Fatigue, physical performance, and carnitine levels in children and adolescents receiving chemotherapy.

Abstract

Fatigue in childhood cancer is a pervasive and distressing symptom that has a physical component described as a "lack of energy". Fatigue, physical performance, and a micronutrient, carnitine, all relate to physical energy and may be influenced by chemotherapy. The purpose of this pilot study is to examine the relationship between the physical performance and carnitine plasma levels and fatigue in child and adolescent cohorts receiving chemotherapy. The study included 30 patients, ages 6 to 17, who were newly diagnosed with cancer and receiving chemotherapy. There were 20 males and 10 females; the child cohort had 16 subjects ages 6 to12. The 14 subjects in the adolescent cohort were ages 13 to 17. Standardized instruments were administered in the 1st and 3rd cycle of chemotherapy between day 15 and 29. Instruments included physical performance tests (Timed Up and Down Stairs [TUDS] and 6-Minute Walk test [6MWT]), carnitine plasma levels, and self-reported Childhood Fatigue Scale or Fatigue Scale for Adolescents. In the child cohort, physical performance measures appeared to improve (TUDS, p = 0.09 and 6MWT, p = 0.09) and free carnitine plasma levels decreased (p = 0.01) between cycles 1 and 3. Fatigue scores also tended to improve (p = 0.05). In the adolescent cohort, there was a suggestion that fatigue decreased (p = 0.15) but other variables evidenced little change. Spearman's rank-order correlation was used to examine relationships between the change in variables from cycle 1 to 3. In 6 to 12 year olds, when time on the TUDS decreased, fatigue tended to decrease (p = 0.11), and when 6MWT distance increased, fatigue decreased (p=0.01). In 13 to 17 year olds, correlations between changes in the physical performance variables and fatigue were slight and not significant. Fatigue may decrease early in treatment as disease symptoms resolve. Fatigue in the 6-12 age group was related to physical performance, which is consistent with previous studies that define fatigue in children as primarily a physical sensation. Adolescent fatigue was not related to physical performance which supports the concept that, in adolescents, fatigue is more complex and includes mental and emotional components.