Practical problems with the use of MUAC

Measurement error - in spite of the convenience and ease of measurement, MUAC measurement requires careful training and supervision in order to prevent wrapping the measuring tape too tightly or too loosely, which results in an erroneous estimate. One study estimated that the smallest change over time detectable in MUAC was 8-10%, when measurements were taken by different observers⁷³. A second study demonstrated that MUAC measurements show more inter-observer variability than weight and height measurements ⁷⁴.

MUAC should be measured at the mid-point of the upper arm between the shoulder (lateral end of the clavicle) and elbow (inferior tip of the olecranon). Although this not critical in young children who often have little muscle contour in the upper arm, it becomes increasingly important in post-pubertal adolescents who have developed adult musculature. Therefore workers will have to be carefully trained to measure adolescent MUACs.