Nutritional assessment

Nutritional assessment

Malnutrition is a common problem worldwide, and in developed countries it is associated particularly with poverty and alcoholism. It is also encountered among patients in hospital. Various studies have shown that patients may have evidence, not only of protein-calorie malnutrition, but also of vitamin and mineral deficiencies, especially after major surgery or chronic illness.

Malnutrition to the layman usually means starvation, but the term has a much wider meaning encompassing both the inadequacy of any nutrient in the diet as well as excess food intake. The pathogenesis of malnutrition is shown in Figure 52.1.

Fig 52.1 The development of malnutrition.

Malnutrition related to surgery or following severe injury occurs because of the extensive metabolic changes that accompany these events: the ‘metabolic response to injury’ (pp. 110–111).

The assessment of a patient suspected of suffering from malnutrition is based on:

laboratory investigations including biochemistry.

History

Past medical history may point to changes in weight, poor wound healing or increased susceptibility to infection. The ability to take a good dietary history is one of the most important parts of a full nutritional assessment. Taking a dietary history may involve recording in detail the food and drink intake of the patient over a 7-day period. More usually, however, a few simple questions may yield a lot of useful information about a person’s diet. Depending on the background to the problem, different questions will be appropriate. For example, in the wasted patient, questions about appetite and general food intake may suggest an eating disorder such as anorexia nervosa, but in the patient presenting with a skin rash, details of the specific food groups eaten will be required to help exclude a dietary cause. In the patient at increased risk of coronary heart disease, questions on saturated fat intake may be most revealing.

Examination

Simple anthropometric measurements will include height, weight, arm circumference and skin-fold thickness.

Body mass index (weight in kg divided by the height squared in metres) is a reasonable indicator of nutritional state, except when the patient is oedematous. Arm circumference is an indicator of skeletal muscle mass, while skin-fold thickness is proportional to body fat levels. In addition, general physical examination may reveal signs of malnutrition in the skin, nails, hair, teeth and mucous membranes.

Biochemistry

A number of biochemical tests are used to complement the history and examination in assessing the general nutritional status of a patient. None are completely satisfactory and should never be used in isolation. The most common tests include:

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Tags: Clinical Biochemistry An Illustrated Colour Text 5e

Jun 18, 2016 | Posted by admin in BIOCHEMISTRY | Comments Off

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