Acta Paediatr 81: 933-4. 1992
SHORT COMMUNICATION
Steatocrit test: normal range and physiological variations in preterm and low-birth-weight full-term newborns G Iacono', A Carroccio2, G Montalto*, F Cavataio', RA Gioeli3,AM Di Dato3, A Notarbartolo2, V Balsamo' and A Priolisi3 Ospedale Pediarrico "G. Di Crisrina"' Palermo. Cartedra di Parologia Medica2, Universira di Palermo and Carredra di Puericul~ura'. Universira di Palermo. Italy ~
In a recent study, we defined the range of steatocrit normal values in healthy infants during their first three months of life to facilitate the interpretation of the results obtained using the steatocrit method (1). However, it is well known that premature infants have difficulty in absorbing fat. To evaluate steatocrit behaviour in preterm and fullterm but small-for-gestational-age(SGA) neonates and to establish a range of steatocrit values for these two groups of patients, to be used as a reference, we studied 35 preterm neonates (18 males, 17 females) of 30-37 weeks gestation (group A). Mean birth weight was 21 15 g (range 1300-3250 g); none of these patients was sufferingfrom any congenital malformation and growth after birth was satisfactory, with a normal increase in weight curves. In addition, we studied 19 full-term SGA neonates (10 males, 9 females) (group B) with a mean weight of 2260 g (range 1900-2500 g): included in this group were neonates whose weight, with respect to their sex, was lower than the mean -2SD, according to the body weight-gestational age diagram appropriate to the neonatal population (2). The control group was composed of 35 healthy fullterm neonates (18 males, 17 females) (group C), with a mean birth weight appropriate for gestational age (AGA); 3331 & 408 g (range 2800-4000 g). All subjects in this study had been fed since birth with an adapted cow's milk formula containing the following per 100 g of powder: 12.5 g protein, 28 g lipids (1 1.8 g saturated fats, 12.7g unsaturated fats, 3.5 g linoleic acid), 55.5 g lactose and 2.5 g minerals. The preterm and SGA neonates received different amounts of milk, according to their individual needs. Daily fat intake ranged as follows: preterm infants: 1.4 to 1 1.2 g at 7 days, 6.2 to 16.8 g at 14 days, 11.2 to 25.5 g a t 21 days, 16.8 to 33.6 g a t 28 days; SGA neonates: 1.4 to 14 g a t 7 days, 8.4 to 16.8 g a t 14 days; in addition, part of their lipid requirement was administered as MCT (1 to 2 cc/day). All patients were tested with our modified version of the steatocrit micromethod (1). In the preterm infants the test was performed at 7, 14, 21 and 28 days after birth, while in the full-term SGA neonates it was performed only on day 7 and 14. In the healthy controls the test was performed at 7, 14, 21, 28, 60, 90 and 120 days after birth.
Statistical analysis of the data was performed using the chi-square test for contingency tables to compare frequencies. The Spearman coefficient of correlation was used to correlate steatocrit positivity with time and to evaluate the relationship between steatocrit values and weight at birth in all full-term infants. Range and median steatocrit values were also obtained. Table 1 shows the range and median steatocrit values. From day 14, the widest range of values was found in groups A and B; moreover, at all times during the first month, the median steatocrit values were higher in the full-term SGA neonates and in the preterm infants than in the controls. In group C neonates, the steatocrit tests performed at 60, 90 and 120 days after birth all gave a result lower than 2%. Table 2 shows the number of newborns with positive steatocrit values (above 2%) during the first month after birth in the three groups studied. The frequency of positive steatocrit values decreased progressively with time in group C only and the correlation with time was negative and significant (Spearman correlation coefficient = - 0.98; p < 0.001). In contrast, steatocrit values were positive in groups A and B until day 28 and 14 respectively, and no significant correlation with time was found. A comparison of the frequency of positivity in the three groups, using a chi-square test for contingency tables, showed that the difference was significant when controls were compared with preterm infants (Chi
Table 1. Median (range) steatocrit levels in the three groups studied on day 7, 14, 21 and 28 after birth.
Days after birth 7 ~~~
14
21
28
20 (7-37)
12 (6-35)
-
-
5 (0-23)
0 (0-28)
~
Preterm infants (n = 35) Median 14 14 Range (4-28) (1-33) Low-birth-weight infants (n = 19) Median 20 20 Range (5-33) (6-35) Term infants (n = 35) I1 7 Median Range (040) (0-27)
934
G Iacono et al.
ACTA PEDIATR 81 (1992)
Table 2. Number and percentage+95XI confidence limits (CL) in 35 preterm, 19 full-term SGA and 35 full-term AGA infants with positive steatocrit values.
Days after birth 7
14
21
28
Preterm infants No. 35 34 35 35 ‘Yo + CL 100 97+5.5 100 I00 Full-term SGA No. 19 19 %,+CL 100 100 Full-term AGA No. 32 25 23 16 91.4+5.4 71.4+ 14.9 65.7+ 15.7 45.7+16.5 %+CL Chi-square test for contingency tables: full-term AGA vs preterms p < 0.0001; full-term AGA vs SGAp < 0.05; full-term SGA vs preterms
not significant.
square = 52.432; p < 0.0001) and with full-term SGA neonates (chi square = 8.387; p < 0.05). Moreover, we evaluated the correlation between steatocrit values and weight of both the full-term AGA and SGA neonates. A statistically significant negative correlation was found on day 7 ( r = -0.374; p
SHORT COMMUNICATION
Steatocrit test: normal range and physiological variations in preterm and low-birth-weight full-term newborns G Iacono', A Carroccio2, G Montalto*, F Cavataio', RA Gioeli3,AM Di Dato3, A Notarbartolo2, V Balsamo' and A Priolisi3 Ospedale Pediarrico "G. Di Crisrina"' Palermo. Cartedra di Parologia Medica2, Universira di Palermo and Carredra di Puericul~ura'. Universira di Palermo. Italy ~
In a recent study, we defined the range of steatocrit normal values in healthy infants during their first three months of life to facilitate the interpretation of the results obtained using the steatocrit method (1). However, it is well known that premature infants have difficulty in absorbing fat. To evaluate steatocrit behaviour in preterm and fullterm but small-for-gestational-age(SGA) neonates and to establish a range of steatocrit values for these two groups of patients, to be used as a reference, we studied 35 preterm neonates (18 males, 17 females) of 30-37 weeks gestation (group A). Mean birth weight was 21 15 g (range 1300-3250 g); none of these patients was sufferingfrom any congenital malformation and growth after birth was satisfactory, with a normal increase in weight curves. In addition, we studied 19 full-term SGA neonates (10 males, 9 females) (group B) with a mean weight of 2260 g (range 1900-2500 g): included in this group were neonates whose weight, with respect to their sex, was lower than the mean -2SD, according to the body weight-gestational age diagram appropriate to the neonatal population (2). The control group was composed of 35 healthy fullterm neonates (18 males, 17 females) (group C), with a mean birth weight appropriate for gestational age (AGA); 3331 & 408 g (range 2800-4000 g). All subjects in this study had been fed since birth with an adapted cow's milk formula containing the following per 100 g of powder: 12.5 g protein, 28 g lipids (1 1.8 g saturated fats, 12.7g unsaturated fats, 3.5 g linoleic acid), 55.5 g lactose and 2.5 g minerals. The preterm and SGA neonates received different amounts of milk, according to their individual needs. Daily fat intake ranged as follows: preterm infants: 1.4 to 1 1.2 g at 7 days, 6.2 to 16.8 g at 14 days, 11.2 to 25.5 g a t 21 days, 16.8 to 33.6 g a t 28 days; SGA neonates: 1.4 to 14 g a t 7 days, 8.4 to 16.8 g a t 14 days; in addition, part of their lipid requirement was administered as MCT (1 to 2 cc/day). All patients were tested with our modified version of the steatocrit micromethod (1). In the preterm infants the test was performed at 7, 14, 21 and 28 days after birth, while in the full-term SGA neonates it was performed only on day 7 and 14. In the healthy controls the test was performed at 7, 14, 21, 28, 60, 90 and 120 days after birth.
Statistical analysis of the data was performed using the chi-square test for contingency tables to compare frequencies. The Spearman coefficient of correlation was used to correlate steatocrit positivity with time and to evaluate the relationship between steatocrit values and weight at birth in all full-term infants. Range and median steatocrit values were also obtained. Table 1 shows the range and median steatocrit values. From day 14, the widest range of values was found in groups A and B; moreover, at all times during the first month, the median steatocrit values were higher in the full-term SGA neonates and in the preterm infants than in the controls. In group C neonates, the steatocrit tests performed at 60, 90 and 120 days after birth all gave a result lower than 2%. Table 2 shows the number of newborns with positive steatocrit values (above 2%) during the first month after birth in the three groups studied. The frequency of positive steatocrit values decreased progressively with time in group C only and the correlation with time was negative and significant (Spearman correlation coefficient = - 0.98; p < 0.001). In contrast, steatocrit values were positive in groups A and B until day 28 and 14 respectively, and no significant correlation with time was found. A comparison of the frequency of positivity in the three groups, using a chi-square test for contingency tables, showed that the difference was significant when controls were compared with preterm infants (Chi
Table 1. Median (range) steatocrit levels in the three groups studied on day 7, 14, 21 and 28 after birth.
Days after birth 7 ~~~
14
21
28
20 (7-37)
12 (6-35)
-
-
5 (0-23)
0 (0-28)
~
Preterm infants (n = 35) Median 14 14 Range (4-28) (1-33) Low-birth-weight infants (n = 19) Median 20 20 Range (5-33) (6-35) Term infants (n = 35) I1 7 Median Range (040) (0-27)
934
G Iacono et al.
ACTA PEDIATR 81 (1992)
Table 2. Number and percentage+95XI confidence limits (CL) in 35 preterm, 19 full-term SGA and 35 full-term AGA infants with positive steatocrit values.
Days after birth 7
14
21
28
Preterm infants No. 35 34 35 35 ‘Yo + CL 100 97+5.5 100 I00 Full-term SGA No. 19 19 %,+CL 100 100 Full-term AGA No. 32 25 23 16 91.4+5.4 71.4+ 14.9 65.7+ 15.7 45.7+16.5 %+CL Chi-square test for contingency tables: full-term AGA vs preterms p < 0.0001; full-term AGA vs SGAp < 0.05; full-term SGA vs preterms
not significant.
square = 52.432; p < 0.0001) and with full-term SGA neonates (chi square = 8.387; p < 0.05). Moreover, we evaluated the correlation between steatocrit values and weight of both the full-term AGA and SGA neonates. A statistically significant negative correlation was found on day 7 ( r = -0.374; p
