC) and AIAC was significantly greater in cancer subjects than in controls. Significant inverse relationships were established between the ASAC and AIAC clearances and their respective serum concentrations. The renal tubular reabsorption of AIAC was significantly less in cancer patients than in control subjects as indicated by the fractional excretion of carnitine. The increased clearance of acylcarnitine and excretion of large amounts of AIAC are proposed to be a response to chemotherapy and represent a loss of energy to the cancer patient.