Thyroid Function in the Fetus and Newborn

Fisher, Delbert A.

doi:10.1016/s0025-7125(16)31960-5

Cited by 46 publications

(49 citation statements)

References 35 publications

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“…However, estradiol and estrone in the fetal circulation originate mainly from precursors secreted by the maternal adrenal cortex (60,61), therefore, the circulating levels of these two steroids in the fetus should not be greatly affected by anencephaly. This was recently demonstrated in one anencephalic infant in whom the high plasma concentrations of unconjugated 17 f-estradiol and estrone in umbilical cord blood were in the normal range (62 (21)(22)(23)(24). In the case of hGH., although a GH release inhibiting factor or somatostatin has been described (63), the very low GH plasma levels usually found in anencephalic infants suggest that GH secretion in the fetus is primarily under the influence of a growth hormone releasing factor (GRF).…”

Section: Ontogenesis Of Human Fetal Hormones 159mentioning

confidence: 82%

The ontogenesis of human fetal hormones. III. Prolactin.

Aubert¹,

Grumbach²,

Kaplan³

1975

J. Clin. Invest.

113

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A B S T R A C T The synthesis and release of human prolactin (hPRL) in the human fetus was assessed by radioimmunoassay analysis of the content and concentration of hPRL in 82 pituitary glands and the concentration of serum hPRL in 47 fetuses of gestational age 68 days to term. Fetal hPRL exhibited parallelism with the reference standard (Lewis 203-1). hPRL was detected by 68 days of gestation (10 wk), the earliest fetal pituitary gland studied; 8 out of 33 pituitaries had a prolactin (PRL) content above 2.0 ng between 10-15 wk gestation. The mean content of PRL in the pituitary gland increased sharply from 14.8±4.6 ng at 15-19 wk to 405±142 ng at 20-24 wk and 542±204 ng at 25-29 wk gestation. By term, the mean content was 2,039± 459 (range 493-3,689) and the mean concentration 15.9±2.4 ng/mg (range 7-20). There was a significant positive correlation (P < 0.001) between the hPRL and human growth hormone (hGH) content of fetal pituitary glands; at term the hPRL/hGH ratio was 1/290. The concentration of serum hPRL between 12 and 24 wk ranged from 2.9 to 67 ng/ml, mean 19.5±2.5 ng/ml (n = 41); by 26 wk fetal serum hPRL increased sharply and attained levels of 300-500 ng/ml in late gestation. At delivery, the mean plasma concentration of hPRL was 167±+14.2 ng/ml in 36 umbilical venous specimens and 111.8±12.3 ng/ml in the matched maternal venous specimens. No correlation between serum hPRL and the pituitary content or concentration of hPRL was demonstrable in 12 matched fetal specimens.In five anencephalic infants, umbilical venous hPRL levels were between 65 and 283 ng/ml. In two anencephalic infants, thyrotropin releasing factor (TRF) (200 Ag IV) evoked a rise in serum hPRL in one patient from 43 to 156 ng/ml at 30 min, and in the other from 65 to Dr. Aubert is recipient of a grant from the Swiss National Fund for Scientific Research.

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Section: Ontogenesis Of Human Fetal Hormones 159mentioning

confidence: 82%

The ontogenesis of human fetal hormones. III. Prolactin.

Aubert¹,

Grumbach²,

Kaplan³

1975

J. Clin. Invest.

113

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“…Its chemical properties (for review see Reference 8) and variations of the plasma levels of the factor in different pathologic conditions have been the subject of several studies (e.g., 11,13,18,19,22). For newborn infants, some authors reported low values (1, 3, 7, 23), whereas others have found normal adult levels (6,14,17,21,24). However, all of these investigations were carried out with bioassays, such as differential clot solubilities, which from the quantitative point of view are of questionable reliability.…”

Section: Extractmentioning

confidence: 99%

Growth and Development of the Thyroidectomized Ovine Fetus

et al. 1974

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ExtractThyroidectomies were performed through a flank incision and uterotomy on five fetuses of 1-4-year-old Columbia and Columbia Suffolk date-bred ewes of 90-1 1 0 days gestation. The fetuses were killed 19-43 days post-thyroidectomy. Body and organ weights, limb roentgenograms, DNA, RNA, and protein concentrations of selected tissues, cerebral and cerebellar lipid concentrations, and cerebellar cerebroside fatty acid composition were measured and compared with similar measurements in control animals. In the thyroidectomized fetuses mean carcass and lung weights were significantly reduced and wool development was consistently delayed. Extremity x-rays showed a delay in the time of appearance and a decrease in the size of epiphyseal centers. The mean DNA concentration was low in muscle tissue; mean protein concentrations were reduced in cerebellum, heart, lung, thymus, and muscle tissues, while mean total lipid concentration was low in cerebral tissue; the percentage of 18-carbon fatty acids was significantly increased in cerebellar cerebrosides. These results indicate that thyroid hormone deficiency, present during the last trimester of gestation in the ovine fetus, impairs carcass and lung growth, delays bone and skin maturation, inhibits growth in cell size in heart, lung, thymus, and cerebral tissues, and delays myelination in the central nervous system (CNS). SpeculationThe present results, considered with results of other investigations of the effects of thyroid hormone deficiency in fetal and newborn mammals, indicate that hypothyroidism impairs somatic growth, delays bone growth and maturation, delays cell growth and replication in the CNS, and inhibits CNS myelination. The critical period for these effects varies in different species. In the rat this period is postnatal, whereas in the sheep it extends into the third trimester of pregnancy. During pregnancy, carcass growth, bone maturation, and lung maturation are most affected in the sheep; CNS changes are minimal. In man fetal hypothyroidism may produce some delay in bone maturation but somatic growth retardation and signs and symptoms of hypothyroidism are not usually present a t birth. Moreover, as in the sheep, any delay in CNS maturation probably is minimal in utero, since very early postnatal treatment minimizes mental retardation. Thus early diagnosis and treatment of hypothyroidism is necessary and consideration of the possibility of newborn screening would seem appropriate.19, 23). Therefore, it is possible that thyroid hormones are not necessary for normal fetal somatic growth. The effect of intrauterine hypothyroidism on CNS growth and maturation also is not entirely clear. Thus we have conducted studies of body and organ growth and thyroid hormone kinetics in the fetal sheep after thyroidectomy. The kinetic studies, described elsewhere (141, indicated that fetal serum levels of both thyroxine (T4) and triiodothyronine ( T 3 ) are unmeasurable soon after fetal thyroidectomy and that the athyrotic fetus receives minimal quantities of materna...

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“…Serum free T 3 versus gestational age. 8.0 weight of the preterm groups were significantly different (P<O·OOI) from the fullterm group.…”

Section: Methodsmentioning

confidence: 76%

Serum Free Thyroxine and Free Triiodothyronine Concentrations in Healthy Fullterm, Preterm and Sick Preterm Neonates

John

Bamforth

1987

Ann Clin Biochem

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SUMMARY. There are few data available on free thyroid hormone concentrations in the early neonatal period. With the widespread application of screening procedures for detecting congenital hypothyroidism there is a need for reference ranges in neonates. In this study we have evaluated thyroid function in healthy fullterm and preterm neonates, and sick neonates all within one to to days postnatal age. Our data indicates that free thyroxine but not free triiodothyronine is higher in fullterm neonates than the adult reference range and that both free thyroid hormone concentrations are reduced in healthy and sick preterm neonates as compared to fullterm neonates. Assessment of thyroid function in the early neonatal period needs to take into account these changes particularly in preterm and sick preterm neonates.The sequence of events leading to the development of the thyroid and the control and secretion of the thyroid hormones in the fetus has been well reviewed by Fisher. I At birth, an acute release of thyrotrophin (TSH) occurs which stimulates an increase of both thyroxine (T 4 ) and triiodothyronine (T 3 ) concentrations in serum. The peak TSH concentration occurs within an hour of birth but rapidly declines during the first 24 h with a slower decrease over the following two days. Serum T 4 and free T 4 concentration after peaking at 24 h then slowly decrease during the first few weeks of Iife. • 3Essentially similar changes occur in serum T3 and free T3 concentrations. In premature neonates without serious illness, both T 4 and TSH follow the same pattern as fullterm neonates although at a lower level.Although there are published indices of thyroid function in healthy babies and children,": 5. 6. 7 in premature babies using cord blood ll • 9 • 10 and serum, II. 12. 13 and in prematures with respiratory distress syndrome;" information on free thyroid hormone concentrations measured by the newer direct technique in the early neonatal period is more limited. With the widespread adoption of screening proceCorrespondence: Rhys John. dures for congenital hypothyroidism using the filter paper blood sample collected between three and seven days postnatally, there has been an increased need to evaluate thyroid function in neonates. In most instances, using TSH as the screening assay, the diagnosis of neonatal hypothyroidism is easily made but in a proportion who show only moderately increased TSH concentrations, full thyroid function tests may need to be done to determine whether any thyroid dysfunction is present. These moderately increased TSH concentrations are usually only transient elevations and are seen particularly in preterm infants or in acutely ill infants. 15 The aim of this study was to define normal serum free thyroid hormone concentrations in fullterm, preterm and sick preterm neonates. Materials and methodsA total of 104 neonates, with ages ranging from one to 10 days were studied. Five were delivered with the aid of forceps, 20 by caesarian section and the remaining were delivered vaginally. The fullter...

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Thyroid Function in the Fetus and Newborn

Cited by 46 publications

References 35 publications

The ontogenesis of human fetal hormones. III. Prolactin.

The ontogenesis of human fetal hormones. III. Prolactin.

Growth and Development of the Thyroidectomized Ovine Fetus

Serum Free Thyroxine and Free Triiodothyronine Concentrations in Healthy Fullterm, Preterm and Sick Preterm Neonates

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