UNIT BACKGROUND
The distinction between the well nourished and the not so well nourished is not clear cut, making the assessment process and the interpretation of findings relatively difficult. Because of the abundant food supply in this country, nutritional deficiencies generally exist as subclinical states. Overt or clinical nutritional deficiencies, although uncommon in the United States, have been demonstrated in certain population groups or circumstances. Primary malnutrition due to limited food intake has been reported among children in economically deprived populations such as in ghettos of the big cities, the Mississippi Delta, the foothills of Kentucky, and the coal fields of West Virginia. Malnutrition can also occur secondary to conditions creating physiological stress or acute illnesses: malabsorption, impaired nutrient transport and utilization, imbalance of nutrients, and drug-nutrient interactions. Unless nutritional intake is modified according to demand, malnutrition can result. Growing children and pregnant and lactating women, for instance, because of their physiological conditions, have greater nutritional requirements. Persons recovering from surgery suffer from loss of blood and tissues. Vomiting causes significant losses of ingested food and gastric juices; diarrhea can cause inadequate absorption of nutrients. An uncontrolled diabetic cannot utilize carbohydrates efficiently; loss of sugar in the urine represents loss of calories. Lastly, drugs can interfere with absorption and metabolism of many nutrients.
Overt nutritional deficiencies do not develop overnight since body tissues including blood represent a reserve of nutrients that can be called on during periods of short-term malnutrition. Chronic nutrient deficiency, however, can lead to desaturation of blood and tissue nutrient stores and can be determined by analysis of these tissues and the urine. Lesion at the molecular level may also occur during this period of subclinical deficiency, manifesting, for instance, in reduction of enzyme activity. When nutritional deficits occur over extended periods, clinical lesions indicative of overt or clinical nutritional deficiencies are manifested such as growth retardation, or problems with the eyes and parts of the mouth. The sequence of events leading to clinical nutritional deficiency can thus be summarized as follows:
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The objective of individual assessment of nutritional status is to establish whether problems are of nutritional origin and to define the person's nutrient requirements. Nutrition assessment is the first step toward the development of a nutritional care plan and toward the treatment of malnutrition as a result of either over- or undernutrition. The purposes of assessment is to classify clients in terms of nutritional risk, to identify those that are at high risk, and to use the findings as a basis for nutrition care planning.
Generally, the methods used in assessing nutritional status of individuals are:
- 1. Nutrition-related histories and dietary study, including supplements taken.
- 2. Anthropometric measurements.
- 3. Clinical or physical assessment.
- 4. Biochemical and/or roentgenogram studies.
- 5. Assessment of feeding skills and problem.
The assessment process could be lengthy and costly. Some of these methods may be omitted depending on the objective of the assessment, the nature of the presenting problem, age, and availability of resources and expertise. Nutrition assessment methods for some hospital patients are usually more in-depth and detailed. Select only the assessment methods that are appropriate for your client. Only brief descriptions of the methods are included in this unit with the goal of enhancing understanding and appreciation of the process.
Positive clinical findings should be distinguished between those caused by pathological conditions and those caused solely by nutrient deficiencies or excesses. Furthermore, such findings should be considered as clues rather than as diagnoses; a nutritionist, nurse, physician, or related health practitioner should be alerted to these findings in order to identify the cause of the symptoms.
The role of qualified health care professionals in the assessment of nutritional status varies from screening to a more in-depth assessment depending on the type of practice setting, the policies of the health care facility and knowledge/skill in the assessment process. In practice settings such as physician's offices, community health programs or ambulatory outpatient clinics, health care providers such as nurses often screen for health/nutritional problems and provide nutrition education and intervention. In hospitals, extended and long-term care facilities, or hospices, nutrition assessments are referred to dietitians/nutritionists. Recommended nutritional care plans are integrated into the total care of patients.
NUTRITION-RELATED HISTORIES AND DIETARY STUDY
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Through a review of medical and/or school records and an interview with the client and/or the client's parents or caretaker, information is obtained on environmental, social, cultural, economic, medical/dental (medication and health status), psychological, and physical influences on nutritional status. The type of question asked will depend on the age and presenting problem of the client. A classroom teacher or other school personnel can screen for some of this information and provide valuable background material when a referral is made to a nutritionist/physician.
Dietary study is used to assess the sources of nutrients and the adequacy of nutrient intake. Results of dietary studies provide a picture of nutritional status only when integrated with findings from clinical or physical assessment, biochemical analysis, and/or feeding observations..
There are a number of methodologies used to study the dietary intake of individuals. The objective is to obtain a diet that represents what a person usually eats. It can come from repeated 24-hour food recalls, from a 3-day (preferrably a weekend and two weekdays) estimated record of food intake, or weighed food record. The diet history method makes use of food records concurrent with a food frequency checklist. These records are integrated to obtain a usual or typical food intake over a selected time period.
After a typical day's diet is obtained, nutritional quality is assessed. Again, there are several ways to do this. A quick and simple way is to tabulate the kinds and amounts of foods according to food groups and to compare these to the respective recommended servings for each food group in the Food Pyramid Guide. A more time-consuming and technical method of assessing dietary intake is to calculate nutrient values, using a computer analysis program. See the Nutrient Analysis Tool at the University of Illinois.
Dietary nutrient values obtained are regarded as relative rather than absolute values since nutrient content of foods varies according to how food intake is reported, and to season as well as processing, storage, and distribution procedures. Food values reported in food composition tables represent average figures. The amount of nutrients ultimately utilized by the body further depends on the amount absorbed, which can be affected by many factors such as nutritional status, medication or drug use and presence of chemicals in the diet that favor or prevent absorption of specific nutrients.
The nutrient values of the diet are then compared to the RDA, RDI, or Tolerable Upper Intake Levels (UL) specific to age and sex. It has to be recognized, however, that the these recommendations are for groups. Therefore, an individual's failure to meet the RDA does not necessarily mean inadequate intake. For most nutrients, levels >66 percent of those recomemnded have been considered acceptable. Since magnesium and zinc values are available only from some foods, the cutoff point of an acceptable level for these minerals could be lower than 66 percent.
ANTHROPOMETRIC MEASUREMENTS
Anthropometric indices are direct measurements of the size, weight, and composition of the body. They are most useful for the growing child in assessing physical growth and development, especially when successive measurements are made at different times in the child's life. For the purposes of this module, only length/height, weight, and skinfold thickness will be discussed. The efficiency, accuracy and speed with which height and weight measurements can be made by trained personnel make them an ideal screening method for identifying nutritional problems.The need to obtain accurate measurements by using standardized equipment and careful procedures cannot be overemphasized. Assistance by a nutritionist/dietitian, nurse or physician is needed in the interpretation of findings.
Body weight can be measured using a balance-beam scale. The scale should be adjusted to zero prior to weighing. The infant scale permits weighing to the nearest 10 g or 1/2 oz; those for older children or adults should be measured to the nearest 100 gm or 1/4 lb using a platform scale. Infants are usually weighed without clothing, older children may be in their undergarments. The scale should be calibrated at least every three months, using standard weights.
Length, height, or stature measurements provide information on the
linear growth of the skeletal frame. Recumbent length is obtained for children
below 36 months and standing height thereafter. Length may be 
measured on a table or on a portable
measuring board. When using the latter, one person (a parent if possible)
holds the child's head against the fixed headboard while a second, trained
person holds the child's feet with knees and hips completely extended and
toes pointing up, and brings the movable footboard to rest firmly against
the child's heels. Many children are frightened by this procedure, and having
a parent nearby helps reassure them. Length or height readings are recorded
to the nearest 1 cm or 1/4 in. Measuring rods attached to platform scales
are not recommended for height measurements.
A measuring tape attached to a vertical surface gives a more accurate measurement. The child stands with bare heels together, back as straight as possible with heels, buttocks, shoulders, and head touching the vertical surface. A board, at right angles against the wall, is placed on the crown of the head and the measurement noted.
Stature and weight measurements can then be plotted
on reference charts prepared by the National Center for Health Statistics
and the Center for Disease Control. Growth charts have several dark curved
lines, the middle (50thpercentile) representing the mean value at the different
age levels. The other dark lines represent ranges within which normal measurements
fall.
Children are considered at nutritional risk when their
stature and weight measurements are less that the 5th percentile or more than
the 95th percentile. Values between the 5th and 10th and between the 90th
and 95th percentiles are considered borderline. Measurements and plotting
need to be repeated to check for accuracy.
Body mass index is used to identify adults who are
at health risk. BMI is a mathematical formula (BMI=kg/m2) which correlates
highly with body fat and health risks associated with obesity. These include
Type 2 diabetes, hypertension, dyslipidemia, gallstones, cholecystitis, some
forms of cancer, and respiratory disfunction.
Skinfold thickness is another anthropometric measurement which measures,
using a caliper, the amount of fatty tissues in selected sites where fat is
generally deposited. The tricep skinfold (posterior midpoint between the left
acromion or tip of shoulder and olecranon or elbow) is the site most frequently
used. The results are compared to standard skinfold graph (see Frisancho,
A.R. under Suggested Readings). Skinfold thickness is more sensitive than
weight measurement in distinguishing fatness since the latter measure cannot
distinguish a heavily muscled person from a fat one when both are of the same
weight. Skinfold thickness is not, however, a useful measurement for hypotonic
infants and children since it measures not only fat but also muscles.
CLINICAL ASSESSMENT
Clinical assessment consists of a physical examination for discernible signs and symptoms of malnutrition,which include pathological changes in the skin, eyes, lips, hair, and teeth as well as subtle visible changes in bone shape or the size of internal organs. Clinical signs are the end result of relatively long-standing unmet nutrient needs. They are indicators of serious nutritional ill-health, and children with long-term feeding and eating problems are at particularly high risk. Positive findings should be distinguished between those caused by pathological states and those caused solely by nutrient deficiencies or excesses (see Glossary: Selected Signs of Malnutrition). Furthermore, such findings during screening should be considered as clues rather than as diagnoses; a nutritionist or physician should be alerted to these findings in order that appropriate biochemical analysis, roentgenograms, or nutrition assessment, etc are made to identify the cause of symptoms.
BIOCHEMICAL AND ROENTGENOGRAM STUDIES
Analysis of blood and urine nutrient levels is important in confirming or disproving the existence of nutritional deficiencies determined questionable through dietary study and clinical assessment. The earliest signs of nutritional problems are biochemical rather than clinical. In other words, before the person experiences any unusual or uncomfortable symptoms and before any signs or symptoms are observed during a physical examination, there are subtle changes in body tissues that can only be detected using laboratory techniques. Biochemical analysisis one of the most objective methods in nutrition assessment since it is not influenced by bias on the part of the person being evaluated or on the part of the evaluator.
Blood, serum, and urine have been studied for a variety of nutrients and metabolites. Blood or urine tests generally measure levels of nutrients or their functional activity. Nutrient levels may indicate current or past nutritional status. For instance, ascorbic acid and B vitamin levels reflect current dietary intakes whereas protein levels reflect long-term dietary intake. Levels of enzymes are indicative of functional activity and assess vitamin status.
Laboratory tests are generally ordered by the physician. The tests are expensive, require specialized equipment, and tend to evoke negative responses from children. Therefore, it is not feasible to routinely perform a full range of analyses. Usually, specific tests may be selected based on the child's disorder, nutritional history, dietary intake, and results of the physical examination. For instance, determinations of hemoglobin and hemocrit levels are suggested for preschoolers since a high incidence of iron deficiency anemia has been reported for this age group. Folic acid, alkaline phosphatase, and calcium determinations are indicated for persons who are on anticonvulsant therapy. Alkaline phosphatase is an enzyme associated with bone demineralization, and high levels indicate possible withdrawal of calcium from or deficient calcification of the bones resulting in a condition known as rickets. The diagnosis of rickets may be confirmed by roentgenographic studies of the hand and wrist. X-ray of the wrist is also useful in determining skeletal age and predicting adult size. Ascorbic acid and tryptophan load tests are not routinely used to assess vitamin C and pyridoxine status, respectively. (Results of both these tests are reported in this unit since Kirk was one of a group of children who were part of a study on vitamin status conducted by the author).
ASSESSMENT OF FEEDING SKILLS
A thorough understanding of normal infant and child growth and development is essential in order to be able to identify abnormal patterns and to design the appropriate therapy. The feeding assessment involves observation of oral structures and functions such as breathing, sucking, chewing and/or swallowing while the child or person is being fed or is eating. It is important to remember that development follows an orderly pattern, and that it proceeds from general to specific. Thus, a child needs to possess hand-to-mouth motions, a general pattern, before being able to hold a spoon, a specific activity. Difficulties in feeding and eating may be attributed to neuromuscular dysfunction, anatomic defects or mechanical obstruction of the oral-gastrointestinal tract, behavioral and dental problems, or a combination of these causes.