Continuing Education Activity
Anthropometry, or the measurement of body parameters, helps in the diagnosis of malnutrition and obesity. Height assessment is essential from a clinical, anthropological, and forensic standpoint. It is an absolutely critical part of the well-child visit and can aid in diagnosing multiple conditions. This activity describes the significance associated with height assessment, the different methods that can be used for its assessment across age groups, and the methods employed for skeletal remains in forensic science. These methods often require a deeper understanding of the subject, best known to trained nursing staff and clinicians. It is an essential skill that requires consistent methods of practice to ensure reliable measurements are obtained.
- Identify the importance and associated indications of height assessment.
- Describe the equipment, personnel, preparation, and technique recommended for height assessment.
- Review the potential complications in performing height assessment.
- Explain the clinical significance of performing height assessments.
Anthropometry, or the measurement of body parameters, helps diagnose malnutrition and obesity. It is a vital part of pediatric evaluations as well as the assessment of an adult. Body height is one of the main anthropometric measurements obtained in children. The measured value is compared to a reference population and monitored over time to ensure adequate growth.
The World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC) have implemented standardized procedures for measuring body height to ensure reliability and accuracy. Additional methods have also been developed to ensure height assessment is obtained in children with physical disabilities, preventing accurate measurement by standard methods.
Height assessment is a noninvasive, readily obtainable measurement that can help identify children at risk of malnutrition or obesity. However, a need for universal and accurate measurement of height remains. A multicenter randomized trial in primary care practices in the United States deemed only 30% of height assessments accurate (within 0.5 cm of the height obtained by a trained anthropometrist). The accuracy rate in inpatient settings is even more dismal.
The stature or height of an individual is an inherent characteristic that has clinical implications in assessing nutritional status, estimating body mass index (BMI), and diagnosing underlying disorders in children and adults. Furthermore, height assessment requires special consideration when evaluating patients with limb and/or spine deformities, trauma, skeletal dysplasia, and hospitalized patients. This article reviews the standardized methods of height assessment, their clinical significance, and implications to help improve the clinical accuracy of this measurement and patient outcomes.
Physical growth is a process with its trajectory inching towards attaining a fully developed adult form. Stunted growth in children indicates either genetic dysfunctions or inadequate nutritional fulfillment. Early detection of such conditions through the regular monitoring of growth indicators such as height and body weight can diagnose these conditions at an early stage leading to early modifications and treatments. In some cases, this may result in “catch-up” growth in the child. Height measurement in adults fulfills a similar function by indicating the physical health status of individuals. In older adults, it can identify those at risk for osteoporosis and fractures.
The World Health Organisation (WHO) growth standards can be used to monitor the physical growth and development of children and infants. It estimates the percentile and z-scores for length/height for age, weight for age, weight for length, weight for height, and BMI for age. The standards depict normal early childhood growth under optimal conditions. These various parameters listed under the growth chart can be used to diagnose growth disorders or address the nutritional needs of children regardless of their ethnicity, socioeconomic status, and type of feeding.
The Child Health and Disability Prevention (CHDP) Program Health Assessment Guidelines (guideline #4) recommend anthropometric measurements in all children and adolescents at each preventive visit to ensure adequate growth patterns and to assess the risk of obesity. The obtained measurement should be plotted on World Health Organization (WHO) charts or the CDC charts, which are gender and age-specific, to compare the child to the average population. Accurate serial measurements over time are the most important aspect of anthropometry. Solitary deviations from a growth pattern curve can be a normal variant or due to an acute illness. However, according to the CHDP guidelines, a steady change of the growth curve on serial measurements is a reliable indicator of an abnormal growth pattern and warrants further workup.
In adults, anthropometric measurements are recommended at each well-visit to determine nutritional status and the risk of future disease.
Anthropometric measurements are noninvasive and, as such, do not have any contraindications for their use. There are situations in which the measurements might give inaccurate results (such as acute illness). Using anthropometric measurement in such situations can provide falsely reassuring or alarming data and should be avoided.
Height assessment can be estimated using the patient's wingspan or directly measured with a tape measure or stadiometer. Using wingspan to estimate height or a tape measure for direct measurement yields inaccurate measurements compared to the gold standard method utilizing a stadiometer. According to the CDC, a stadiometer is the preferred equipment to assess height. It should be calibrated to measure height to the nearest one-eighth inch. Commonly utilized methods of height assessment are listed below.
Commonly Used Instruments for Measuring Height
- Measuring tape
- A horizontal length scale (HLS) is a flexible horizontal scale used to measure an infant's recumbent length.
- Infantometer. The infantometer measures the recumbent length of an infant with greater accuracy by securely holding the infant in position.
- Anthropometer rod. The anthropometer rod consists of four equal rods and can be used to measure height up to a range of 2 meters.
- Stadiometer. The stadiometer consists of a ruler and a sliding horizontal headpiece which can be fixed above the head to measure height.
- Osteometric board. It is an anthropometric instrument consisting of a flat board with a fixed end and a crosspiece. It is used to measure the length of long bones.
Isolated anthropometric measurements are not useful. The values obtained must be compared to relative standards for the appropriate population. The Centers for Disease Control and Prevention (CDC) charts are obtained from children raised in various nutritional conditions in the United States. The World Health Organization (WHO) charts outline the growth of healthy children under optimal nutritional and environmental conditions, providing a 'goal' standard for optimal growth.
On the CDC charts, the normal growth pattern is identified as growth between the 5th and 95th percentiles. The WHO charts are considered applicable to all children from birth to five years of age regardless of ethnicity, socioeconomic status, and type of feeding. On WHO charts, the normal range is defined between two standard deviations above and below the mean or z-scores between -2.0 and +2.0. This corresponds to a range between the 2nd and 98th percentiles. A comparison between the two charts showed that the WHO growth standards are less likely to classify a child as undernourished than the CDC charts.
When using growth charts, it is essential to use the correct chart for the patient's age and gender. It is also important to remember that children with disorders that alter the growth pattern need specialized plots to obtain meaningful results. A number of specialized growth charts have been developed for children with Down syndrome, Turner syndrome, cerebral palsy, Williams syndrome, achondroplasia, Prader-Willi syndrome, and Rett syndrome and should be used in place of standardized growth charts when indicated.
Growth Chart Correction for Prematurity
It is important to correct growth parameters for gestational age in children with prematurity. This is done by subtracting the number of weeks the infant was born preterm from the postnatal age. This correction should continue for two years of age if the child is born before 32 weeks of gestation. For children born between 32 and 36 weeks of gestation, the correction should be continued for at least 12 months of age.
A portable laser height meter was tested in comparison to a stadiometer in a 2020 study which revealed reproducibility within and between different operators along with acceptable accuracy when compared to a stadiometer. This device may prove to be useful in patients when standing height cannot be obtained or in the evaluation of remote populations when the use of a stadiometer may be difficult.
Clinical nurses and assistants can reliably and accurately obtain height measurements in pediatric and adult populations. Although traditionally, home measurements performed by parents/caregivers have been noted to have considerable variation and error, this can be corrected with adequate training. In the era of remote medicine, this may be particularly useful. A recent study stated that remote height and weight collection could be obtained with minimal differences in the various measurement methods after proper training.
Height Assessment in Infants
Height measurement in infants poses a problem, given their small size, limited control over their body, and inability to follow instructions. In infants, the attribute of height goes more commonly by the term “recumbent length” or “crown-heel length.” The recumbent length of an infant can be measured using a simple horizontal length scale (HLS), tape measure, anthropometric rod, or an infantometer. To measure the length of the infant, clothes, diapers, hair ornaments, and objects of similar nature require removal. The head gets placed against the headboard in the Frankfurt vertical plane with the body in the supine position. The infant is then positioned along the center of the device with the footboard against the soles of the feet. The length is noted to the nearest millimeter. Using the HLS frequently invokes a crying response from the infant. The parent or caregiver should be as close as possible to soothe the child during this measurement. This helps in obtaining an accurate measurement.
Surrogate measures to full-length measurement in infants offer certain advantages over conventional methods. They permit length estimation through formulae and are often more accurate than full-length measures. Additionally, they offer an insight into the differential growth of body segments as a function of age, sex, ethnicity, and pathological conditions. Alternative measures researched include arm span and ulnar length.
Height Assessment in Children
Height is measured in children (aged 3 or more) through the use of a stadiometer or an anthropometer rod. The preferred method outlined by the CDC is described below.
The stadiometer is mounted on the wall for this purpose, and the child is asked to remove any footwear and/or head ornaments before noting the measurement. With the buttocks, the shoulder blades, and the back of the head against the board, the head is oriented in the Frankfurt horizontal plane (FH plane), and the headpiece gets firmly placed on the head. The reading is noted to the nearest tenth of a centimeter. The head is in the Frankfort horizontal plane when the horizontal line from the ear canal to the lower border orbit is parallel to the floor. The line must also intersect the vertical backboard perpendicularly. The child should be asked to take a deep breath and stand as tall as possible. A deep breath straightens the spine and allows more accurate and consistent measurements.
An alternative to standing height measures in children is the sitting height, measured from the vertex (topmost point of the head) to the sitting surface after orienting the head in the Frankfurt horizontal plane. The stadiometer is placed on a stool at a sufficient height to allow the participant’s legs to form a 90 angle with the ground. Bone age in children is also useful as an indicator of height (as given in the Bayley and Pineau table).
Height Assessment in Children with Skeletal Dysplasias
Modifying the height assessment technique in children with known dysplasia is critical for adequate nutritional assessment of these children. Height assessment can also help screen for these disorders as well. A study comparing sitting height to standing height in the United States revealed that sitting height-to-standing height ratio assessment detected disproportionate short stature in children with skeletal dysplasia. They recommended standardized ancestry-specific reference charts with this measurement to screen for skeletal dysplasia in children.
The arm span is essential in patients suspected of having skeletal dysplasia. It is obtained by measuring the length of both arms (from the tip of one middle finger to the other) outstretched perpendicular to the body axis. This is best obtained with the infant lying against a flat surface. A mark is placed at the tip of the middle finger of each outstretched arm. The length is then measured after the child is moved. The arm span is equal to or greater than the height in children. Even in adults, it should never exceed the height by more than 10 cm. A decrease in the arm span is suggestive of shortening of the upper extremities and warrants evaluation for achondroplasia or other skeletal dysplasias that affect the long bones.
In patients with known spinal or skeletal deformities, alternative measurements to assess linear growth include upper arm length and knee height. Standard curves exist for these measurements and should be utilized in these patients. In children with severe cerebral palsy, direct measurement of length in the supine position is the most reliable way to assess height and minimize error.
In patients with idiopathic scoliosis, a diurnal variation of body height in children is noted, with a significant decrease in body height during the day. This is seen in both standing and sitting positions. A 2019 study reported a decrease of 0.7 cm (+/- 0.7) for standing position and sitting positions in these patients, with the greatest decrease in height occurring in late afternoon and evening times. The authors recommended recording the time of day when assessing height in these patients to ensure adequate comparisons over time.
Height Assessment in Adults and the Elderly
The most common method used for measuring height in the case of adults and the elderly is through the use of a stadiometer or an anthropometer. Regression equations for arm span, lower leg, foot length, shoeprint length, and recumbent length may also be used in the case of the elderly as indicators of stature when standing height cannot be measured. Radiological methods such as x-rays and CT of long bones have also been used to estimate stature in these patients.
Height Assessment from Skeletal Remains
Stature estimation from complete skeletal remains - Dwight (1894) piloted the method for stature estimation from complete skeletal remains. Using the complete skeleton involves summing up measurements of all the skeletal elements, followed by adding a correlation factor for soft skin and muscles. Fully (1956) individually measured the skull, the vertebral column from C2-S5, the femur and tibial length, and the height of the calcaneus and talus. He then summed up these measurements to obtain skeletal height. Adding a soft tissue correction factor can help estimate the living stature of the same individual.
Stature estimation from long bones and fragmentary skeletal remains- The former method requires the presence of the entire skeleton, which is not available in its entirety many times. In such situations, fragmentary skeletal remains are used. Research has shown cephalometric measurements to correlate with stature in the case of males and a correlation of craniometric measurements with stature in both males and females. Additionally, the bones of the body, including the sternum, sacrum, phalanges, calcaneum, and long bones, may be used to estimate the stature of the remains.
Early research on deriving regression equations using long bones was carried out by Karl Pearson (1899), Pan (1924), Nat (1931), and Trotter- Gleser (1958), while research on using fragments of long bones was done by Steele and Mckern (1969). Tibia and femur have proved to be the best indicators of stature in individuals after considering the error margin. The length of these individual bones may be measured using an osteometric board. One end of the bone to be measured is placed at the fixed end of the board, and the other end is held in place using a crosspiece. The reading on the corresponding scale gives the physiological length of the bone.
As stated before, diurnal variations in height can be a source of error. Stature varies at different times of the day by up to 2 centimeters, with a reduction seen in the afternoons and evenings due to reduced elasticity of the intervertebral discs and vertebral muscles. This, along with the gradual reduction in height due to senile degeneration, must be considered when using stature as an identification parameter or for clinical diagnosis.
Clinically, height is necessary for maintaining physical growth records. This is especially significant when it comes to monitoring the growth patterns of infants and children. Growth indicators such as the individual's height and BMI can help diagnose malnutrition in children. In adults, height loss can predict future disease processes and help prevent adverse outcomes in these patients. For example, height loss in older women is predictive of osteoporotic fractures and increased morbidity and mortality. Regular height assessments in adults can help diagnose height loss early, which may help prevent future fractures in these patients.
In the current era of childhood obesity, an accurate measure of height is even more critical in diagnosing children at risk of obesity. Height assessment is required to calculate BMI and is a central data point for calculating waist-to-height ratio (WHR). Both measure are important in assessing growing children for obesity, particularly central obesity, which has significant clinical implications for their future health. An accurate height and weight assessment can also be used to measure fat mass using a height–weight equation. This inexpensive and readily available method was found to be as accurate as dual-energy X-ray absorptiometry and bioelectrical impedance measurements in this study.
The significance of measuring the height of individuals for an anthropological setting comes into play while studying the physical growth patterns and secular trends across regions and population groups. We cannot apply established data for a particular population to other populations and hope to expect accurate results. Population-specific height assessments can help identify areas of concern and target populations. In the context of an overall increase in average heights worldwide, a decline in the average height of adults in a specific population warrants inquiry into factors that may be causing this trend. Evaluating average height in India over two decades, a study underlined the need to examine the non-genetic factors leading to a trend toward the decreased height of the population.
Assessment of Abnormal Growth CurvesWhen a deviation from the expected growth pattern occurs in the height assessment of a child, a systematic approach to this abnormal growth is warranted. As stated before, a single value at any particular point in a child's life is of limited use. A growth rate that accelerates or decelerates, moving across percentiles, warrants further evaluation. When abnormal growth is suspected, the first step is to ensure the accuracy of the data. It is also important to remember that growth is a discontinuous process. The smooth growth curves seen in standardized charts can be misleading. Studies have shown that growth, particularly length, during the first 21 months of life occurs only during discrete periods. This is important because a seemingly decelerated growth may be nothing more than a "normal growth-free" period in a child's life.
Consequently, children with short stature who have normal growth rates and normal bone age have a genetic short stature and do not require further evaluation/workup. However, children with short stature and decreased growth rates need a comprehensive evaluation for an underlying pathologic condition. A pathologically increased height is quite uncommon.
Enhancing Healthcare Team Outcomes
Even though the general presumption is that height assessment is a part of the preliminary examination/routine check-ups carried out at hospitals and health care centers, it has many other underlying indications too. As previously described, it can indicate several abnormalities in individuals and be used to diagnose these conditions. However, to arrive at a correct diagnosis and accurate assessment, the recommended methods of height assessment should be followed rigorously. The measurement tools should be calibrated regularly, and proper training of the staff should be ensured.
Diagnosis of clinically significant conditions requires trained nursing staff to aid in the process of measuring height, and its correct interpretation requires the involvement of clinicians. Better outcomes are possible by involving an anthropologist. Based on the accurate assessment of height, anthropologists can help shed light on varying growth patterns across regions and populations and use this information to indicate abnormalities, if any. A well-coordinated interprofessional team of nurses and clinicians can improve the accuracy rate of height assessment in patients, which will provide a better overall health assessment of the population as a whole. [Level 5]