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Original Studies |
INSERM U-457 (D.J., J.L., P.C., C.L.-M.), and the Department of Hormonology and Biochemistry (D.C.), Hôpital R. Debré, 75019 Paris, France
Address all correspondence and requests for reprints to: Dr. D. Jaquet, INSERM U-457, Hôpital R. Debré, 48 boulevard Sérurier, 75019 Paris, France. E-mail: djacquet{at}infobiogen.fr
| Abstract |
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4-androstenedione
(2.26 ± 0.68 vs. 2.24 ± 0.55 ng/mL;
P = 0.76), dehydroepiandrosterone sulfate
(2294 ± 1117 vs. 2489 ± 1235 ng/mL;
P = 0.24), testosterone (0.82 ± 0.85
vs. 0.70 + 0.26 ng/mL; P = 0.80), or
serum sex hormone-binding protein concentrations (45.5 ± 28.2
vs. 53.1 ± 30.3 nmol/L; P =
0.27). In both IUGR and control groups, sex hormone-binding protein
correlated negatively with fasting insulin (r = -0.23;
P = 0.03 and r = -0.26; P
= 0.05), but serum androgen levels did not correlate with insulin. In
summary, hyperinsulinemia observed in young women born with IUGR is not
associated with hyperandrogenism. Consequently, our results do not
support the hypothesis of a common in utero programming
of hyperandrogenism and hyperinsulinemia. | Introduction |
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When studying the long term metabolic consequences of intrauterine growth retardation (IUGR) in a case/control study, we observed hyperinsulinemia during an oral glucose tolerance test (OGTT) and peripheral insulin resistance in young IUGR-born women (4, 5).
Hyperinsulinemia and insulin resistance are common features of FOH (6, 7, 8). The mechanism underlying the relation between hyperandrogenism and insulin resistance or hyperinsulinemia remains unresolved. However, it has been demonstrated that insulin increases the androgen response to LH in rodent and human ovary (9, 10). Insulin also increases androgen activity through down-regulation of the sex hormone-binding protein (SHBP) (11, 12).
The aim of the present study was to investigate whether IUGR-born women demonstrate hyperandrogenism compared with controls by recording clinical characteristics usually associated with hyperandrogenism and measuring serum androgen concentrations.
| Subjects and Methods |
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All women were selected according to their growth status at
birth. Subjects were identified from a population-based registry of the
metropolitan area of the city of Haguenau in France. This registry
recorded information on all pregnancies, deliveries, and perinatal
events in the area from 19711985 (13). Local standard growth curves
by gestational age were derived from all live births registered. Our
cohort was of all female singleton subjects born full term (
37 weeks)
during 19711978 with IUGR (weight and/or height below the 3rd
percentile for gestational age and gender, according to the local
standard growth curve; n = 241). Control subjects were selected as
the next full-term singleton female in the registry, with weight
between the 25th and 75th percentiles (n = 225). Fifty-five
percent of the IUGR-born women (n = 133) and 67% of the control
women (n = 151) agreed to participate in the study. Reasons for
nonparticipation have been previously reported, and birth data did not
significantly differ between IUGR-born and control women who agreed or
did not agree to participate (4). Gestational age did not significantly
differ between the two groups (39.7 ± 1.2 vs.
39.9 ± 1.2 weeks). As expected, weight and height at birth were
significantly lower in the IUGR group than in the control group
[2550 ± 334 vs. 3410 ± 216 g
(P = 0.0001) and 47 ± 2.1 vs.
50.4 ± 0.8 cm (P = 0.0001)].
In the present study, exclusion criteria included pregnancy, congenital adrenal hyperplasia, Cushings syndrome, hyperprolactinemia, and thyroid dysfunction. Three women in the IUGR group were excluded for pregnancy (n = 1) and nonclassic adrenal hyperplasia (n = 2). One woman in the control group was excluded for thyroid dysfunction.
The IUGR group included 130 women, and the control group contained 150, all aged 1623 yr. As functional hyperandrogenism predisposes to the use of hormonal therapy, we included all women regardless of hormonal contraception to minimize treatment bias.
Blood samples were collected after obtained informed consent from the subjects. The study protocol was approved by the local university ethical committee.
Study protocol
All subjects underwent a medical visit at which time clinical
data were recorded. Information about medical history, age of menarche,
acne (not scored), regularity of menstrual cycles (defined as 2535
days in length), medications with specific use of hormonal
contraception, and antiandrogenic therapy was collected in a
standardized questionnaire. Clinical evaluation of hirsutism has not
been assessed. Serum
4-androstenedione
(
4-A), dehydroepiandrosterone sulfate (DHEAS),
testosterone, and SHBP were measured in the IUGR-born (n = 120)
and control (n = 136) women who did not receive antiandrogenic
therapy. Biological hyperandrogenism was defined as
4-A, DHEAS, testosterone, and/or free androgen
index (testosterone x 100/SHBP) > 2 SD of the
mean values observed in the eumenorrheic control women without hormonal
contraception (n = 41). Sera were collected regardless of stage of
the menstrual cycle.
All subjects underwent during the same visit a 75-g OGTT, with plasma glucose and insulin measured at 0, 30, and 120 min after a glucose load. Fasting plasma triglycerides, cholesterol, and high density lipoprotein (HDL) cholesterol were also measured.
Analytical methods
All serum samples were stored at -20 C until assayed. Serum
4-A, DHEAS, and testosterone concentrations
were measured using RIAs (Immunotech, Marseilles, France).
SHBP was measured with a specific RIA
(I125-SBP-COATRIA, Biomérieux, Marcy
lEtoile, France). Serum insulin concentrations were measured using a
two-site immunoassay (ERIA Diagnostics Pasteur, France).
Cross-reactivity with proinsulin and derived metabolites was less than
1%. Assay sensitivity was 1.3 pmol/L. Glucose, cholesterol, HDL
cholesterol, and triglycerides were measured using enzymatic
methods.
Statistical analysis
All data were entered and analyzed using the StatView 4.5 software (Abacus Concepts, Berkeley, CA). Results are expressed as the mean ± SD for the continuous variable and as a percentage for the category variables.
Differences between the IUGR and control groups were tested using the
2 test for the category variables and
Students t test for the continuous variables. Insulin,
testosterone, SHBP, and FAI were log transformed before statistical
analyses.
An independent effect of group (IUGR vs. control) on serum androgen concentrations after adjustment for hormonal contraception was tested using an ANOVA. Additionally, a statistical interaction between groups and hormonal contraception was tested at the level of each serum androgen concentration by adding a term groupxhormonal contraception in the model.
Correlations between fasting insulin and SHBP, testosterone,
4-A, and DHEAS concentrations were tested
using linear regression models in women who did not receive hormonal
contraception only. P
0.05 was considered
statistically significant.
| Results |
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Clinical characteristics are summarized in Table 1
. Mean age did not significantly differ
between the IUGR and control groups. As previously reported, mean body
weight and height were significantly lower in the IUGR-born women (4).
Menarche occurred at a similar age in IUGR-born women and controls. All
women were studied at least 2.5 yr after menarche. Obesity,
oligomenorrhea, and acne are common features of functional ovarian
hyperandrogenism. In the present study, we did not observe any
significant differences between the IUGR and control groups for mean
body mass index, waist to hip ratio, prevalence of irregular menses, or
evidence of acne. Hormonal contraception in terms of frequency and
medication, including antiandrogen therapy, did not significantly
differ between the IUGR and control groups.
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As previously reported, all women had normal glucose tolerance. Mean blood glucose excursion, under OGTT, was higher in the IUGR-born women than in the controls, and the differences in mean plasma glucose values were significant at fasting and at 30 min [85 ± 6 vs. 83 ± 6 mg/dL (P = 0.05) and 135 ± 35 vs. 128 ± 33 mg/dL (P = 0.03), respectively]. At any time point, serum insulin concentrations under OGTT were significantly higher in IUGR-born women [fasting, 6.3 ± 4.3 vs. 5.0 ± 2.1 µIU/mL (P = 0.001); +30 min, 70.0 ± 45.0 vs. 53.3 ± 31.5 µIU/mL (P = 0.0004); +120 min, 45.7 ± 39.9 vs. 33.9 ± 20.5 µIU/mL (P = 0.003)]. The mean fasting insulin to glucose ratio, taken as a surrogate of insulin resistance, was significantly higher in women born with IUGR (7.4 ± 4.8 vs. 6.0 ± 2.6; P = 0.004). The serum lipid profile (fasting triglycerides, total cholesterol, and HDL cholesterol concentrations) did not significantly differ between the IUGR and control groups (data not shown).
Serum androgen concentrations
After adjustment for hormonal contraception, being born with IUGR
had no independent effect on
4-A
(P = 0.59), DHEAS (P = 0.35),
testosterone (P = 0.94), SHBP (P =
0.55), or the free androgen index (P = 0.63). As
expected, hormonal contraception significantly reduced
4-A (P < 0.0001), DHEAS
(P < 0.0001), testosterone (P <
0.0001), and the free androgen index (P < 0.0001) and
significantly increased SHBP (P < 0.0001). We did not
observe any significant interaction between the group variable (IUGR
vs. control) and hormonal contraception in our study
population.
As hormonal contraception had significant effects on serum androgen
concentrations, the subsequent analyses were restricted to women who
were not receiving hormonal contraception. As expected, we did not
observe any significant difference between the two groups for
4-A (2.26 ± 0.68 vs.
2.24 ± 0.55 ng/mL; P = 0.76), DHEAS (2294 ±
1117 vs. 2489 ± 1235 ng/mL; P = 0.24),
testosterone (0.82 ± 0.85 vs. 0.70 + 0.26 ng/mL;
P = 0.80; Fig. 1
), or the
free androgen index (2.47 ± 2.15 vs. 2.30 ±
2.80; P = 0.37). Serum SHBP concentrations were
slightly lower in IUGR-born women than in controls. This difference did
not, however, reach statistical significance (45.5 ± 28.2
vs. 53.1 ± 30.3 nmol/L; P = 0.27; Fig. 1
). In both IUGR and control groups, SHBP correlated negatively with
fasting insulin (r = -0.23; P = 0.03 and r =
-0.26; P = 0.05, respectively; Fig. 2
). In contrast, no significant
correlation was observed between fasting insulin and testosterone
(r = 0.07; P = 0.58 and r = 0.02;
P = 0.87),
4-A (r = 0.08;
P = 0.55 and r = 0.10; P = 0.46),
or DHEAS (r = 0.09; P = 0.51 and r = 0.20;
P = 0.19). Biological hyperandrogenism (more than +2
SD of the references values, as described in
Materials and Methods) was defined as an
4-A level greater than 3.58 ng/mL, a DHEAS
level greater than 5149 ng/mL, a testosterone level more than 1.21
ng/mL, and/or a free androgen index greater than 6.2. It was observed
in 8 of 67 (11.9%) IUGR-born women and 8 of 64 (12.5%) control women
(P = 0.81). Four IUGR-born women vs. 2
control women demonstrated 2 or more serum androgen concentrations more
than +2 SD of the references values. This
difference was not statistically significant (P =
0.40).
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| Discussion |
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Our data are not in agreement with the previous observations by Ibañez et al., who reported an association between a low birth weight and a precocious pubarche with subsequent FOH and hyperinsulinemia (3). The population studied by these researchers was selected on puberty maturation criteria, whereas our population was selected on birth data. The different selection criteria used in the two studies might explain the discrepancies found between these studies, and we believe that selection on birth data is more appropriate for studying the long term consequences of reduced fetal growth. We conclude, therefore, that in our study being born with IUGR does not appear to favor hyperandrogenism in adulthood. This conclusion is consistent with the lack of relationship between a low birth weight and the later development of polycystic ovaries observed in a cohort of 42-yr-old women (14).
The long term metabolic consequences of reduced fetal growth are well documented. In adulthood, low birth weight is known to be associated with increased type 2 diabetes, impaired glucose tolerance, and insulin resistance syndrome (15, 16, 17, 18). In our study population IUGR-born women were hyperinsulinemic compared with controls at 20 yr of age (4). It has been demonstrated that insulin increases ovarian androgen production in vitro (9, 10). In polycystic ovary syndrome serum insulin concentrations have been shown to be closely correlated to serum androgen concentrations (19, 20, 21). Likewise, insulin is involved in androgen metabolism by decreasing SHBP and thus increasing free androgen concentrations. This relationship has been well documented in several populations of normal, insulin-resistant, and type 2 diabetic subjects (11, 12, 22, 23, 24) and suggests a physiological regulation of serum SHBP concentrations by insulin. In our study population, SHBP concentrations were negatively correlated with fasting insulin concentrations in IUGR-born and control groups. This inhibitory effect of insulin on SHBP is not sufficient to favor hyperandrogenism in the hyperinsulinemic IUGR-born women of our study. These data suggest that hyperandrogenism associated with hyperinsulinemia and insulin resistance, which is observed under special conditions, such as polycystic ovary syndrome or other forms of FOH (1, 2, 6, 7, 8, 19, 20, 21), results from a complex pathological mechanism, probably independent of fetal nutritional status itself.
As we have no detailed information about the onset of puberty in our study population, we could not exclude any association between precocious pubarche and low birth weight. Previous reports about increased adrenal androgens in children born small for gestational age is consistent with such an association (25, 26, 27). Clark et al. hypothesized that the raised adrenal androgen concentrations might reflect an earlier adrenarche or a change in hypothalamo-pituitary-adrenal axis function (25). However, Dahlgren et al. reported that the negative correlation between DHEAS and birth weight he observed in young children disappears after 9 yr of age (27). This study, rather, supports the hypothesis of an earlier onset of adrenarche associated with reduced fetal growth. However, if IUGR favors precocious adrenarche, it does not necessary predispose to the subsequent development of FOH. Further explorations are required to understand whether fetal undernutrition might influence the outcome of puberty during childhood.
In conclusion, hyperinsulinemia observed in young women born with IUGR is not associated with clinical and/or biological hyperandrogenism. Consequently, our results do not support the hypothesis of a common in utero programming of functional ovarian hyperandrogenism and hyperinsulinemia.
Received May 4, 1999.
Revised June 9, 1999.
Accepted July 22, 1999.
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