9 1992 by The Humana Press, Inc. All rights of any nature, whatsoever, reserved. 0163-4984/92/3201-3-0047 $02.00
Chromium Status of Full-Term and Preterm Newborns DOMINIQUE BOUGLE,* FRANCOIS BUREAU,JOEL VOIRIN, DOMINIQUE NEUVILLE,MICHELDROSDOWSKY, AND JEAN-FRANCOIS DUHAMEL Departement de P~diatrie et Laboratoire de Biochimie A, CHU de Caen, France
ABSTRACT In order to obtain reference values from normal babies, Cr status of full-term newborns has been studied. Plasma and urine values were (mean • SEM) 0.7 _+ 0.1 #,g/L and 0.9 +_ 0.3 ~g/L, respectively, for the first month of life (n = 19), and 0.6 • 0.1 ~g/L and 0.8 _+ 0.2 I*g/L for the second-to-third-month period (11 = 31). Premature newborns (gestational age 28-36 wk) were compared to these control values; concentrations were 0.9 _+ 0.1 I*g/L and 1.1 _+ 0.2 btg/L for the first month 01 = 47), and 1.0 _+ 0.2 ~g/L and 1.5 _+ 0.3 I~g/L for the second to third months (it = 27). For the whole group, there was a positive correlation between plasma and urine concentrations (p = 0.0001); multiple regression analysis was performed between plasma levels and gestational age at birth (p = -0.002) and postnatal age (NS). Plasma levels of prematures and full terms were statistically different (p = 0.03) only for the second- to third-month period. It is suggested that these high Cr levels result from high dietary intakes and/or high absorption rates. Index Entries: Chromium; formulas; human milk; plasma; urine; full-term newborn; preterm newborn.
INTRODUCTION C h r o m i u m (Cr) is linked to nucleic acids a n d is i n v o l v e d in several metabolic p a t h w a y s , i.e., p r o t e i n a n d fatty acid synthesis, a n d c a r b o h y *Author to whom all correspondence and reprint requests should be addressed. Biological Trace Element Research
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Vol. 32, 1992
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Bougle et al.
drates metabolism (1), which could make it an essential trace element for a growing organism. Indeed Cr supplementation has been shown to improve growth of deficient, malnourished children (2) and rats (3). However, only a few Cr studies have been devoted to newborns or children. Some data suggest a risk of Cr deficiency during the pregnancy (4-6). Cr is present in the fetal liver (7,8). Plasma Cr levels of cord and mother blood have been found similar (9). Premature newborns have displayed lower cord blood and hair concentrations than full terms (10,11). Therefore, premature newborns could be at risk of developing Cr deficiency. Analytical instrumentation and procedures have extensively improved during the last few years (1). Therefore, the aim of this study was to define our own normal values of Cr concentrations in full-term babies to compare them with preterm levels. Owing to this analytical evolution, we were also able to give more accurate values of our previously reported Cr concentrations of infant formulas and human milk (12,13).
SUBJECTS AND METHODS Plasma and urine samples were obtained from 1-88-d-old babies: 50 were full terms, and 74 were preterms (gestational age at birth 28--36 wk). Almost all of them were formula fed. Blood was collected in the morning before a feed, in polypropylene containers. These tubes had been previously checked and found to be free of Cr contamination. They have also been used for sample preparation and storage. After drawing, blood was centrifuged and kept frozen until analysis. The determination of Cr concentration was made on I + 1 (Triton 100 plus Mg [No312 0.05 rag/L) diluted samples by atomic absorption spectrometry (Perkin Elmer 3030 with Zeeman effect). An aliquot was delivered to pyrocoated graphite tubes and L'vov platforms (Perkin Elmer) by an auto sampler. The detection wavelength was 357 rim. Graphite furnace temperature program was: drying 140~ (20 s), ashing 1300~ (15 s), and atomization 2500~ (5 s). The Cr standard used was Cr Titrisol (Merck Lab). Routine reference materials were Urine Metals Control (Levels 1 and 2) (BIO. RAD, Munich) and Seronorm trace elements (NYCOMED, Sweden). Cr concentrations were also determined in 3 low-birth weight formulas, 16 standard formulas, and 8 human milk samples. Four or five batches of each formula were assayed.
RESULTS Infant Cr concentrations are given in Table 1. The whole group plasma and urine levels displayed a strong positive correlation (p = 0.0001). A multiple regression analysis showed that Cr plasma levels Biological Trace Element Research
Vol. 32, 1992
Chromium Status of Newborns
49
Table 1 Cr Status of Full-Term and Preterm Infants"
First month Full term Preterm
Plasma Urine Plasma Urine
0.7 0.9 0.9 1.1
+ 0.1 (19) + 0.3 _+ 0.1 (47) _+ 0.2
Second and third months 0.6 0.8 1.0 1.5
-+ 0 (31) + 0.2 _+ 0.2 (27) _+ 0.3
"Mean +_ SEM (n); ~g/L.
were negatively correlated with gestational age at birth (p = -0,002) (Fig. 1), whereas no correlation was found with postnatal age. Full-term and preterm Cr plasma levels did not differ during the first month of life and displayed a statistical difference during the second-tothird month period (p = 0,03). Mean concentration of low-birth weight infant formulas was (mean _+ SEM [range]) 6.5 p~g/L [3.6-8], of standard formulas 6.4 _+ 0.8 ~g/L, and of h u m a n milk 1.2 _+ 0.4 txg/L.
DISCOSSION Cr levels at birth have been found to be lower in preterm than in full term babies (10,11). In addition, prematures are exposed to stress and severe illness, which could increase Cr losses (1) and lead to Cr deficiency. According to its k n o w n consequences in h u m a n (14,15) and animal (1), Cr deficiency could contribute to the decreased glucose tolerance, slow growth, and impaired nerve maturation often found in prematures. However, data from normal infants were missing. This study gives usual plasma concentrations of formula-fed babies throughout the first 3 mo. These values (0.6-0.7 ~g/L) appear to be slightly higher than currently accepted norms for adults, which are close to 0.12-0.13 t*g/L (16) and in any case
Chromium Status of Full-Term and Preterm Newborns DOMINIQUE BOUGLE,* FRANCOIS BUREAU,JOEL VOIRIN, DOMINIQUE NEUVILLE,MICHELDROSDOWSKY, AND JEAN-FRANCOIS DUHAMEL Departement de P~diatrie et Laboratoire de Biochimie A, CHU de Caen, France
ABSTRACT In order to obtain reference values from normal babies, Cr status of full-term newborns has been studied. Plasma and urine values were (mean • SEM) 0.7 _+ 0.1 #,g/L and 0.9 +_ 0.3 ~g/L, respectively, for the first month of life (n = 19), and 0.6 • 0.1 ~g/L and 0.8 _+ 0.2 I*g/L for the second-to-third-month period (11 = 31). Premature newborns (gestational age 28-36 wk) were compared to these control values; concentrations were 0.9 _+ 0.1 I*g/L and 1.1 _+ 0.2 btg/L for the first month 01 = 47), and 1.0 _+ 0.2 ~g/L and 1.5 _+ 0.3 I~g/L for the second to third months (it = 27). For the whole group, there was a positive correlation between plasma and urine concentrations (p = 0.0001); multiple regression analysis was performed between plasma levels and gestational age at birth (p = -0.002) and postnatal age (NS). Plasma levels of prematures and full terms were statistically different (p = 0.03) only for the second- to third-month period. It is suggested that these high Cr levels result from high dietary intakes and/or high absorption rates. Index Entries: Chromium; formulas; human milk; plasma; urine; full-term newborn; preterm newborn.
INTRODUCTION C h r o m i u m (Cr) is linked to nucleic acids a n d is i n v o l v e d in several metabolic p a t h w a y s , i.e., p r o t e i n a n d fatty acid synthesis, a n d c a r b o h y *Author to whom all correspondence and reprint requests should be addressed. Biological Trace Element Research
47
Vol. 32, 1992
48
Bougle et al.
drates metabolism (1), which could make it an essential trace element for a growing organism. Indeed Cr supplementation has been shown to improve growth of deficient, malnourished children (2) and rats (3). However, only a few Cr studies have been devoted to newborns or children. Some data suggest a risk of Cr deficiency during the pregnancy (4-6). Cr is present in the fetal liver (7,8). Plasma Cr levels of cord and mother blood have been found similar (9). Premature newborns have displayed lower cord blood and hair concentrations than full terms (10,11). Therefore, premature newborns could be at risk of developing Cr deficiency. Analytical instrumentation and procedures have extensively improved during the last few years (1). Therefore, the aim of this study was to define our own normal values of Cr concentrations in full-term babies to compare them with preterm levels. Owing to this analytical evolution, we were also able to give more accurate values of our previously reported Cr concentrations of infant formulas and human milk (12,13).
SUBJECTS AND METHODS Plasma and urine samples were obtained from 1-88-d-old babies: 50 were full terms, and 74 were preterms (gestational age at birth 28--36 wk). Almost all of them were formula fed. Blood was collected in the morning before a feed, in polypropylene containers. These tubes had been previously checked and found to be free of Cr contamination. They have also been used for sample preparation and storage. After drawing, blood was centrifuged and kept frozen until analysis. The determination of Cr concentration was made on I + 1 (Triton 100 plus Mg [No312 0.05 rag/L) diluted samples by atomic absorption spectrometry (Perkin Elmer 3030 with Zeeman effect). An aliquot was delivered to pyrocoated graphite tubes and L'vov platforms (Perkin Elmer) by an auto sampler. The detection wavelength was 357 rim. Graphite furnace temperature program was: drying 140~ (20 s), ashing 1300~ (15 s), and atomization 2500~ (5 s). The Cr standard used was Cr Titrisol (Merck Lab). Routine reference materials were Urine Metals Control (Levels 1 and 2) (BIO. RAD, Munich) and Seronorm trace elements (NYCOMED, Sweden). Cr concentrations were also determined in 3 low-birth weight formulas, 16 standard formulas, and 8 human milk samples. Four or five batches of each formula were assayed.
RESULTS Infant Cr concentrations are given in Table 1. The whole group plasma and urine levels displayed a strong positive correlation (p = 0.0001). A multiple regression analysis showed that Cr plasma levels Biological Trace Element Research
Vol. 32, 1992
Chromium Status of Newborns
49
Table 1 Cr Status of Full-Term and Preterm Infants"
First month Full term Preterm
Plasma Urine Plasma Urine
0.7 0.9 0.9 1.1
+ 0.1 (19) + 0.3 _+ 0.1 (47) _+ 0.2
Second and third months 0.6 0.8 1.0 1.5
-+ 0 (31) + 0.2 _+ 0.2 (27) _+ 0.3
"Mean +_ SEM (n); ~g/L.
were negatively correlated with gestational age at birth (p = -0,002) (Fig. 1), whereas no correlation was found with postnatal age. Full-term and preterm Cr plasma levels did not differ during the first month of life and displayed a statistical difference during the second-tothird month period (p = 0,03). Mean concentration of low-birth weight infant formulas was (mean _+ SEM [range]) 6.5 p~g/L [3.6-8], of standard formulas 6.4 _+ 0.8 ~g/L, and of h u m a n milk 1.2 _+ 0.4 txg/L.
DISCOSSION Cr levels at birth have been found to be lower in preterm than in full term babies (10,11). In addition, prematures are exposed to stress and severe illness, which could increase Cr losses (1) and lead to Cr deficiency. According to its k n o w n consequences in h u m a n (14,15) and animal (1), Cr deficiency could contribute to the decreased glucose tolerance, slow growth, and impaired nerve maturation often found in prematures. However, data from normal infants were missing. This study gives usual plasma concentrations of formula-fed babies throughout the first 3 mo. These values (0.6-0.7 ~g/L) appear to be slightly higher than currently accepted norms for adults, which are close to 0.12-0.13 t*g/L (16) and in any case
