Nutritional status of children with cystic fibrosis measured by total body potassium as a marker of body cell mass: lack of sensitivity of anthropometric measures.
OBJECTIVE
To investigate measures aimed at defining the nutritional status of cystic fibrosis (CF) populations, this study compared standard anthropometric measurements and total body potassium (TBK) as indicators of malnutrition.


METHODS
Height, weight, and TBK measurements of 226 children with CF from Royal Children's Hospital, Brisbane, Australia, were analyzed. Z scores for height for age, weight for age, and weight for height were analyzed by means of the National Centre for Health Statistics reference. TBK was measured by means of whole body counting and compared with predicted TBK for age. Two criteria were evaluated with respect to malnutrition: (1) a z score < -2.0 and (2) a TBK for age <80% of predicted.


RESULTS
Males and females with CF had lower mean height-for-age and weight-for-age z scores than the National Centre for Health Statistics reference (P <.01), but mean weight-for-height z score was not significantly different. There were no significant gender differences. According to anthropometry, only 7.5% of this population were underweight and 7.6% were stunted. However, with TBK as an indicator of nutritional status, 29.9% of males and 22.0% of females were malnourished.


CONCLUSIONS
There are large differences in the percentage of patients with CF identified as malnourished depending on whether anthropometry or body composition data are used as the nutritional indicator. At an individual level, weight-based indicators are not sensitive indicators of suboptimal nutritional status in CF, significantly underestimating the extent of malnutrition. Current recommendations in which anthropometry is used as the indicator of malnutrition in CF should be revised.
McNaughton
S A
SA
Department of Paediatrics and Child Health, University of Queensland, Royal Children's Hospital, Herston, Australia.
Shepherd
R W
RW
Greer
R G
RG
Cleghorn
G J
GJ
Thomas
B J
BJ
D001823:Body Composition; D001827:Body Height; D001835:Body Weight; D002648:Child; D003430:Cross-Sectional Studies; D003550:Cystic Fibrosis / Q000150:complications / Q000378:metabolism / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D009748:Nutrition Disorders / Q000175:diagnosis* / Q000453:epidemiology / Q000209:etiology; D009752:Nutritional Status; D011188:Potassium / Q000378:metabolism*; D012680:Sensitivity and Specificity
D011188:Potassium