To assess a person’s nutritional status, a doctor asks about diet and medical problems, performs a physical examination, and orders certain laboratory tests. Blood levels of nutrients and substances that depend on nutrient levels (such as hemoglobin, thyroid hormones, and transferring) are measured.

To determine a person’s diet history, the doctor asks what foods were eaten in the previous 24 hours and what types of food are usually eaten. The person may be asked to keep a food diary, in which he lists everything he eats for 3 days. During the physical examination, the doctor observes the person’s general appearance and behavior as well as the distribution of body fat and assesses the functioning of body organs.

Nutritional deficiencies can cause a number of medical problems. For example, gastrointestinal bleeding can cause iron deficiency anemia. A person being treated with high doses of vitamin A for acne may develop headaches and double vision as a result of vitamin A toxicity. Any body system can be affected by a nutritional disorder. For example, the nervous system is affected by niacin deficiency (pellagra), beriberi, vitamin B6 (pyridoxine) deficiency or excess, and vitamin B12 deficiency. Taste and smell are affected by zinc deficiency. The cardiovascular system is affected by beriberi, obesity, a high-fat diet leading to hypercholesterolemia and coronary artery disease, and a high-salt diet leading to hypertension. The gastrointestinal tract is affected by pellagra, folic acid deficiency, and alcoholism. The mouth (lips, tongue, gums, and mucous membranes) is affected by a deficiency of B vitamins and scurvy. An enlarged thyroid gland may result from iodine deficiency. A tendency to bleed and skin symptoms such as rashes, dryness, and swelling from fluid retention (edema) can occur in scurvy, vitamin K deficiency, vitamin A deficiency, and beriberi. Bones and joints are affected by rickets, osteomalacia, osteoporosis, and scurvy.

A person’s nutritional status can be determined in several ways. One is to measure height and weight and compare them with those in standardized tables. Another way is to calculate body mass index-the weight (in kilograms) divided by height (in meters squared). A body mass index of 20 to 25 is generally considered normal for men and women.

ADVERTISEMENTS:

Still another way to assess nutritional status is by measuring skin fold thickness. A fold of skin on the back of the upper arm (the triceps skin fold) is pulled away from the arm so the layer of fat beneath the skin can be measured, usually with a caliper. Fat beneath the skin accounts for 50 percent of body fat. A skin fold measurement of about l/2 inch in men and about 1 inch in women is considered normal.

Nutritional status can also be assessed by measuring the circumference of the left upper arm to estimate the amount of skeletal muscle in the body (lean body mass).

X-rays can help determine bone density and the condition of the heart and lungs. They can also detect gastrointestinal disturbances caused by malnutrition.

When a doctor suspects severe malnutrition, he may order a complete blood cell count and blood and urine tests to measure levels of vitamins, minerals, and waste products such as urea. Skin tests may also be ordered to assess certain types of immunity.