ANTHROPOMETRIC–PHYSIOLOGICAL DECOUPLING IN SEVERE ACUTE MALNUTRITION: DIFFERENTIAL ASSOCIATIONS OF WEIGHT-FOR-HEIGHT Z-SCORE AND MID-UPPER ARM CIRCUMFERENCE WITH BIOCHEMICAL MARKERS

Abstract

Introduction: Severe acute malnutrition (SAM) induces profound metabolic and endocrine alterations. While weight-for height Z-score (WHZ) and mid-upper arm circumference (MUAC) are standard diagnostic indices for severity assessment, their capacity to accurately reflect underlying physiological status at extreme levels of wasting remains unclear. Objective: This study aimed to evaluate whether WHZ and MUAC differ in their associations with biochemical markers of physiological status in children with SAM, thereby exploring the hypothesis of anthropometric–physiological decoupling. Materials And Methods: A retrospective secondary analysis was conducted on 68 children (aged 6–48 months) with non-edematous SAM. The study analyzed anthropometric measures (WHZ and MUAC) against biochemical markers, including free T3 (FT3), free T4 (FT4), and serum albumin. Associations were assessed using linear regression models, including multivariable adjustments for both anthropometric indices. Additionally, a categorical analysis compared severe (WHZ −3.0 to −5.0) and extreme (WHZ < −5.0) wasting groups. Results: WHZ demonstrated no significant independent association with FT3, FT4, or serum albumin. Conversely, MUAC exhibited a significant positive association with FT3 and albumin, alongside a non-significant trend for FT4. Furthermore, categorical analyses revealed no significant differences in mean FT3, FT4, or albumin levels between the severe and extreme wasting groups. Conclusion: In children with SAM, WHZ failed to associate with biochemical markers of physiological status, whereas MUAC maintained significant predictive value. These findings indicate anthropometric–physiological decoupling at extreme wasting levels, suggesting MUAC serves as a more reliable indicator of physiological reserve than WHZ in severely malnourished pediatric populations.