Biology of Disease

used in isolation, as their findings are also altered in some disease states.
Hair and nail samples are of questionable clinical value and are not routinely
taken.

Protein-Energy Malnutrition

A diagnosis of PEM must identify the type present. Individuals affected by
maramus present with decreased anthropometric measurements, loss of
muscle mass and body weight. There is also a decline in body temperature,
pulse and metabolic rate. Serum protein levels are often low but can be
normal. Children suffering from PEM have reduced rates of growth and are
shorter, particularly in marasmus, compared with their normal counterparts.
This can be easily assessed using charts of growth rates (Figure 10.37). They
also have an impaired immune system, because of reduced protein synthesis
in particular of immunoglobulins, and, as a consequence, infections such
as measles that a child would normally be expected to survive are common
causes of death in severe cases. A diagnosis of kwashiorkor is made following
a thorough physical examination together with a medical and dietary history.
Patients affected with kwashiorkor have the characteristic swollen abdomen,
show hypoalbuminemia and a reduced lymphocyte count or lymphopenia.

INVESTIGATING NUTRITIONAL DISORDERS

CZhhVg6]bZY!BVjgZZc9Vlhdc!8]g^hHb^i]:YLddY '+,

Figure 10.37 A generic growth chart. Charts are

Age available for different sexes and ethnic groups.

Height

Normal growth

Deficient growth

97%

50%

3%

Obesity

In addition to arm circumference and skinfold thickness, the distribution
of fat in obese patients can be assessed by determining the waist : hip ratio.
The waist circumference is measured at its narrowest point and divided by
that of the hip at its widest. Ratios greater than 0.80 for women and 0.95 for
men increase the risk of developing clinical problems associated with obesity
(Table 10.7). Ultrasonography can also be used on soft tissue adipose material.
The technique reflects ultrasound waves from internal tissues or organs and
the echo patterns are analyzed to form a picture of body tissues called a
sonogram. The extent of fat deposition can be accurately determined but is
more expensive than other methods and not widely used.

Anorexia Nervosa and Bulimia Nervosa

Anorexia nervosa and BN are difficult to identify, given that the patients often
take extreme measures to hide the condition and, indeed, often refuse to admit
to any problem. Diagnosis relies on a medical history, clinical investigation