Iron Deficiency Anemia & Nutritional Anemia

Exam Written Answer

1. DEFINITION & OVERVIEW

2. CAUSES (ETIOLOGY)

A. Dietary Lack (Inadequate Intake)

• Most common cause in developing countries and children
• Infants are at high risk: human breast milk provides only ~0.3 mg/L of iron; cow's milk has ~twice as much but poor bioavailability
• Toddlers on exclusive cow's milk or poorly iron-supplemented diets
• Impoverished populations with inadequate meat intake
• Vegans (lack of heme iron)
• Older adults with restricted diets

B. Impaired Absorption

• Coeliac disease, tropical sprue, other malabsorption syndromes
• Chronic diarrhea
• Gastrectomy (reduced acid decreases Fe³⁺ → Fe²⁺ conversion; faster gastric emptying)
• Dietary inhibitors: tannins (tea), carbonates, oxalates, phosphates, phytates

C. Increased Requirement

• Growing infants, children, and adolescents
• Pregnancy (the single greatest physiological demand)
• Premenopausal females (menstrual losses of ~30 mg/cycle)
• Multiple, closely spaced pregnancies

D. Chronic Blood Loss (Most Common Cause in Adults in Developed Countries)

• GI bleeding: peptic ulcer, carcinoma, hookworm infestation, hemorrhoids, inflammatory bowel disease - must be excluded in adult males and postmenopausal females before attributing IDA to any other cause
• Menorrhagia: heavy menstrual bleeding
• Urinary losses: haematuria, haemoglobinuria
• Parasitic infestation: hookworm is a major cause worldwide

3. PATHOGENESIS (STAGES OF IRON DEPLETION)

4. CLINICAL FEATURES

General Features of Anemia (Any Cause):

• Pallor (skin, conjunctivae, nail beds, palmar creases)
• Easy fatigability, lethargy, weakness
• Dyspnea on exertion
• Palpitations, tachycardia
• Headache, dizziness, poor concentration

Features Specific to Iron Deficiency (due to depletion of iron-containing enzymes):

In Children Specifically:

• Anorexia
• Recurrent infections (impaired cell-mediated immunity)
• Behavioral disturbances, poor school performance
• Irritability, decreased activity

5. LABORATORY INVESTIGATIONS

A. Complete Blood Count (CBC) / RBC Indices

B. Peripheral Blood Smear - KEY FINDINGS

1. Microcytosis - small RBCs (diameter < 6 µm)
2. Hypochromia - enlarged zone of central pallor (normal = 1/3 of cell diameter; in IDA, pallor occupies > 1/3, with hemoglobin seen only as a thin peripheral rim)
3. Anisocytosis - variation in cell size (reflected by elevated RDW)
4. Poikilocytosis - variation in cell shape
5. Pencil cells (cigar cells) - small, elongated, elliptical red cells - characteristic of IDA
6. Target cells - occasionally seen
7. Hypersegmented neutrophils - NOT seen in IDA (this feature suggests megaloblastic anemia)

C. Iron Studies (Diagnostic)

Serum ferritin is the single most sensitive and specific non-invasive test for IDA. A ferritin < 12 µg/L is virtually diagnostic. However, ferritin is an acute-phase reactant and may be falsely elevated in inflammatory states.

D. Bone Marrow Examination (Gold Standard, rarely needed)

• Mild-to-moderate increase in erythroid progenitors (erythroid hyperplasia)
• Absence of stainable iron in macrophages on Prussian blue (potassium ferrocyanide) stain - this is the diagnostic gold standard
• Ringed sideroblasts absent (unlike sideroblastic anemia)

E. Additional Tests

• Reticulocyte count: Baseline low; rises (reticulocytosis) within 5-7 days of starting iron therapy - confirms the diagnosis therapeutically
• Stool for occult blood: To identify GI bleeding source
• Stool for ova and parasites: To rule out hookworm

F. Nutritional Anemia Lab Summary (Katzung)

6. TREATMENT

A. General Principles

1. Treat the underlying cause (e.g., deworm for hookworm, treat bleeding lesions)
2. Dietary correction (iron-rich foods: meat, poultry, fish, legumes, green leafy vegetables, fortified cereals)
3. Iron supplementation - oral is preferred in most cases
4. Vitamin C (ascorbic acid) enhances non-heme iron absorption - give simultaneously

B. Oral Iron Therapy

• Ferrous sulfate, ferrous gluconate, ferrous fumarate - all effective and inexpensive

C. Oral Iron Therapy in a 2-Year-Old Child

• Therapeutic dose: 3-6 mg/kg/day of elemental iron, divided into 2-3 doses per day
• For a 2-year-old (average weight ~12 kg): approximately 36-72 mg elemental iron/day

• Give on an empty stomach (1 hour before or 2 hours after meals) for maximum absorption
• If GI side effects (nausea, vomiting, constipation) occur, can be given with small amounts of food - but avoid milk/dairy simultaneously
• Give with orange juice or vitamin C to enhance absorption
• Avoid concurrent milk intake (calcium inhibits iron absorption)
• Avoid tea (tannins inhibit absorption)
• Duration: Continue for 3 months after hemoglobin normalizes to replenish iron stores (total treatment typically 4-6 months)
• A reticulocyte response (reticulocytosis) within 5-7 days and a rise in Hb of ≥ 1 g/dL by 4 weeks confirms the diagnosis and adequate response
• If no response: check compliance, consider malabsorption, recheck diagnosis

D. Parenteral Iron Therapy

• Failure or intolerance of oral iron
• Malabsorption (e.g., inflammatory bowel disease, after gastrectomy)
• Very severe anemia requiring rapid repletion
• Non-compliance with oral therapy
• Chronic kidney disease patients on erythropoietin

E. Blood Transfusion

• Severe symptomatic anemia (Hb < 5-6 g/dL)
• Cardiac decompensation
• Active severe bleeding
• Pre-operative correction when urgent

F. Dietary Advice

• Heme iron (better absorbed, ~20%): Red meat, poultry, fish, liver
• Non-heme iron (1-5% absorbed): Legumes, spinach, lentils, iron-fortified cereals, dried fruits, jaggery
• Avoid tea/coffee with meals; take vitamin C-rich foods with meals

7. MONITORING RESPONSE TO TREATMENT

KEY EXAM MNEMONICS

• Dietary deficiency
• Impaired absorption
• Augmented requirement
• Loss of blood (chronic)

• Koilonychia
• Angular stomatitis / Alopecia
• Glossitis
• Splenomegaly (mild)
• Pica
• Plummer-Vinson syndrome

• Microcytosis
• Hypochromia (enlarged central pallor)
• Anisocytosis (increased RDW)
• Poikilocytosis
• Pencil cells (pathognomonic)