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Mid-arm circumference and mid-arm circumference: head circumference ratio for assessing longitudinal growth in
M K Georgieff1, U M Amarnath, S R Sasanow
1University of Minnesota Hospital, Minneapolis/St. Paul 55455.
Insights
Mid-arm circumference (MAC) and MAC:head circumference ratio (MAC:HC) are useful for assessing longitudinal growth in preterm infants. These measurements help avoid overestimating malnourishment when nutritional intake is adequate.
Area of Science:
- Neonatalogy
- Pediatric Nutrition
- Growth Monitoring
Background:
- Assessing longitudinal growth in hospitalized preterm infants is crucial for optimal outcomes.
- Traditional weight measurements may not accurately reflect nutritional status in this population.
- Mid-arm circumference (MAC) and MAC:head circumference ratio (MAC:HC) offer potential alternative growth assessment tools.
Purpose of the Study:
- To evaluate the usefulness of MAC and MAC:HC in assessing longitudinal growth in hospitalized preterm infants.
- To compare the diagnostic accuracy of MAC and MAC:HC with traditional weight and weight/length for age measurements.
- To determine if MAC and MAC:HC can accurately identify growth faltering during periods of adequate nutrition.
Main Methods:
- Prospective study of 50 preterm, low-birth-weight infants.
- Regular measurements of weight, length, occipitofrontal head circumference (OFC), MAC, and MAC:HC.
- Monitoring of nutritional intakes and serum transthyretin and albumin levels.
- Comparison of growth velocities (weight and MAC) with intrauterine rates.
Main Results:
- Abnormal weight measurements were more frequent than abnormal MAC measurements during hospitalization (48% vs 24%).
- Abnormal MAC:HC measurements were less frequent than abnormal weight/length for age values (25% vs 68%).
- MAC velocities exceeded weight gain velocities during weeks 2-4, aligning with or exceeding intrauterine rates, while weight gain was slower.
Conclusions:
- MAC and MAC:HC are valuable tools for assessing longitudinal growth in preterm infants.
- These measurements are less prone to overestimating malnourishment compared to weight-based indicators during periods of adequate protein-calorie intake.
- MAC and MAC:HC provide a more sensitive assessment of growth in preterm infants.
Abstract:
In order to study the usefulness of upper mid-arm circumference (MAC) and mid-arm circumference:head circumference ratio (MAC:HC) measurements in assessing longitudinal growth in hospitalized preterm infants, we prospectively measured weights, lengths, occipitofrontal head circumferences (OFC), MACs, MAC:HCs, weight/length for age, nutritional intakes, and serum transthyretin and albumin levels in 50 preterm, low-birth-weight, appropriate for gestational age newborn infants during their first 4 postnatal weeks and at hospital discharge. At some time during hospitalization, weight measurements were abnormal (greater than or equal to 2SD from the gestational age mean) in 48% of the infants as compared with 24% with abnormal MAC measurements (p = 0.002). Abnormal MAC:HCs occurred in 25% of the infants as compared with 68% with abnormal weight/length for age values (p less than 0.001). During weeks 2-4, when nutritional intakes were adequate and serum transthyretin and albumin levels were normal, mean weight gain velocity was less than intrauterine rates and was significantly slower than MAC velocities, which were at or greater than intrauterine rates (p less than 0.001). At discharge, when all infants were gaining weight at intrauterine rates, weight measurements were still abnormal in 28% of the infants as compared with 10% of infants who had abnormal MACs (p = 0.005). Similarly, only 12% of infants had abnormal MAC:HCs as compared with 25% of infants with abnormal weight/length for age values at discharge (p = 0.05). The MAC and MAC:HC are useful for assessing longitudinal growth in preterm infants since they do not overestimate the prevalence of malnourishment during periods of apparent protein-calorie sufficiency.