Nutrition Z Score

An alternative way to express height, weight, and weight for height is Z score, which denotes units of standard deviation from the median. It allows the clinician to locate an observation on the normal curve by the number of standard deviations it is from the center of the curve, and thus

STATURE !N INCHES 335 364 374 30.4 41J 43J 453 A72 tUS 513 SÏ1 SS I 57.1 59,1 61X1

STATURE !N INCHES 335 364 374 30.4 41J 43J 453 A72 tUS 513 SÏ1 SS I 57.1 59,1 61X1

Score Pediatric

85 90 95 100 105 110 115 1») 125 130 13$ 140 145 150 155 STATURE IN CM

Figure 2-12. Weight by stature percentiles for prepubescent boys.

85 90 95 100 105 110 115 1») 125 130 13$ 140 145 150 155 STATURE IN CM

Figure 2-12. Weight by stature percentiles for prepubescent boys.

detect movement toward or away from the median, which is more sensitive than percentile changes. This is especially useful in cases that lie outside the percentiles (ie. below the 5th or above the 95th percentile). The World Health Organization recommends using Z scores, especially when describing groups of subjects.s The Z score is calculated as follows:

actual median anthropometric value reference value

standard deviation

For example, for a 2-year-old male with cystic fibrosis whose weight is 10 kg (5th percentile):

Subsequent to nutrition evaluation, a feeding gastrostomy was placed, and night enteral feedings were instituted. When seen at l-month follow-up (age 2 years and I month), his weight was 10.6 kg. and his Z score is as follows:

Although still below the median for age. his weight at age 2 years and I month is moving toward the median (ie. showing improvement).

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