Aim To study the relation between mid-upper arm circumference (MUAC) and calf circumference (CC) and the actual weight of children on admission to the paediatric intensive care unit (PICU). To investigate the value of an equation based on data for healthy children to estimate weight from the measured MUAC.

Patients and Methods Data of different databases were used. Children aged >14 days were included. Weight, MUAC and CC were measured at the same day during hospital admission. Malnutrition was defined as an SD score <−2 for any of these anthropometric variables.

Results Data of 298 children (165 male) with a median age of 0.44 years (range 15 days to 17 years) were analysed. The prevalence of malnutrition was 26.4% using weight for age (n  =  148), 20.5% using MUAC (n  =  176) and 32.0% using CC (n  =  178). There was a highly significant correlation between the actual measured weight on admission and both the MUAC (r  =  0.946, p<0.001) and CC (r  =  0.957, p<0.001). Using a formula to calculate weight from the measured MUAC in healthy children, we found that in only 10% of the children was the estimated weight within 10% of the actual measured weight.

Conclusion MUAC and CC can be used to determine nutritional status in children admitted to the PICU. A highly significant correlation was found between actual measured weight and MUAC, but it was not possible to estimate the weight reliably using an equation based on the measured MUAC.