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Biological assessment of abnormal genitalia is based on an ordered sequence of endocrine and genetic investigations that are predicated on knowledge obtained from a suitable history and detailed examination of the external genital anatomy. Investigations are particularly relevant in 46,XY DSD where the diagnostic yield is less successful than in the 46,XX counterpart. Advantage should be taken of spontaneous activity of the pituitary-gonadal axis in early infancy rendering measurements of gonadotrophins and sex steroids by sensitive, validated assays key to assessing testicular function. Allied measurement of serum anti-Mullerian hormone completes a comprehensive testis profile of Leydig and Sertoli cell function. Genetic assessment is dominated by analysis of a plethora of genes that attempts to delineate a cause for gonadal dysgenesis. In essence, this is successful in up to 20% of cases from analysis of SRY and SF1 (NR5A1) genes. In contrast, gene mutation analysis is highly successful in 46,XY DSD due to defects in androgen synthesis or action. The era of next generation sequencing is increasingly being applied to investigate complex medical conditions of unknown cause, including DSD. The challenge for health professionals will lie in integrating vast amounts of genetic information with phenotypes and counselling families appropriately. How tissues respond to hormones is apposite to assessing the range of genital phenotypes that characterise DSD, particularly for syndromes associated with androgen resistance. In vitro methods are available to undertake quantitative and qualitative analysis of hormone action. The in vivo equivalent is some assessment of the degree of under-masculinisation in the male, such as an external masculinisation score, and measurement of the ano-genital distance. This anthropometric marker is effectively a postnatal readout of the effects of prenatal androgens acting during the masculinisation programming window. For investigation of the newborn with abnormal genitalia, a pragmatic approach can be taken to guide the clinician using appropriate algorithms.

Abnormal sexual development invariably manifests at birth, usually in the form of ambiguity of the external genitalia. It is estimated that 1 in 4500 live births may have a genital abnormality which is so abnormal that a decision about sex may be impossible at birth. In such cases the paediatrician will be under great pressure to respond to parental anxiety. However, it is important to undertake appropriate investigations in order to try to reach a diagnosis, and also to make, in concert with relevant professionals and the family, an early decision about the sex of rearing. Although it is beneficial that registration of the birth can be delayed in such circumstances, in some countries such as the United Kingdom, most parents will probably find it unacceptable if the sex of rearing of the newborn child was delayed for more than a fortnight. Management of ambiguous genitalia in the newborn is, therefore, a medical emergency requiring skilled handling and a sensitive approach with a reasonable knowledge about possible underlying pathology.

In Europe young patients with Graves’ disease are usually treated with antithyroid drugs initially, then if hyperthyroidism recurs after a prolonged course of such medication, they are offered definitive treatment by subtotal or total thyroidectomy. Neither of these forms of treatment is free from problems. Impressed with the simplicity and safety record of radioiodine therapy, we have treated 8 young patients with radioiodine. The patients all presented with typical Graves’ disease and relapsed after 18–24 months of treatment with antithyroid drugs. They were then given the option of a further course of antithyroid medication or definitive treatment with radioiodine or surgery. Those who opted for radioiodine were treated with 131iodine in a dose of 300 MBq with the intention of ablating the thyroid. Antithyroid medication was resumed for 4–6 months and then withdrawn. Four patients became hypothyroid after a single dose of radioiodine but 4 needed a second dose. All became hypothyroid within 2 years. No adverse effects were observed, in particular no patient showed any deterioration in their eye disease. Radioiodine offers a simple, effective and inexpensive method of treatment for Graves’ disease in young patients. There are no immediate adverse effects and, although some theoretical concerns remain, to date the long-term safety record of thyroid ablation is excellent and the potential risks seem to us to be outweighed by the advantages. Even when a moderately high initial dose of radioiodine is used, a second dose may be needed.

Congenital adrenal hyperplasia (CAH) results from enzymatic defects in the pathways of adrenal steroidogenesis, with over 90% of cases being due to 21-hydroxylase deficiency caused by autosomal recessive mutations in the CYP21 gene. Classical presentation—this is in the neonatal period with ambiguous genitalia/virilization of a female infant, with phenotype traditionally subdivided according to the presence (75%) or absence of salt wasting, which in affected males is the sole manifestation (and can, if unrecognized, be life-threatening). Delayed presentations can occur, manifest in women as hirsutism, oligomenorrhoea, and infertility and in men as infertility or testicular adrenal rest tumours....

Human sex development follows an orderly sequence of embryological events coordinated by a cascade of gene expression and hormone production in a time- and concentration-dependent manner. Underpinning the entire process of fetal sex development is the simple mantra: sex chromosomes (XX or XY) dictate the gonadotype (ovary or testis), which then dictates the somatotype (female or male phenotype)....

Graves’ disease is rare in childhood but occurs with increasing frequency into adolescence and young adult life. There is a strong familial predisposition but the precipitating cause is not known. Stimulation of the thyroid stimulating hormone (TSH) receptor by autoantibodies causes excessive thyroid hormone production and secretion, and diffuse enlargement of the thyroid. Other systems may be involved, notably the eyes with proptosis. In children the early symptoms of hyperthyroidism are non-specific and may be of gradual onset; unless there is an obvious goitre, a psychological or behavioural disorder is often suspected. Once considered, the diagnosis is readily confirmed biochemically by raised concentrations of circulating thyroid hormones and suppression of TSH. The aim of treatment is to restore and maintain permanent euthyroidism as safely, quickly, and conveniently as possible. Especially in young people, there is no consensus on how this is best achieved and in this annotation we shall consider the options. The symptoms of hyperthyroidism may be distressing and can be relieved promptly to a great extent by blocking the peripheral effects of the excess thyroid hormones. A β blocking agent such as propranolol, 1 mg/kg/day in divided doses, is effective and useful to tide the patient over until the disease is controlled. An antithyroid drug can be started at the same time. The thionamide drugs block the synthesis of thyroid hormones and also have ill understood immunosuppressive effects in Graves’ disease.1Carbimazole is more widely used in Europe and propylthiouracil in the United States; although their actions and side effect profiles are slightly different, in practice they are interchangeable. Carbimazole 0.5 to 1.0 mg/kg/day or propylthiouracil 5 to 10 mg/kg/day in divided doses brings the hyperthyroidism of Graves’ disease under control in four to eight weeks. If there is urgent need to cure the disease as soon …

Publisher Summary This chapter discusses the masculinizing and feminizing syndromes. Syndromes associated with masculinization or feminization feature external signs of physical sexual development, which are at variance with an individual's known biological sex. It is found that a female with an XX karyotype and internal female genitalia but who has developed clitoromegaly has become masculinized, the term virilized is usually used synonymously. The term feminization in a male is generally thought to mean the development of female secondary sexual characteristics in an otherwise normal male rather than an incomplete development of the normal external male phenotype. The most common cause of a masculinized female at birth is congenital adrenal hyperplasia. This is a group of disorders associated with a deficiency in one of the enzymes required for cortisol biosynthesis. A deficiency of 21-hydroxylase enzyme activity accounts for more than 90% of cases of congenital adrenal hyperplasia. The conversion of 17-hydroxyprogesterone to 11-deoxycortisol is diminished and under the influence of increased ACTH stimulation, the relatively inert precursor steroid 17-hydroxyprogesterone acts as a substrate for increased androstenedione production. This steroid is a weak androgen that is further converted in the liver to the active androgen, testosterone.

A detailed study involving simultaneous measurements of plasma and saliva 17OH-progesterone (17OHP), and plasma testosterone concentrations was performed at frequent intervals over a 3-year period in

The concentration of 170H-progesterone was measured in amniotic fluid samples collected from 55 mothers who had previously had a child with congenital adrenal hyperplasia due to 21-hydroxylase deficiency. In eight pregnancies the levels of 170H-progesterone were raised; the parents elected to terminate in four and examinations of the fetus confirmed the diagnosis of congenital adrenal hyperplasia. In each case, the affected sib was a salt loser. The remaining four affected pregnancies proceeded to term and each infant had salt losing 21-hydroxylase deficiency. All 47 infants predicted to be unaffected were normal at birth. However, an increased plasma concentration of 170H-progesterone was documented in a male non-salt loser at three months of age. Prenatal diagnosis of congenital adrenal hyperplasia by amniotic fluid steroid analysis is reliable only for the salt losing variant of 21-hydroxylase deficiency. Of the affected sibs in this study, 20% died during infancy in a salt losing crisis. This simple and rapid prenatal test is sufficiently reliable to predict the group of infants most at risk in early infancy.

The distribution of von Willebrand factor antigen (vWFAg) and fibronectin (Fn) in endothelial cells and in fibroblasts in culture was examined using immunohistological methods. Extracellular matrices were studied after removal of cells by mild hypotonic lysis. Co-distribution of these antigens was also examined after culture of fibroblasts in the presence of endothelial cell conditioned medium or of exogenous vWFAg. The presence of intracellular vWFAg and its association with extracellular Fn in confluent endothelial cells was confirmed. Furthermore, both antigens were detected in matrices from fibroblasts grown in the presence of human plasma and endothelial cell medium. vWFAg was not found, however, in the absence of endothelial cell conditioned medium or in experiments using human serum in place of plasma. Cross-linking of vWFAg was examined using quantitative and qualitative electrophoretic methods. Levels of vWFAg in serum from patients with severe Haemophilia A were approximately 50% of those found in the corresponding plasma. Furthermore, vWFAg was reduced to similar levels in serum from normal blood to which heparin was added. The lowest levels of vWFAg were found in the presence of sufficient heparin to totally inhibit the formation of fibrin. In contrast, levels of Fn remained unchanged in these circumstances. The results did not support the view that vWFAg was cross-linked to Fn in plasma by thrombin-activated factor XIII. In addition, immunoelectrophoresis of cultured endothelial cell products did not demonstrate cross-linking of vWFAg to Fn. The data are consistent with the concept that deposition of vWFAg on the subendothelium is dependent on viable endothelial cells or on another product of these cells.

Publisher Summary This chapter explains the use of growth hormone-releasing hormone (GHRH or GRF) and corticotrophin-releasing factor (CRF) hormones in diagnostic tests. It has been found that CRF has a little practical application in the investigation of pediatric endocrine disease. The chapter also explains that antidiuretic hormone (ADH) is synthesized in the hypothalamus, transported along axons in the neurohypophyseal tract, and stored in the posterior pituitary gland. As ADH secretion is controlled mainly by plasma osmolality, water deprivation is the main stimulus for testing adequate ADH secretion. Secretion from the posterior pituitary is regulated mainly by changes in osmolality of the extracellular fluid. ADH release is assessed by indirect methods. Tests of growth hormone (GH) secretion are classified into physiological and pharmacological. The former takes advantage of some normal physiological variables, such as exercise and sleep where GH secretion is enhanced.

This chapter describes the investigations required to determine the causes of hypo- or hypercalcaemia associated with either parathyroid disease or disordered vitamin D metabolism. It is important to exclude a non-endocrine cause for abnormal calcium metabolism, such as chronic renal failure. Hypocalcaemia is the more frequent problem in children. Neonatal hypocalcaemia is a relatively common transient condition and is not because of a persistent endocrinopathy. Occasionally, neonatal hypocalcaemia is the result of maternal hyperparathyroidism; therefore, it is necessary to check the plasma calcium level in the mother. The total plasma calcium must be determined on more than one occasion with the patient fasted before more detailed and complex investigations for the cause of hypocalcaemia are started. If possible, the blood sample should be collected with the least amount of venous stasis. Hypercalcaemia is uncommon in children. Confirmation of hypercalcaemia is essential before embarking on extensive investigations. An elevated fasting plasma calcium should be confirmed on three separate determinations. The principal dynamic test for the investigation of hypocalcaemia is an assessment of the renal response to exogenous parathyroid hormone (PTH). The results determine the cause of hypoparathyroidism.

Glucocorticoid-related changes in 17OH-progesterone (17P) concentrations were studied in 13 patients receiving treatment for 21-hydroxylase deficiency congenital adrenal hyperplasia (CAH). Blood spot and saliva 17P levels were elevated, with or without loss of diurnal rhythm, within 24 h of stopping maintenance glucocorticoid therapy. A single dose of dexamethasone (0.01 mg/kg) given either intravenously or orally at 09.00 h resulted in rapid onset of complete pituitary-adrenal suppression characterised by a prompt and exponential fall in 17P levels (first-order elimination half-life, mean 2.87 h, range 1.98-3.98 h). Concentrations of 17P remained low throughout the day until the onset of an abrupt nocturnal rise, which occurred between 24.00 and 05.00 h. There were individual differences in both the rate of fall and the timing of the nocturnal rise in 17P levels which may partly explain the need to vary individual steroid requirements in the treatment of CAH.

A comparative study of adrenal morphology between normal fetuses and those with anencephaly or congenital adrenal hyperplasia (CAH) was performed in order to examine the hypothesis that fetal adrenal mass and structure are adrenocorticotrophin (ACTH)-dependent throughout gestation. Combined adrenal weight in 102 normal fetuses was used to establish a reference range for the gestational ages of 15–27 weeks. During this period, mean adrenal weight showed a 6-fold linear increase. In 38 anencephalic fetuses of similar gestation age, adrenal weight was below the normal range and did not show a rise. Three fetuses with CAH (18, 22 and 30 weeks gestation) had adrenal weights considerably above the normal range. Adrenal cortical thickness was significantly increased in CAH fetuses, largely as a consequence of cell hypertrophy, whereas decreased cortical thickness in the anencephalic group represented cellular hypoplasia. Conspicuous secretory granules in the cytoplasm was the electron-micrographic feature of the adrenal gland in the 22-week fetus with CAH. These observations are consistent with close dependency of fetal adrenal growth and development upon fetal pituitary function from an early age, mediated primarily through ACTH.

Nuclear thyroid hormone receptors of patients with the syndrome of resistance to thyroid hormone were investigated in cell lines from seven patients in four affected families and compared to results from six normals. Fibroblasts cultured from skin biopsies were used. When binding affinity and capacity for l -triiodothyronine (T 3 ) were examined by incubating whole cells or isolated nuclei, no significant differences were found. The amount of receptor released during the incubation of nuclei (9.3% to 19.0% of total nuclear receptors) was also within the normal range in these patients. When T 3 binding assays were performed on 0.3 mol/L KCl extracted receptor, a significant decrease in binding capacity (MBC) without a difference in binding affinity (Ka) was observed in four patients and a lower Ka with normal MBC was found in two patients. Recovery of receptors in saline extracts, from patients' fibroblasts showing a low MBC, was low in comparison to normals. Lability of salt extracted receptors at 38 °C was normal and salt extractability of T 3 occupied receptors, examined by incubation of [ 125 I]-T 3 labeled nuclei with various concentrations of KCl, was only slightly decreased. This lower salt extractability of receptors was insufficient to account for the low MBC obtained by Scatchard analysis of T 3 binding to nuclear extracts. Gel filtration and density gradient sedimentation of salt-extracted receptors showed Stokes radius of 34 A, and sedimentation coefficient of 3.4 S in all patients and normals. From these values, molecular weight of 49,000 and total frictional ratio ( f fo ) of 1.4 were calculated for nuclear receptors from patients and normals, suggesting a somewhat asymmetrical shape of receptors. Density gradient sedimentation patterns of micrococcal nuclease digested receptors, in which receptors were associated with 6.5, 12.5, and 17 S chromatin components, was also indistinguishable from normals. We conclude that in most patients with generalized thyroid hormone resistance, abnormalities of receptor function are evident after salt extraction of fibroblast nuclear receptors, but that the receptors have normal shape and thermolability. These abnormalities were consistent within but heterogeneous between sibships, suggesting heterogeneity of hereditary abnormalities in nuclear receptors in this disorder.

Publisher Summary This chapter discusses the tests available to assess thyroid function. Functionally, it can be divided into: (1) thyroid profile, which defines a state of euthyroidism, hypothyroidism, or hyperthyroidism; (2) definitive tests, which establishes etiology of thyroid disease. Thyroid profile measures thyroxine (T4), tri-iodothyronine (T3), free thyroxine and free tri-iodothyronine, reverse tri-iodothyronine, and thyroxine binding globulin. In definitive tests, thyroid-stimulating immunoglobulins and thyroid auto-antibodies are measured using different technology, such as thyroid stimulation test, radioactive isotopes, and thyroid ultrasound. Hyperthyroidism is uncommon in childhood, particularly in boys. The clinical diagnosis is confirmed by the presence of increased thyroid hormone concentrations and undetectable basal serum thyroid stimulating hormone (TSH). With the improved sensitivity TSH assays, it is possible to differentiate between normal and hyperthyroid states using basal serum TSH measurements. The chapter also discusses the protocol for the investigation of congenital hypothyroidism with the help of various case illustrations.

Publisher Summary This chapter discusses the clinical evaluation of gonadal function. It discusses specific tests of testicular or gonadal function. Testicular function is under the control of gonadotropin-releasing hormone (GnRH) via pituitary luteinizing hormone (LH) and follicle-stimulating hormone (FSH) secretion. Testosterone biosynthesis by the Leydig cells of the testis proceeds via a sequence of enzymatic steps under the control of LH secretion. There is a negative feedback of testosterone on LH secretion both directly at the pituitary and indirectly at the hypothaiamic level. The feedback relationship is developed in early infancy. The chapter also discusses the diagnosis of bilateral testicular torsion primary hypogonadism, bilateral cryptorchidism, isolated micropenis, pubertal gynaecomastia, and complete androgen insensitivity syndrome androgen-receptor negative. It also discusses the diagnosis of partial androgen insensitivity syndrome androgen-receptor positive, ambiguous genitalia mixed gonadal dysgenesis, delayed puberty (female) radiation-induced primary ovarian failure, acute myeloid leukaemia secondary lymphoma,, premature thelarche, and idiopathic hirsutism.

This chapter discusses the disorders of the endocrine pancreas that produces either hyperglycaemia or hypoglycaemia in children. There has been an explosion in discovery and measurement recently of gut-related hormones. Conditions associated with increased production of these hormones, generally termed apudomas, are now being characterized. However, these are uncommon in children because they usually present with symptoms and signs referable to the gastrointestinal tract. In all age groups, apart from the neonatal period, hypoglycaemia is defined as blood glucose less than 2-2 mmol/l (40 mg/dl). Early neonatal hypoglycaemia, which is transient, usually occurs in low-birth-weight infants. The chapter discusses the diagnosis of persistent neonatal hypoglycaemia nesidioblastosis, insulin-dependent diabetes mellitus, and severe diabetic ketoacidosis hyperlipaemia.

This chapter presents potential application of the techniques of molecular biology to the investigation of endocrine diseases in children. Several inherited endocrine disorders are recognized in childhood, particularly involving adrenal, thyroid, and gonadal function. A vast array of cDNA probes is now available to study the human genome and several endocrine disorders can be investigated by nucleic acid hybridization analysis. The clinical investigator is the most important initial cog in the long chain of events that starts with DNA extraction and finishes typically with the procedure of southern blotting and autoradiography. It is important that the clinician is competent to know (a) which samples to collect for DNA analysis and (b) which endocrine disorders can be investigated by recombinant DNA technology.

This chapter discusses general principles for appropriate endocrine tests. Tests of endocrine function in children usually require serial blood samples and/or 24-h urine collections following the administration of agents, which stimulate or suppress hormone levels. In general, random blood samples for hormone measurements in children are unhelpful. The procedures can be unpleasant and may produce side effects. An individual should undergo appropriate testing only after detailed history and physical examination has suggested the presence of a specific endocrine disorder. For example, a short child should be examined for growth hormone (GH) deficiency only after the clinician is satisfied that the cause is not because of or associated with low birth weight, parental size, adverse social factors, and general systemic disease. An accurate record of decreased growth velocity determined preferably over one year should be available before arranging endocrine tests. The suitably constructed growth chart is assuming more importance as the benchmark; the often bewildering array of tests of GH secretion should only serve to supplement the anthropometric information.