Nc. Nathwani et al., GONADOTROPIN PULSATILITY IN GIRLS WITH THE TURNER-SYNDROME - MODULATION BY EXOGENOUS SEX STEROIDS, Clinical endocrinology, 49(1), 1998, pp. 107-113
OBJECTIVES The endocrine manisfestation of puberty, nocturnal pulsatil
e secretion of gonadotrophins precedes the physical manifestations by
2 years. Whether gonadal steroids and inhibin have a role to play in t
he regulation of pulsatile gonadotrophin release is unclear, The agona
dal model, girls with Turner's syndrome (TS), has been used to determi
ne the role of the hypothalamic pulse generator in the ontogeny of gon
adotrophin secretion in man, We evaluated the ontogeny of gonadotrophi
n secretion in TS girls with respect to amplitude and frequency and co
mpared these results to those obtained in a group of normal girls. The
effects of treatment with ethinyloestradiol (EE,) or oxandrolone (OX)
on parameters of gonadotrophin secretion were also evaluated, PATIENT
S We studied 32 girls with TS, aged 4.3-1.2 4 years. All were prepuber
tal at the start of the study and longterm follow up revealed that non
e entered spontaneous puberty. The pulse amplitude and frequency was e
valuated and compared to the results obtained in 23 normal girls, aged
4.9-12.8 years who acted as controls, MEASUREMENTS Samples were taken
at 20 minute intervals for 24 h for the measurement of serum concentr
ations of luteinising (LH) and follicle stimulating (FSH) hormones, Th
e girls were than randomized to receive EE2 or OX and were then re-adm
itted 6 months into the course of the treatment for a repeat 24h serum
profile of LH and FSH levels. RESULTS The girls with TS showed a clea
rly defined dominant pulse periodicity of 180 min and that in the norm
al cohort was 160-220 min. The girls with TS had an increased oscillat
ory activity between 120 and 260min compared to the normal, Mean 24h s
erum gonadotrophin concentration in TS girls was always higher than in
the normal cohort, The inflection points of the fitted polynominal re
gression equation relating sex hormone concentration with age was simi
lar for the two groups, EE2 lead to a significant change in pulse peri
odicity in TS girls but OX had no significant effect on the pulse peri
odicity. CONCLUSION These results demonstrate that girls with Turner s
yndrome have gonadotrophin pulse periodicity in the prepubertal years
similar to those of normal girls, The oscillatory activity was much gr
eater in girls with Turner syndrome at all ages in the prepubertal yea
rs, suggesting a role for the ovary in modulating gonadotrophin secret
ion in the prepubertal years, Our data confirm that in girls with Turn
er syndrome the normal pattern of gonadotrophin secretion evolving wit
h time is preserved.