Useful Parameters and Landmarks

Measurements of length, weight, and head circumference are standard measurements of a physical examination. These three measurements are the parameters against which all others are compared. They document growth and body proportions. They should be obtained routinely at every visit to a physician in order to be able to assess longitudinal growth and growth relative to an age- and sex-matched standard. Curves of normal standards of growth, weight, and head circumference are included in every text on pediatrics. They usually start from birth and continue until 18 or 20 years of age. In this book, we have chosen the most commonly used standards and taken the liberty, for practicality, of combining some curves. Although the purist may question this process, we do not think it will markedly affect accuracy in most cases, and we hope the easy utilization of having only one curve will encourage regular and complete measurement. We have included geographic data when available, or markedly different (e.g., North America and North European heights). Unfortunately, ethnic comparisons of most areas of the body are not available.

Ultrasound examination permits monitoring of fetal development (Chapter 15). Routine measurements include biparietal diameter (BPD), crown-rump length, chest circumference, and femur length. These are useful standards with which to observe the well-being of the fetus prior to birth.

Head circumference (OFC) is looked upon as one of the most important measurements in infancy and early childhood, since it reflects intracranial volume and brain growth. The head circumference charts chosen for this book are the ones most widely used. Often centers will have their own OFC charts, related to the population and ethnic groups that they serve (Chapter 6).

When length, weight, or head circumference deviate from the normal growth curve, further investigation is warranted. Many different pathological processes, some of which may be treatable, can lead to growth failure. Discrepancies in growth proportions may provide clues to the pathological process; for instance, chronic infection and renal failure lead to relative loss in weight, while growth hormone deficiency and Cushing syndrome produce relative increase in weight. Usually, by two years of age a child has established a pattern of growth that will predictably follow percentile growth curves. These growth curves, on average, are similar for OFC, height, and weight. During the first year of life a child may change percentile growth curves as he or she establishes an extrauterine growth pattern.

Bone age is an additional parameter of growth that reflects physiological growth. Bone age is determined from radiographs of the hand

Measurements in Dysmorphology and Clinical Genetics or other epiphyseal centers (different ones for different ages). If a disturbance of normal growth is suggested, additional X-rays may be necessary (Chapter 13).

Weight and skinfold thickness will be of special value in nutritional problems (Chapter 5).

During adulthood, particular measurements may also reflect an underlying pathological process. Routinely, weight and total body length are measured in the adult, but head size is often excluded because the head usually does not grow in the normal adult. Familial patterns of growth "late-bloomers") and disproportion (large heads or "short waisted") may identify genetically determined influences on growth.

One should always include the measurements of the parents of the child under assessment so that mid-parental parameters can be established for comparison. This is particularly important and appropriate when evaluating deviations from normal of head size and height.

Growth velocity is most rapid immediately after birth and up to three years of age, after which there is a continued deceleration of growth until puberty. The adolescent growth peak in girls is at approximately 12 years, and in boys at approximately 14 years of age. It is useful to compare growth at yearly intervals, although in infancy shorter time intervals will be used because the velocity is greater.

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