INCREASED GONADOTROPIN LEVELS IN NEWBORN PREMATURE FEMALES TREATED BY PHOTOTHERAPY B. J. LEMAITRE*,P. L. TOUBASt, C. DREUX* and A. MINKOWSKI? * Laboratoire Central de Biochimie, H&pita] Saint-Louis, Paris and t lnstitut de Recherches Biologiques Foetales et Ntonatales, Hopital Port-Royal, Paris, France (Received 9 May 1978) SUMMARY A group of 16 premature infants (9 females and 7 males) who were treated with phototherapy because of jaundice were compared in respect of plasma gonadotropin levels to a control group of 10 premature infants (4 girls and 6 boys) who did not require phototherapy. Luteinizing hormone (LH) and follicle stimulating hormone (FSH) were measured by radioimmunoassay. During the third and fourth week of life, gonadotropins increased simultaneously in phototherapy treated females (FSH P < 0.001; LH P < O.Ol), reached high values (20 and 80mU/ml, respectively), stayed elevated during three weeks, then declined quickly to under lOmU/ml. In the group of treated males no significant rise in FSH and LH was observed. Constant phototherapy and/or the sudden stopping of this treatment in the jaundiced premature newborn female is responsible for a marked and transient elevation of gonadotropins.
INTRODUCTION
has been used in the treatment of jaundice of the newborn [l]. Side effects such as hyperthermia and ocular lesions can be avoided by careful monitoring of the temperature and by occluding the child’s eyes with a band [2]. It is known that light through retinal and extraretinal photoreceptors acts on neuroendocrine structures [3] influencing sexual maturation with changes in gonadotropin levels. Many workers have studied the changes of follicle-stimulating-hormone (FSH) and luteinizing-hormone (LH) during the first month of life [4-6] but few have studied the effects of continuous light exposure [7]. In order to determine if phototherapy was influencing any change in plasma FSH and LH levels, we have compared a group of 16 premature infants who had been treated with phototherapy to a control group of 10 premature infants who did not require phototherapy. This study presents additional data to preliminary results already published [S]. For many years phototherapy
MATERIAL AND METHODS
Twenty-six premature infants were studied. The gestational ages (G.A.) were between 27 and 36 weeks and weights were between 1100 and 2200 g. Four girls (G.A. mean + 1 SD. = 33.75 + 1.25) and six boys (G.A. mean f S.D. 34.83 f 1.60) who did not receive any phototherapy were used as a control group. Nine girls (GA mean f 1 S.D. = 33.22 f 2.00) and seven boys (GA mean + 1 S.D. = 30.19 + 2.75) were submitted to phototherapy within the first two weeks of life because of hyperbilirubinaemia. Continuous pho335
totherapy started when total bilirubinaemia was above 8-10mg/1OOml and continued as long as total bilirubinaemia was above 8 mg/lOO ml (the duration of phototherapy ranged between one and seven days depending upon the severity of jaundice). The infants were naked in an incubator and were exposed to a white light produced by five 20 watts fluorescent TRUE LITE TXC tubes located outside the incubator above the baby. The intensity of the light at the level of the skin was within a range of 2800-3300 lux. Their eyes were protected against direct exposure to tight by a black paper band and covered with gauze compresses. None of these newborns received an exchange transfusion. (1) Experimental protocol. In the treated newborn group, blood samples were taken before, or during, and after phototherapy, then once or twice a week during the 4 or 5 following weeks. In the control group, blood samples were taken at the time of birth, then once or twice a week during the hospitalisation. Blood samples in all of these newborns were taken when blood was withdrawn for other clinical indications. Blood was put into heparinized tubes, immediately centrifugated and plasma frozen at -20°C. (2) Measurement of plasma FSH ana’ LH. FSH and LH were measured according to the technique of Franchimont [9]. In order to eliminate inter-assay errors samples were assayed in a single FSH and a single LH assay using duplicate samples. The standards used were the Medical Research Council 68/40 for LH and 69/104 for FSH. Minimum detectable level of FSH and LH were 0.8 mu/ml. LH determinations during the first week of life were contaminated by cross-reacting HCG.
336
B. J. LEMAITRE et al. Table 1. Males: mean values and standard deviation of the plasma FSH and LH concentrations (mu/ml) are listed by week and compare the control group to the phototherapy treated group FSH mu/ml Week
No.
1
12 10 9 10
2 3 4
Control group Mean Range
SD.
Phototherapy treated group No. Mean SD. Range
1.00-4.80 l.cn&5.15 1.Kl-3.90 1.00-4.70
0.32 0.02 0.30 0.16
11 7 6 5
1.10-1.80 1.4&I .80 1.10-1.40 1.3s2.30
1.40 1.55 1.35 1.50
0.05 0.47 0.05 0.20
12 6 6 5
1.20-6.70 1.30-8.10 1.20-5.00 4.00-5.20
6.50 3.20 2.20 4.95
0.68 1.15 0.50 0.40
1.70 1.70 1.55 2.10
LH mu/ml 11 11 9 7
1
2 3 4
1.OO-8.00 1X0-9.60 I .OO-3.50 1.00-4.00
2.50 3.40 2.10 2.10
Intra-assay coefficient variation was less than 10% in the FSH and LH assays at a level of 5 mu/ml
and less than 2% at a level of 4OmU/ml. Results were analysed by the non-parametric statistical Kolmogorov-Smimov test [lo, 111. RESULTS
(1) Males (Table 1) In the control group did not change during stayed below 5 mu/ml LH. In the phototherapy rise in FSH or LH was
plasma FSH and LH levels the first month of life and for FSH and lOmU/ml for treated group no significant observed (P > 0.1).
(2) Females (Table 2) In the control group FSH levels rose after the first
0.48 0.95 0.30 0.45
week (P -z O.OOS),but were below 16mU/ml during the first month of life. In the treated group FSH levels increased significantly after the first week of life (P < 0.001) reached high levels (80mU/ml), stayed elevated for three weeks and then decreased quickly. When compared to the control group the FSH levels were markedly higher in the treated group (P < 0.001). No significant change in the plasma LH levels was detectable during the first month of life (P > 0.1) in the control group and levels were lower than 5.35 mu/ml. A significant rise in LH appeared in the treated group after the first week (P < 0.01). but the peak concentrations were below 25 mu/ml. LH levels were significantly higher in the phototherapy treated female group than in the control group during the third and fourth week of life (P < 0.001).
Table 2. Females: mean values and standard deviation of the plasma FSH and LH concentrations (mu/ml) are listed by week and compare the control group to the phototherapy treated group FSH mu/ml
Week
No.
1 2 3 4
6 6 5 4
Control group Range Mean 1.40-4.00 1.40-8.40 1.40-8.00 2.20-16.00
1.95 5.50” 3.70” 7.60”
Phototherapy Range
treated group Mean SD.
SD.
No.
0.43 1.08 1.45 2.95
15 7 13 12
I .OO-8.40 17.00-68.00 14.00-79.00 7.00-55.00
3.25 36.35& 39.55w 34.85b*
0.66 8.50 5.77 2.73
12 7 12 11
1.00-5.50 2.00-5.75 2.70-25.00 1.20-l 7.00
2.70 3.30 9.05’f 10.4oE*
0.44 0.64 2.10 4.67
LH mu/ml 1 2 3 4
6 6 5 4
“Comparison
1.00-5.35 1.50-2.40 1.00-2.70
1.20-2.80
2.70 2.00 1.50 2.15
0.62 0.20 0.30 0.25
for FSH mean between weeks 2.3.4 and week 1 in the control group:
P < 0.005. h Comparison for FSH mean between weeks 2.3.4 and week 1 in the phototherapy group: P < 0.001. ‘Comparison for LH mean between weeks 2.3.4’and week 1 in the phototherapy group: P < 0.01. l Comparison for FSH and LH mean between control group and phototherapy group during week 2.3.4: P < 0.001.
treated treated treated
Gonadotropin
levels in newborn premature females
DISCUSSION
Our results agree with previous reports of a sex
difference in serum gonadotropins. In controls plasma concentrations of FSH were higher in girls than in boys, there was no difference for LH, which is generally higher in term female than in term male newborns during the first months of life [46]. It is likely that gestational age plays an important role since all newborns in our study are premature. Our results show that the increase of gonadotropins is influenced by light and confirm our preliminary finding [S]. It is difficult to speculate about the mechanism of the observed phenomenon. The role of jaundice cannot be completely rule out. Furthermore, due to ethical reasons no adequate control groups, i.e. children with occluded eyes or jaundice without phototherapy, were available and the small amount of plasma drawn did not allow oestradiol and testosterone assays. In the newborn female high amounts of gonadotropins are present in the pituitary [12]. The high plasma levels of FSH and LH found after phototherapy suggest a release of this important store after stimulation of neuroendorcrine structures by light. During phototherapy light seems to act mainly through the skin using a non retinal pathway since the eyes were occluded [13]. Some authors showed that phototherapy induce an increase of plasma growth hormone levels (141. From a clinical point of view these elevated gonadotropin levels may be responsible for some deleterious effects, especially during critical periods of growth and sexual development. REFERENCES
1. Cohn J., Alison F., Char& J., Narbouton R., Sarrut S. and Satge P.: Bilan de la photothtrapie dans un
337
centre de prtmaturb. Ann. Phdiat. 21 (1974) 501-506. 2. Drew J. H., Marriage K. J., Bayle V. V., Bajraszewski E. and McNamara J. M.: Phototherapy short an long term complicatjons. Archs. Dis. Child 51 (19761 454-458. 3. Wurtman R. J.: The effects of light on man and other mammals. Ann. Rev. Physiol. 1139 (1975) 467-483. 4. Winter J. S. D., Faiman C.. Hobson W. C.. Peasad A. V. and Reyes F. 1.: Pituitary gonadal relation in infancy. I. Patterns of serum gonadotropin concentrations from birth to four years of age in man and chimpanzee. .I. c/in. Endocr. Metah. 40 (1975) 545-55 I. 5. Faiman C. and Winter J. S. D.: Differences in gonadotropin concentrations in infancy. Nature 232 (1971) 130. 6. Lee P. A., Migdley A. R. and Jaffe R. B.: Regulation of human gonadotropins. VI serum follicle-stimulating and luteinizing hormone determination in children. J. c/in. Endocr. Metab. 31 (1970) 248-253. 7. Dacou-Voutetakis C. and Anagnostakis D.: Phototherapy and serum LH levels in newborns. Ped. Res. (1976). 8. Lemaitre B., Toubas P. L., Guillot M.. Dreux C. and Relier J. P.: Changes of serum gonadotropin concentrations in premature babies submitted to phototherapy. Biol. Neonafe 32 (1977) 113-118. 9. Franchimont P.: Protein and Polypeptide Hormones., Excerpta Medica Foundation, Margoulies, Amsterdam (1968) p. 99. 10. Siegel S.: The Ko/mogoro~+Ymirnor Tests Two Sample Tesr. McGraw-Hill, New York (1976) p. 127. 11. Goodman L. A.: Kolmogorov-Smirnov tests for psychological research. Psychol. Bull. 51 (1973) 160. 12. Grumbach M. M. and Kaplan S. L.: Fetal Neonatal Physiology, proceedings of the Sir Barcroft Centery Symposium, Cambridge University Press (1972) p. 462. 13. Zweig M., Snyder S. M. and Axelrod J.: Evidence of a non retinal pathways of light to the pineal gland of newborn rats. Proc. natn. Acad. Sci. U.S.A. 56 (1966) 515-520. 14. Muhlendahl K. E. and Ballowite L.: Growth hormone and cortisol in neonates during phototherapy Z. Kinderheik 119 (1975) 5358.
INTRODUCTION
has been used in the treatment of jaundice of the newborn [l]. Side effects such as hyperthermia and ocular lesions can be avoided by careful monitoring of the temperature and by occluding the child’s eyes with a band [2]. It is known that light through retinal and extraretinal photoreceptors acts on neuroendocrine structures [3] influencing sexual maturation with changes in gonadotropin levels. Many workers have studied the changes of follicle-stimulating-hormone (FSH) and luteinizing-hormone (LH) during the first month of life [4-6] but few have studied the effects of continuous light exposure [7]. In order to determine if phototherapy was influencing any change in plasma FSH and LH levels, we have compared a group of 16 premature infants who had been treated with phototherapy to a control group of 10 premature infants who did not require phototherapy. This study presents additional data to preliminary results already published [S]. For many years phototherapy
MATERIAL AND METHODS
Twenty-six premature infants were studied. The gestational ages (G.A.) were between 27 and 36 weeks and weights were between 1100 and 2200 g. Four girls (G.A. mean + 1 SD. = 33.75 + 1.25) and six boys (G.A. mean f S.D. 34.83 f 1.60) who did not receive any phototherapy were used as a control group. Nine girls (GA mean f 1 S.D. = 33.22 f 2.00) and seven boys (GA mean + 1 S.D. = 30.19 + 2.75) were submitted to phototherapy within the first two weeks of life because of hyperbilirubinaemia. Continuous pho335
totherapy started when total bilirubinaemia was above 8-10mg/1OOml and continued as long as total bilirubinaemia was above 8 mg/lOO ml (the duration of phototherapy ranged between one and seven days depending upon the severity of jaundice). The infants were naked in an incubator and were exposed to a white light produced by five 20 watts fluorescent TRUE LITE TXC tubes located outside the incubator above the baby. The intensity of the light at the level of the skin was within a range of 2800-3300 lux. Their eyes were protected against direct exposure to tight by a black paper band and covered with gauze compresses. None of these newborns received an exchange transfusion. (1) Experimental protocol. In the treated newborn group, blood samples were taken before, or during, and after phototherapy, then once or twice a week during the 4 or 5 following weeks. In the control group, blood samples were taken at the time of birth, then once or twice a week during the hospitalisation. Blood samples in all of these newborns were taken when blood was withdrawn for other clinical indications. Blood was put into heparinized tubes, immediately centrifugated and plasma frozen at -20°C. (2) Measurement of plasma FSH ana’ LH. FSH and LH were measured according to the technique of Franchimont [9]. In order to eliminate inter-assay errors samples were assayed in a single FSH and a single LH assay using duplicate samples. The standards used were the Medical Research Council 68/40 for LH and 69/104 for FSH. Minimum detectable level of FSH and LH were 0.8 mu/ml. LH determinations during the first week of life were contaminated by cross-reacting HCG.
336
B. J. LEMAITRE et al. Table 1. Males: mean values and standard deviation of the plasma FSH and LH concentrations (mu/ml) are listed by week and compare the control group to the phototherapy treated group FSH mu/ml Week
No.
1
12 10 9 10
2 3 4
Control group Mean Range
SD.
Phototherapy treated group No. Mean SD. Range
1.00-4.80 l.cn&5.15 1.Kl-3.90 1.00-4.70
0.32 0.02 0.30 0.16
11 7 6 5
1.10-1.80 1.4&I .80 1.10-1.40 1.3s2.30
1.40 1.55 1.35 1.50
0.05 0.47 0.05 0.20
12 6 6 5
1.20-6.70 1.30-8.10 1.20-5.00 4.00-5.20
6.50 3.20 2.20 4.95
0.68 1.15 0.50 0.40
1.70 1.70 1.55 2.10
LH mu/ml 11 11 9 7
1
2 3 4
1.OO-8.00 1X0-9.60 I .OO-3.50 1.00-4.00
2.50 3.40 2.10 2.10
Intra-assay coefficient variation was less than 10% in the FSH and LH assays at a level of 5 mu/ml
and less than 2% at a level of 4OmU/ml. Results were analysed by the non-parametric statistical Kolmogorov-Smimov test [lo, 111. RESULTS
(1) Males (Table 1) In the control group did not change during stayed below 5 mu/ml LH. In the phototherapy rise in FSH or LH was
plasma FSH and LH levels the first month of life and for FSH and lOmU/ml for treated group no significant observed (P > 0.1).
(2) Females (Table 2) In the control group FSH levels rose after the first
0.48 0.95 0.30 0.45
week (P -z O.OOS),but were below 16mU/ml during the first month of life. In the treated group FSH levels increased significantly after the first week of life (P < 0.001) reached high levels (80mU/ml), stayed elevated for three weeks and then decreased quickly. When compared to the control group the FSH levels were markedly higher in the treated group (P < 0.001). No significant change in the plasma LH levels was detectable during the first month of life (P > 0.1) in the control group and levels were lower than 5.35 mu/ml. A significant rise in LH appeared in the treated group after the first week (P < 0.01). but the peak concentrations were below 25 mu/ml. LH levels were significantly higher in the phototherapy treated female group than in the control group during the third and fourth week of life (P < 0.001).
Table 2. Females: mean values and standard deviation of the plasma FSH and LH concentrations (mu/ml) are listed by week and compare the control group to the phototherapy treated group FSH mu/ml
Week
No.
1 2 3 4
6 6 5 4
Control group Range Mean 1.40-4.00 1.40-8.40 1.40-8.00 2.20-16.00
1.95 5.50” 3.70” 7.60”
Phototherapy Range
treated group Mean SD.
SD.
No.
0.43 1.08 1.45 2.95
15 7 13 12
I .OO-8.40 17.00-68.00 14.00-79.00 7.00-55.00
3.25 36.35& 39.55w 34.85b*
0.66 8.50 5.77 2.73
12 7 12 11
1.00-5.50 2.00-5.75 2.70-25.00 1.20-l 7.00
2.70 3.30 9.05’f 10.4oE*
0.44 0.64 2.10 4.67
LH mu/ml 1 2 3 4
6 6 5 4
“Comparison
1.00-5.35 1.50-2.40 1.00-2.70
1.20-2.80
2.70 2.00 1.50 2.15
0.62 0.20 0.30 0.25
for FSH mean between weeks 2.3.4 and week 1 in the control group:
P < 0.005. h Comparison for FSH mean between weeks 2.3.4 and week 1 in the phototherapy group: P < 0.001. ‘Comparison for LH mean between weeks 2.3.4’and week 1 in the phototherapy group: P < 0.01. l Comparison for FSH and LH mean between control group and phototherapy group during week 2.3.4: P < 0.001.
treated treated treated
Gonadotropin
levels in newborn premature females
DISCUSSION
Our results agree with previous reports of a sex
difference in serum gonadotropins. In controls plasma concentrations of FSH were higher in girls than in boys, there was no difference for LH, which is generally higher in term female than in term male newborns during the first months of life [46]. It is likely that gestational age plays an important role since all newborns in our study are premature. Our results show that the increase of gonadotropins is influenced by light and confirm our preliminary finding [S]. It is difficult to speculate about the mechanism of the observed phenomenon. The role of jaundice cannot be completely rule out. Furthermore, due to ethical reasons no adequate control groups, i.e. children with occluded eyes or jaundice without phototherapy, were available and the small amount of plasma drawn did not allow oestradiol and testosterone assays. In the newborn female high amounts of gonadotropins are present in the pituitary [12]. The high plasma levels of FSH and LH found after phototherapy suggest a release of this important store after stimulation of neuroendorcrine structures by light. During phototherapy light seems to act mainly through the skin using a non retinal pathway since the eyes were occluded [13]. Some authors showed that phototherapy induce an increase of plasma growth hormone levels (141. From a clinical point of view these elevated gonadotropin levels may be responsible for some deleterious effects, especially during critical periods of growth and sexual development. REFERENCES
1. Cohn J., Alison F., Char& J., Narbouton R., Sarrut S. and Satge P.: Bilan de la photothtrapie dans un
337
centre de prtmaturb. Ann. Phdiat. 21 (1974) 501-506. 2. Drew J. H., Marriage K. J., Bayle V. V., Bajraszewski E. and McNamara J. M.: Phototherapy short an long term complicatjons. Archs. Dis. Child 51 (19761 454-458. 3. Wurtman R. J.: The effects of light on man and other mammals. Ann. Rev. Physiol. 1139 (1975) 467-483. 4. Winter J. S. D., Faiman C.. Hobson W. C.. Peasad A. V. and Reyes F. 1.: Pituitary gonadal relation in infancy. I. Patterns of serum gonadotropin concentrations from birth to four years of age in man and chimpanzee. .I. c/in. Endocr. Metah. 40 (1975) 545-55 I. 5. Faiman C. and Winter J. S. D.: Differences in gonadotropin concentrations in infancy. Nature 232 (1971) 130. 6. Lee P. A., Migdley A. R. and Jaffe R. B.: Regulation of human gonadotropins. VI serum follicle-stimulating and luteinizing hormone determination in children. J. c/in. Endocr. Metab. 31 (1970) 248-253. 7. Dacou-Voutetakis C. and Anagnostakis D.: Phototherapy and serum LH levels in newborns. Ped. Res. (1976). 8. Lemaitre B., Toubas P. L., Guillot M.. Dreux C. and Relier J. P.: Changes of serum gonadotropin concentrations in premature babies submitted to phototherapy. Biol. Neonafe 32 (1977) 113-118. 9. Franchimont P.: Protein and Polypeptide Hormones., Excerpta Medica Foundation, Margoulies, Amsterdam (1968) p. 99. 10. Siegel S.: The Ko/mogoro~+Ymirnor Tests Two Sample Tesr. McGraw-Hill, New York (1976) p. 127. 11. Goodman L. A.: Kolmogorov-Smirnov tests for psychological research. Psychol. Bull. 51 (1973) 160. 12. Grumbach M. M. and Kaplan S. L.: Fetal Neonatal Physiology, proceedings of the Sir Barcroft Centery Symposium, Cambridge University Press (1972) p. 462. 13. Zweig M., Snyder S. M. and Axelrod J.: Evidence of a non retinal pathways of light to the pineal gland of newborn rats. Proc. natn. Acad. Sci. U.S.A. 56 (1966) 515-520. 14. Muhlendahl K. E. and Ballowite L.: Growth hormone and cortisol in neonates during phototherapy Z. Kinderheik 119 (1975) 5358.
