Early assessment of hypothalamic-pituitary-gonadal function in patients with congenital hypothyroidism of central origin

Neonatal Hypopituitarism: Approaches to Diagnosis and Treatment

Hypopituitarism is defined as a decreased release of hypophyseal hormones, which may be caused by disease of the pituitary gland disease or hypothalamus. The clinical findings of neonatal hypopituitarism depend on the causes and on presence and extent of hormonal deficiency. Patients may be asymptomatic or may demonstrate non-specific symptoms, but may still be at risk for development of pituitary hormone deficiency over time. Patient history, physical examination, endocrinological, radiological and genetic evaluations are all important for early diagnosis and treatment. The aim of this paper was to present a review of etiological factors, clinical findings, diagnosis and treatment approaches in neonatal hypopituitarism.

Childhood growth of females with Kallmann syndrome and FGFR1 mutations

OBJECTIVE

In search of phenotypic cues that would allow early detection of Kallmann syndrome (KS), we evaluated the paediatric phenotypes in a series of females with KS.

DESIGN, PATIENTS AND MEASUREMENTS

In this retrospective cohort study, we investigated childhood growth in six females with KS due to mutations in FGFR1 and evaluated their reproductive phenotypes later in life.

RESULTS

While growth during early infancy and childhood was within normal limits, a decreasing trend in height SDS already from mid-childhood occurred in most patients. The lowest height SDS (mean, -1·2 SDS) occurred between 14 and 15 years of age, before the start of hormone replacement therapy. As adults, these women required assisted reproductive techniques for fertility. One of the probands passed on her G48S mutation to her son, who showed normal reproductive hormone levels during the minipuberty of infancy.

CONCLUSIONS

Early diagnosis of female KS remains a challenge as early phenotypic signs, apart from anosmia, are scarce. Females with KS exhibit a slight reduction in growth rate during mid-childhood, but normal growth rate during the minipuberty of infancy, despite congenital lack of ovarian oestrogen. Women harbouring FGFR1 mutations will have 50% chance of passing on the gene defect to their offspring. We recommend genetic counselling to all females with KS to be carried out as a part of family planning.

A comprehensive review of genetics and genetic testing in azoospermia

Azoospermia due to obstructive and non-obstructive mechanisms is a common manifestation of male infertility accounting for 10-15% of such cases. Known genetic factors are responsible for approximately 1/3 of cases of azoospermia. Nonetheless, at least 40% of cases are currently categorized as idiopathic and may be linked to unknown genetic abnormalities. It is recommended that various genetic screening tests are performed in azoospermic men, given that their results may play vital role in not only identifying the etiology but also in preventing the iatrogenic transmission of genetic defects to offspring via advanced assisted conception techniques. In the present review, we examine the current genetic information associated with azoospermia based on results from search engines, such as PUBMED, OVID, SCIENCE DIRECT and SCOPUS. We also present a critical appraisal of use of genetic testing in this subset of infertile patients.

Congenital hypothyroidism: etiology

The etiology of congenital hypothyroidism (CH) is important in determining its severity, prognosis, genetic counseling and clinical management.

AIMS

investigate the causes of CH and their severity using serum levels of FreeT4 and TSH.

PATIENTS AND METHODS

243 neonates with CH (61% were girls) diagnosed by the Neonatal Screening Program of Minas Gerais between 1996 and 2003. The thyroid function was assessed through serum FreeT4 and TSH by chemilumiscence. CH etiology was evaluated by ultrasonography, scintigraphy, potassium perchlorate discharge test and serum thyroglobulin levels.

RESULTS

Out of 243 patients, dysgenesis was found in 114 (47%): 3.3% had athyreosis; 0.4% eutopic dysgenetic gland due to maternal use of 131I; 22% ectopic glands (8.6% an isolated ectopic gland and 13% also an eutopic dysgenetic thyroid); 9% eutopic dysgenesis, 8.6% hypoplasia and 3.7% hemiagenesis. Thyroid in situ was found in 129 (52%): 23.5% had iodide organification defect; 3.7% thyroglobulin synthesis defect; 6.2% other 0.4% dyshomonogenesis; iodide transport defect; 1.2% transient CH and 18% a normal gland. Patients with dysgenesis had a more severe CH than those with thyroid in situ (TSH 248.08 vs. 18.17 microIU/mL and FT4 0.32 vs. 0.95 ng/dL, p < 0.001).

CONCLUSIONS

Some cases had more complex dysgenesis, presenting ectopia associated to a dysgenetic eutopic gland. The ultrasound was the best tool to detect the dysgenetic tissue, but the scintigraphy was the most effective in identifying the functioning tissue. The thyroid hormone synthesis defects were found more frequently than expected, but in some cases they could not be defined.

Genetic forms of hypopituitarism and their manifestation in the neonatal period

The anterior pituitary gland is a central regulator of growth, reproduction and homeostasis. The development of the pituitary gland depends on the sequential temporal and spatial expression of transcription factors and signalling molecules. Naturally occurring and transgenic murine models have demonstrated a role for many of these molecules in the aetiology of congenital hypopituitarism. These include the transcription factors HESX1, PROP1, POU1F1, LHX3, LHX4, PITX1, PITX2, OTX2, SOX2 and SOX3. Mutations in any of the genes involved in pituitary development may result in congenital hypopituitarism, which manifests as the deficiency in one or more pituitary hormones. The phenotype can be highly variable and may consist of isolated hypopituitarism, or more complex disorders such as septo-optic dysplasia (SOD) and holoprosencephaly. Neonates with congenital hypopituitarism may present with non-specific symptoms, with or without associated developmental defects such as ocular, midline and genital abnormalities. Alternatively, they may be initially asymptomatic but at risk of developing pituitary hormone deficiencies over time. The overall incidence of mutations in known transcription factors in patients with hypopituitarism is low, indicating that many genes remain to be identified. Their characterization will further elucidate the pathogenesis of this complex condition and will shed light on normal pituitary development.

Role of corticotropin-releasing hormone testing in assessment of hypothalamic-pituitary-adrenal axis function in infants with congenital central hypothyroidism

CONTEXT

The Dutch neonatal congenital hypothyroidism (CH) screening program detects infants with CH of central origin (CH-C). These infants have a high likelihood of multiple pituitary hormone deficiencies. ACTH deficiency especially poses an additional risk for brain damage and may be fatal.

OBJECTIVE

Our objective was to evaluate different tools for assessment of the integrity of the hypothalamus-pituitary-adrenocortex (HPA) axis in young infants, aiming for a strategy for reliable and timely diagnosis.

DESIGN, SETTING

This is a Dutch nationwide prospective study (enrollment 1994-1996). Patients were included if neonatal CH screening results were indicative of CH-C and HPA axis function could be tested within 6 months of birth.

PATIENTS

Nine male and three female infants with CH-C and four infants with false-positive screening results or transient hypothyroidism were included in the study.

MAIN OUTCOME MEASURES

CRH test results, multiple cortisol plasma concentrations, and cortisol excretion in 24-h urine were measured.

RESULTS

Six (50%) of the CH-C patients had abnormal CRH test results. Three of them had discordant test results: impaired increase of plasma cortisol in response to CRH, despite substantial increase of plasma ACTH. The other three infants, with concordant impaired responses of both ACTH and cortisol to CRH, had a very low urinary cortisol excretion in comparison with the subjects with normal CRH test results.

CONCLUSIONS

The CRH test proves to be a fast and reliable tool in the assessment of HPA axis (dys)function. It enables timely diagnosis in (asymptomatic) neonates at risk for serious morbidity and mortality. The discordant response type, which has not been described before, may be an early phase of HPA axis dysfunction. Alternatively, patients with this response type may constitute a separate pathogenetic subset of HPA axis-deficient patients.

Role of the thyrotropin-releasing hormone stimulation test in diagnosis of congenital central hypothyroidism in infants

CONTEXT

A shortage of thyroid hormone during prenatal life and the first years after birth results in a spectrum of neuropsychological disorders, depending on the duration and severity of the deficiency. In the case of congenital hypothyroidism of central origin (CH-C), the majority of patients have multiple pituitary hormone deficiencies (MPHD). This condition poses an additional threat to postnatal central nervous system development, primarily on account of neuroglycopenia due to ACTH/cortisol deficiency with or without additional GH deficiency. Therefore, in CH-C, rapid diagnosis is even more urgent than in congenital hypothyroidism of thyroidal origin.

OBJECTIVE

In the assessment of hypothalamic-pituitary-thyroid function, we considered the pituitary response to iv administration of TRH (TRH test) pivotal. We evaluated the usefulness of the TRH test in a cohort of infants with neonatal congenital hypothyroidism screening results indicative of CH-C by analyzing the results within the framework of investigations of the anatomical and functional integrity of the hypothalamo-hypophyseal system.

DESIGN AND SETTING

The study was a Dutch nationwide prospective study (1994-1996). Patients were included if neonatal congenital hypothyroidism screening results were indicative of CH-C and patients could be tested within 3 months of birth.

PATIENTS

Ten male and five female infants with CH-C, detected by neonatal screening, and six infants with false-positive screening results, nonthyroidal illness, or transient hypothyroidism, were included in the study.

MAIN OUTCOME MEASURES

Results of TRH tests, within the framework of extensive endocrinological examinations and cerebral magnetic resonance imaging, were measured.

RESULTS

All patients with type 3 TSH responses to TRH had MPHD, and the majority (67%) of patients with type 2 responses had isolated TSH deficiency.

CONCLUSIONS

The TRH test has a pivotal role in the diagnosis of TSH deficiency in young infants. Abnormal TRH test results, especially a type 3 response, urge immediate assessment of integral hypothalamic-pituitary function because the majority of patients have MPHD.