Pitfalls in the assessment of body composition in survivors of acute lymphoblastic leukaemia

• Published in: Archives of disease in childhood 2004-01, Vol.89 (1), p.64-68
• Main Authors: Warner, J T, Evans, W D, Webb, D K H, Gregory, J W
• Format: Article
• Language: English
• Subjects: Absorptiometry, Photon; acute lymphoblastic leukaemia; Acute lymphocytic leukemia; acute myeloid leukaemia; Adipose Tissue - chemistry; Age; ALL; AML; BIA; bioelectrical impedance; Biological and medical sciences; BMI; Body Composition; Body Mass Index; Body Water - chemistry; Body Weight; Care and treatment; central nervous system; Chemotherapy; Child; Children & youth; CNS; Cohort Studies; Control Groups; DEXA; Diagnosis; dual energy X-ray absorptiometry; Electric Impedance; fat free mass; fat mass; FFM; growth hormone; Hematologic and hematopoietic diseases; Humans; Hydration; hydration constant; Impedance; Leukemia; Leukemias. Malignant lymphomas. Malignant reticulosis. Myelofibrosis; Lymphoma; Medical research; Medical sciences; Medicine, Experimental; NHL; non-Hodgkin’s lymphoma; Obesity; Original; Potassium; Potassium - analysis; Precursor Cell Lymphoblastic Leukemia-Lymphoma - physiopathology; Scientific Concepts; Siblings; Survivors; whole body potassium
• ISSN: 0003-9888; 1468-2044

Background: Body fat mass (FM) and fat free mass (FFM) in childhood are often estimated by conversion of a measured variable into compartmental body composition using constants or regression equations that have been previously derived in healthy individuals. Application of such constants or equations to children with disease states may lead to inappropriate conclusions since the “normal” relationships may become altered. Aims and Methods: To test this hypothesis by taking measurements of body composition using dual energy x ray absorptiometry (DEXA) as a “gold standard” method and calculating hydration and body potassium constants using isotopic water dilution and whole body potassium counting. Measurements of bioelectrical impedance (BIA) by two different analysers (RJL and Holtain) were also performed to allow comparison with body water measurements. Results: Measurements were performed in 35 children treated for acute lymphoblastic leukaemia (ALL) and compared to those in 21 children treated for a variety of other malignancies and 32 healthy sibling controls. The mean hydration and potassium content of FFM was significantly reduced in the ALL group compared to both other malignancies and controls. Application of equations derived from controls for the measurement of FFM derived from bioelectrical impedance led to an underestimation of 1.15 kg when compared to that derived from DEXA in children treated for ALL but not in other malignancies. For all groups combined, BIA was significantly different in the two analysers. Conclusion: Care needs to be taken in the application of equations derived from the normal population to body composition measurement in children treated for ALL.