Biology of Disease

(Table 13.4). The transferrin saturation, that is the proportion of serum iron

to its total iron binding capacity, falls below 19%, compared with a more

usual 30% or so. The concentration of serum ferritin resulting from cellular

degradation is regarded as the most reliable measurement of anemia. Patients

may also show an impaired ability to maintain body temperature, depressed

muscle function and abnormal thyroid hormone metabolism.

The underlying cause of the iron deficiency should be identified by the

appropriate tests and taking a careful history of the patient. To counteract

the deficiency, 600 mg of ferrous sulfate is given orally each day. If there are

side effects, such as nausea, diarrhea or constipation, then ferrous gluconate

may be substituted. Failure to respond to the treatment may be due to lack

of patient compliance, continuing hemorrhage, severe malabsorption, or

another cause for the anemia. It may be necessary to give iron parentally if

absorption is defective, as for example in patients with ulcerative colitis or

Crohn’s disease (Chapter 11).

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Figure 13.15 An automated blood analysis

system that can determine all hematological

indices automatically. Courtesy of Department of

Clinical Biochemistry, Manchester Royal Infirmary,

UK.

Figure 13.16 A photomicrograph of a peripheral

blood smear from a patient suffering from severe

iron deficiency. The cells are microcytic and

hypochromic.

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