Normal growth patterns in rats, by Z score.

Malnutrition is one of the most important causes of normal growth disruptio n. Anthropometric methods are highly valuable in clinic pediatric diagnosis to determine the nutritional status of children and as recovery monitoring . In previous studies, we have demonstrated taht the standards weight-age, height-age and weight-height of growing rats had similar distribution to th ose in normal children. However, to improve the diagnostic effectiveness of anthropometric information, stadistical analysis to normally and non-norma lly distributed variables should be applied. One hundred Wistar rats (50 ma le and 50 female rats) from weaning (day = 25, weight = 35-40 g) to 70 days of age were fed with a commercial diet. Water and diet were offered "ad li bitum". Body weight and height were recorded every two or four days, respec tively. Percentiles of weight vs age, height vs age and weight vs height we re plotted for male and female rats. The stadistical criterion for classify ing the anthropometric measurements into nutritional categories was based o n percentiles cutoff and Z-score. The Z-score was calculated acording to: Z = (standard mean value-subject value/standard deviation of standard). The statistical anthropometric categories of growing rats were similar to those obtained in children. This evidence suggest that the rat can be used as an experimental model to infer and predict the nutritional response in childr en.