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Puberty and Its Disorders in the Male

Puberty is the process through which children attain adult secondary sexual characteristics and reproductive capability. In humans, two distinct processes of sexual maturation are recognized: gonadarche and adrenarche. Gonadarche is defined as the growth and maturation of the gonads, resulting in increased sex steroid secretion (most notably testosterone in boys) and spermatogenesis. Gonadarche requires an intact hypothalamic-pituitary-gonadal (HPG) axis, and any disruption of this axis can…

Turner Syndrome

Historical background Turner syndrome (TS) is defined as a disorder caused by complete or partial absence of the second sex chromosome, with or without cell line mosaicism. This further needs to be associated with one or more characteristic physical features in a phenotypic female, such as short stature or primary ovarian insufficiency. The eponym comes from a study published in 1938 by Henry Turner, who described…

Puberty in the Female and Its Disorders

Puberty is the stage of development during which secondary sexual characteristics appear and there is a transition from the sexually immature to the sexually mature stage. Adolescence is widely used as a generally synonymous term for puberty, but it is often used to convey an added cultural connotation as a psychosocial coming of age. By the mid-1960s a general concept of the major factors involved in…

Pheochromocytoma/Paraganglioma, Medullary Thyroid Carcinoma, and Hereditary Endocrine Neoplasia Syndromes

Introduction Endocrine neoplasms comprise a variety of benign and malignant tumors that arise from the endocrine glands or other neuroendocrine tissues, such as the paraganglia. Most childhood endocrine tumors, typified by papillary thyroid carcinoma, are sporadic and not attributable to an identifiable germline mutation whereas others, epitomized by catecholamine-producing tumors ( Table 15.1 ) and medullary thyroid carcinoma (MTC), are familial and occur within the context…

The Adrenal Cortex and Its Disorders

History, embryology, and anatomy The adrenal cortex produces three principal categories of steroid hormones that regulate a wide variety of physiologic processes from fetal to adult life. Mineralocorticoids, principally aldosterone, regulate renal retention of sodium and thus profoundly influence electrolyte balance, intravascular volume, and blood pressure. Glucocorticoids, principally cortisol, are named for their carbohydrate-mobilizing activity, but they are ubiquitous physiologic regulators, influencing a wide variety of…

Thyroid Disorders in Children and Adolescents

Introduction Thyroid disease can present with overt symptoms, insidiously, or with isolated thyromegaly. Thyroid disease in children can encompass isolated biochemical abnormalities that have little or no physiological consequence, or with overt clinical symptoms. Clinically, hypothyroidism occurs more commonly than hyperthyroidism. Thyroid nodules and masses occur much less commonly than functional disorders but can portend the presence of thyroid cancer. Box 13.1 provides a classification of…

Disorders of the Posterior Pituitary

Introduction Maintenance of the tonicity of extracellular fluids within a very narrow range is crucial for proper cell function. Extracellular osmolality regulates cell shape, as well as intracellular concentrations of ions and other osmolytes. Furthermore, proper extracellular ionic concentrations are necessary for the correct function of ion channels, action potentials, and other modes of intercellular communication. Extracellular fluid tonicity is regulated almost exclusively by the amount…

Disorders of Childhood Growth

Introduction Human growth is an astonishing process. Its beginnings are intertwined with the enormously intricate mechanisms that transform a single cell into a complex embryo. Once formed, the human fetus and then child continue to grow over the course of approximately 15 years, reaching a body mass more than 10,000,000 times greater than that of the zygote from which the child originated. The early growth rate…

Monogenic Diabetes Mellitus: Neonatal Diabetes and Maturity-Onset Diabetes of the Young

Introduction Diabetes is a heterogeneous disorder with many different possible causes, both genetic and acquired. Risk for the most common causes, type 1 and type 2 diabetes, depends on many different gene loci with intermediate or low effects and are thus considered polygenic. However, approximately 1% to 5% of all diabetes is caused by abnormalities at a single gene or locus and as a group, these…

Disorders of Mineral Metabolism: Normal Homeostasis

Calcium (Ca), phosphorus (as phosphate [HPO 4 2− ]), and magnesium (Mg) are essential nutrients that are indispensable for the structural integrity of the body and for the function of each of its cells. The genetic and physiological mechanisms that regulate normal mineral homeostasis and bone development, composition, and strength from the prenatal period through adolescence are complex. Lists some of the many genes that direct…

Disorders of the Thyroid in the Newborn and Infant

Introduction The thyroid axis is probably the best example of the physiological interactions between the mother, the fetus, and their environment. The discovery of the crucial role of maternal iodine intake for the normal development of the fetus also led to the first successful intervention in preventive medicine. Two centuries ago, the idea to use iodine to treat endemic goiter, which predominantly affected women, encountered a…

Hypoglycemia in the Newborn and Infant

Introduction One of the most important metabolic events to mark the transition from fetal to neonatal life is the adaptation from an environment that has a readily available and continuous source of glucose—transplacental passage of maternal blood—to an environment in which glucose is provided in a limited and intermittent supply via feeding. At birth, after separation from the placenta, the complex mechanisms involved in the maintenance…

Ambiguous Genitalia

Introduction Throughout history, humans have sought to understand the differences between biological sexes and the mechanisms responsible for these biological differences. Normal gonadal differentiation and sex development depend on the meticulous choreography and synchrony of a network of endocrine, paracrine, and autocrine signaling pathways. This network involves the actions and interactions of specific genes, epigenetic influences, transcription factors, and hormones. Perturbations of the intricate network of…

Fetal-Maternal Endocrinology and Parturition

Overview Pregnancy is a complex physiological state consisting of a symbiotic relationship between two genetically distinct, but related, individuals: the mother and the fetus. The success of pregnancy requires dramatic alterations of maternal physiology to accept, protect, house, and nurture the fetal allograft. A successful pregnancy involves implantation of the developing embryo into the endometrium; its avoidance of immunological rejection by the maternal immune system; adaptation…

Endocrinology Laboratory Testing

Introduction What makes one an effective user of the clinical laboratory? Such a user: Identifies at least one sympathetic ally in the clinical laboratory to whom one can reach out for advice about laboratory testing. None of us can be expert in all the areas we need to know for the best possible care of patients, so including a laboratory expert as an ad hoc member…

Receptor Transduction Pathways Mediating Hormone Action

Introduction Hormones exert their actions by binding to specific receptor proteins, a process that induces conformational changes or compartmental redistribution of these proteins. The activated receptor is now capable of inducing positive (or negative) intracellular effects that ultimately are recognized as a physiologic response. The specificity of hormone action is determined by the affinity of hormones for different receptors, the cell-specific expression of the receptor, and…

Molecular Endocrinology, Endocrine Genetics, and Precision Medicine

Introduction The study of the endocrine system has undergone a dramatic evolution since the 1990s, from the traditional physiologic studies that dominated the field for many years to the discoveries of molecular endocrinology and endocrine genetics. At the present time, the major impact of molecular medicine on the practice of pediatric endocrinology relates to diagnosis and genetic counseling for a variety of inherited endocrine disorders. In…

Overview and Principles of Pediatric Endocrinology

Historical background Endocrinology is a discipline of science that seeks to understand how chemical signals secreted by cells regulate the function of distant (endocrine) or local (paracrine) tissues, or even their own function (autocrine), to integrate vital processes of life, such as growth, reproduction, and metabolism ( Fig. 1.1 ). Classical endocrinology derived from careful clinical observation such as, for example, the gigantism associated with pituitary…

Quality improvement and the clinician

Learning objectives By the end of this chapter the reader should: Be aware of the main quality issues relating to paediatric care Understand the concepts of quality improvement Be able to describe basic improvement tools Be able to provide examples of quality improvement in child health The concept of quality in healthcare and the understanding of its relevance and role have evolved over the past twenty…

Evidence-based paediatrics

Learning objectives By the end of this chapter the reader should: Understand basic principles of evidence-based medicine in order to implement it into clinical practice Be able to formulate a clinical question Be able to undertake a hierarchical search strategy using online search databases Be able to critically appraise a randomized controlled trial (RCT) Be able to interpret the commonly used measures of treatment efficacy Be…