childhood disease and disorder

childhood disease and disorder, any illness, impairment, or condition that primarily affects infants and children, spanning the period from fetal development through adolescence.

Childhood is a time of constant transformation—both within the child and in the world around them. The physical and developmental changes are so dramatic that it can seem as though a child becomes a series of different, yet connected, individuals as they move through infancy, childhood, and adolescence. At the same time, the environment shifts: the sheltered world of a dependent infant gradually expands into the broader experiences and responsibilities of an increasingly independent adolescent. To understand health and disease from conception through adolescence, it is essential to view them within this ever-changing context.

Although, for the most part, the diseases of childhood are similar to those of the adult, there are several important differences. For example, certain specific disorders, such as precocious puberty, are unique to children; others, such as acute nephritis—inflammation of the kidney—are common in children and infrequent in adults. At the same time, some diseases that are common in adults are infrequent in children. These include essential hypertension (high blood pressure of unknown cause) and gout. Finally, a major segment of pediatric care concerns the treatment and prevention of congenital conditions.

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Diseases in children are also characterized by a host of other features. Infectious diseases are prevalent and remain a leading cause of death in children. Examples include measles, polio, varicella (chicken pox), and mumps. Disorders of nutrition are also of concern, especially but not exclusively in less-developed countries. The major environmental hazards that endanger the health of young children are either unavoidable, as in air pollution, or accidental, as in poisoning and in traffic injuries. Similar to adults, older children, especially adolescents, may be exposed to environmental hazards that they deliberately seek, such as cigarette smoking and the use of alcohol and other drugs.

Diagnostic considerations

Diagnosis of the diseases of childhood involves special considerations and techniques; for example, in evaluating genetic disorders, the patient and family may need to be examined. Inapparent environmental causes of diseases, such as poisonings, must be considered and investigated thoroughly. Diseases of the fetus may derive directly from conditions that affect the mother or may be caused by drugs administered to her. Diagnostic techniques permit sophisticated examination of the fetus despite its apparent inaccessibility. The withdrawal of a small amount of the amniotic fluid that surrounds the fetus permits examination of fetal cells as well as the fluid itself.

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Chromosomal and biochemical studies at various stages of development may help to anticipate problems in the postnatal period; they may indicate the need for immediate treatment of the fetus by such techniques as blood transfusion; or they may lead to the decision to terminate pregnancy because serious, untreatable disease has been recognized. Other specialized techniques permit examination of the fetus by X-ray and ultrasound, and by electrocardiography and electroencephalography (methods for observing and recording the electrical activity of the heart and the brain, respectively). Fetal blood can be obtained for analysis, and certain techniques permit direct viewing of the fetus.

Because adult norms cannot be applied to younger age groups, pediatric diagnosis requires knowledge of each stage of development, with regard not only to body size but also to body proportions, sexual development, the development and function of organs, biochemical composition of the body fluids, and the activity of enzymes. The development of psychological and intellectual function is equally complex and requires special understanding. Since the various periods of growth and development differ so markedly from one another, they are divided for convenience into the following stages: prenatal (conception to birth), infancy (birth to about 1 year), early childhood (1–3 years), preschool (3–5 years), middle childhood (roughly 6–10 years), late childhood and preadolescence (about 10–12 years), and adolescence (generally 12–18 years and sometimes into early 20s, depending on context). Using established milestones for each stage of development, the child’s condition be adequately evaluated and the results of diagnostic tests properly interpreted. Thus, it is of no concern if a 12-month-old infant is unable to walk alone, although some infants are able to do so at nine months of age. The crucial question is at what age one becomes concerned if a developmental milestone has not been reached. Five-year-old boys average 40 to 42 pounds (18.1 to 19.1 kg), with a typical healthy range of approximately 34-52 pounds (15.4–23.6 kg). The hemoglobin level that is of no concern in the three-month-old infant may reflect a serious state of anemia in the older child. The blood levels of certain enzymes and minerals differ markedly in the rapidly growing child from those in the late adolescent, whose growth is almost complete. Failure of a 15-year-old girl to have achieved menarche (the beginning of menstruation) may be her natural sexual development but requires careful evaluation.

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Treatment and prevention

Treatment of childhood disease requires similar considerations with regard to various stages of growth and development. Variation in drug dosage, for example, is based not only on body size but also on the distribution of the drug within the body, its rate of metabolism, and its rate of excretion, all of which change during development. The inability of infants and small children to swallow pills and capsules necessitates the use of other forms and alternate routes of administration. The nutritional requirements of the growing child must also be considered when treatment requires modification of the diet or administration of drugs that may affect the absorption or metabolism of essential nutrients.

The outlook for recovery from disease in children is often better than it is for adults. A bone fracture that results in permanent deformity in the adult, for example, may heal with complete structural normality in the child, as continued growth results in remodeling and reshaping of the bone. Ultimately, the infant who has one kidney removed because of infection or tumor most likely will have healthy renal function because the remaining kidney will increase its size and functional capacity with growth. In contrast, removal of one kidney in the adult usually results in a residual functional capacity equal to 70 to 75 percent of that of two kidneys. Thus, being in a period of rapid growth and development may favorably affect the child’s recovery in the course of a disease. The converse may also be true, however. The rapidly growing and maturing central nervous system, for example, is particularly susceptible to injury during the first two or three years of life; also, adolescents may react unfavorably to psychological stresses that are tolerated readily by more mature individuals.

Infant and childhood mortality rates declined markedly since the mid-20th century, owing to the development and application of preventive measures. Widespread immunization against common infectious diseases has been central to improvements in survival among infants and young children. Socioeconomic factors—such as better maternal nutrition and obstetrical care and improved housing, water supplies, and sewage disposal—have also been of importance in this decline.

By comparison, an increased capacity to treat diseases, even with such powerful tools as antibiotics, has had relatively little impact. In more developed countries, where the most common causes of childhood morbidity and mortality are accidents, prevention depends upon a willingness to design and modify communities and homes to make them safer for children. In addition, just as important as the development of public health measures is their practical application; underutilization of established procedures and techniques for disease prevention, especially vaccination, is a major concern.