The reduction of any or all of the three blood parameters reduces the oxygen-carrying capability of the blood, causing reduced oxygenation of body tissues, a condition called hypoxia.
Description All tissues in the human body need a regular supply of oxygen to stay healthy and perform their functions. RBCs contain Hgb, a protein pigment that allows the cells to carry oxygen (oxygenate) tissues throughout the body. RBCs live about 120 days and are normally replaced in an orderly way by the bone marrow, spleen, and liver.
As RBCs break down, they release Hgb into the blood stream, which is normally filtered out by the kidneys and excreted. The iron released from the RBCs is returned to the bone marrow to help create new cells.
Anemia develops when either blood loss, a slow-down in the production of new RBCs (erythropoiesis), or an increase in red cell destruction (hemolysis) causes significant reductions in RBCs, Hgb, iron levels, and the essential delivery of oxygen to body tissues.
Anemia can be mild, moderate, or severe enough to lead to life-threatening complications. More than 400 different types of anemia have been identified. Many of them are rare. Most are caused by ongoing or sudden blood loss.
Other causes include vitamin and mineral deficiencies, inherited conditions, and certain diseases that affect red cell production or destruction.
Anemia is the most common blood disorder, affecting about a third of the global population.
. On examination, the signs exhibited may include pallor (pale skin, lining mucosa, conjunctiva and nail beds), but this is not a reliable sign. There may be signs of specific causes of anemia, e.g., koilonychia (in iron deficiency), jaundice (when anemia results from abnormal break down of red blood cells — in hemolytic anemia),
Iron deficiency anaemia This occurs when iron losses or physiological requirements exceed absorption
Blood loss The most common explanation in men and postmenopausal women is gastrointestinal blood loss. This may result from occult gastric or colorectal malignancy, gastritis, peptic ulceration, inflammatory bowel disease, diverticulitis, polyps and angiodysplastic lesions.
Worldwide, hookworm and schistosomiasis are the most common causes of gut blood loss In women of child-bearing age, menstrual blood loss, pregnancy and breastfeeding contribute to iron deficiency by depleting
iron stores; in developed countries, one-third of premenopausal women have low iron stores but only 3% display iron-deficient haematopoiesis. Very rarely, chronic haemoptysis or haematuria may cause iron deficiency.
Malabsorption A dietary assessment should be made in all patients to ascertain their iron intake. Gastric acid is required to release iron from food and helps to keep iron in the soluble ferrous state Achlorhydria in the elderly or that due to drugs such as proton pump inhibitors may contribute to the lack of iron availability from the diet, as may previous gastric surgery.
Iron is absorbed actively in the upper small intestine and hence can be affected by coeliac disease
Investigations Confirmation of iron deficiency Plasma ferritin is a measure of iron stores in tissues and is the best single test to confirm iron deficiency
Plasma iron and total iron binding capacity (TIBC) are measures of iron availability; hence they are affected by many factors besides iron stores.
Investigation of the cause This will depend upon the age and sex of the patient, as well as the history and clinical findings. In men and in post-menopausal women with a normal diet, the upper and lower gastrointestinal tract should be investigated by endoscopy or radiological studies.
Serum antiendomysial or anti-transglutaminase antibodies and possibly a duodenal biopsy are indicated to detect coeliac disease. In the tropics, stool and urine should be examined for parasites
Management Unless the patient has angina, heart failure or evidence of cerebral hypoxia, transfusion is not necessary and oral iron replacement is appropriate.
Ferrous sulphate 200 mg 3 times daily is adequate and should be continued for 3–6 months to replete iron stores.
The haemoglobin should rise by around 10 g/L every 7–10 days and a reticulocyte response will be evident within a week. A failure to respond adequately may be due to non-compliance, continued blood loss, malabsorption or an incorrect diagnosis.,
Patients with malabsorption or chronic gut disease may need parenteral iron therapy. Previously, iron dextran or iron sucrose was used
but new preparations of iron isomaltose and iron carboxymaltose have fewer allergic effects and are preferred.