BLOOD SPOT FOLLICLE-STIMULATING-HORMONE DURING EARLY POSTNATAL LIFE IN NORMAL GIRLS AND TURNERS-SYNDROME

Although FSH has previously been found to be elevated during infancy i n agonadal subjects, it is not known whether perinatal FSH levels are also increased. Neonatal blood spot FSH levels were studied retrospect ively in nine full term girls born with Turner's syndrome and compared with presumably normal full term girls born the same week. FSH was me asured using a highly specific immunoradiometric assay adapted to bloo d spots collected at the time of systematic neonatal screening. On day 5-6 after birth, FSH was undetectable (<1 IU/L) or low (1-4.4 IU/L) i n normal girls. Among the nine patients with Turner's syndrome, five h ad FSH levels below 3 IU/L, and four showed slightly elevated levels, ranging from 4.3-10.9 IU/L. These differences in FSH secretion were no t related to differences in karyotype. Among five patients studied lon gitudinally during the first 6 weeks of life, three showed increases i n FSH levels to 14.9-15.9 IU/L during the second week of life. However , this increase was comparable to that seen in some normal girls sampl ed on a second occasion during the first weeks after birth. One patien t with Turner's syndrome still had low FSH (2.5 IU/L) on day 23, but s howed some increase to 8.5 IU/L on day 30. We conclude that 1) in Turn er patients, perinatal changes in FSH secretion are similar to those i n normal girls, although there is already a lack of feedback control b y gonadal hormones on the hypothalamo-pituitary axis; and 2) the FSH a ssay cannot be used fdr neonatal screening of Turner's syndrome.