Anemia

Iron sources: The normal Western diet contains ~10-20mg of iron per day; most in haeme contained in animal products (meat, fish & eggs) and remainder in inorganic iron in vegetables (spinach etc)

Iron absorption:

Iron is absorbed as haeme and Fe²⁺ (not Fe³⁺); the duodenum (2^nd upper jejunum) is the primary site of absorption. About 20% of haeme iron (in contrast to 1-2% of non-haeme iron) is absorbable; iron in many foods is unavailable because it is in complex form with phytates or phosphates.

Bioavailability is important and affected by…

Acidic pH of stomach is reductive (Fe³⁺ + e^-  Fe²⁺) - facilitating absorption of the iron. Antacids instead, facilitates oxidation to Fe³⁺ and formation of non-absorbable complexes (e.g. some antibiotics - tetracycline) hence limiting absorption of the iron.

Other dietary ingredients may influence absorption also:

• Ascorbic acid increases absorption (in oranges)

• Tannic acid decreases absorption (in tea)

Daily requirements:

• Men & postmenopausal women: 1mg/day

• Pregnancy: 3mg/day

• Child: 1.5mg/day

• Menstruating women: 2mg/day

[Clinical features of iron deficiency include spoon nail, angular cheilitis, pica and anaemia]

Diagnosis: rests on clinical and haematological features…

Take history (diet, medication, blood loss) and examine for other clinical signs and symptoms of anaemia (fatigue, headache, syncope, hypotension, tachycardia etc).

Negative iron balance and consequent anaemia may result from low dietary intake (rare in developed countries), malabsorption (sprue and celiac disease or gastrectomy), excessive demand (pregnancy & infancy), and chronic blood loss.

Chronic blood loss is the most important cause of iron deficiency anaemia in the Western world; this loss may occur from the GIT (e.g. peptic ulcers, colonic cancer, haemorrhoids, hookworm disease) or the female genital tract (e.g. menorrhagia, metrorrhagia, cancers). If this is to be the case, then treat underlying cause or consider specialist referral.

Low body iron load would be reflected in low serum iron and ferritin   transferrin synthesis (GIT) to facilitate absorption ( total plasma iron-binding capacity and  plasma transferrin saturation). Thus both serum ferritin and transferrin would have to be tested for diagnosis of iron deficiency.

Note: Diagnostic trial of oral iron therapy may be appropriate ( Hb is diagnostic).

Further tests and investigations include:

• Full blood count

• Urea, electrolytes and liver function tests

• Midstream urine

• Faecal occult blood tests

• GI tract visualization (endoscopy or barium)

• Consider specialist referral

Treatment: Treat underlying cause, iron supplements or specialist referral.

Category: Medicine Notes