Blood Disease: Understanding Anemia

Presenting Problems in Blood Disease

• Anemia is a condition where hemoglobin levels fall below the normal range for age and sex.
• Factors like pregnancy (increased plasma volume) and altitude affect hemoglobin levels.
• Pregnancy lowers the reference range for normal hemoglobin to above 105 g/L at 28 weeks.
• Mean cell volume (MCV) may increase by 5 fL in pregnancy.
• Gestational thrombocytopenia (low platelet count) is a usually benign condition.
• Altitude also affects hemoglobin levels; this must be considered when assessing anemia.

Learning Objectives

• Define, classify, and identify causes of anemia.
• Describe the clinical presentation of anemia.
• Outline the investigation and approach to diagnosing anemia.
• Identify causes of iron deficiency anemia (IDA), investigate, and diagnose.
• Explain iron absorption, regulation, and distribution in the body.
• Differentiate between anemia diagnosis and treatment.

Clinical Features of Anemia

• Clinical features of anemia reflect diminished oxygen supply to tissues.
• They depend on the degree of anemia, the speed of development.
• The presence of cardio-respiratory disease influences anemia symptoms.
• Rapid onset anemia (like blood loss) results in more pronounced symptoms than gradually developing anemia.

History

• Iron deficiency anemia is the most common global anemia type.
• Thorough gastrointestinal (GI) history is needed, looking for blood loss symptoms.
• Menorrhagia (heavy menstrual bleeding) is a common cause of anemia in menstruating women.
• Dietary history must assess iron and folate intake, especially in pregnancy and rapid growth periods.

Past, Family, and Drug History

• Past medical history may reveal conditions linked to anemia (e.g., rheumatoid arthritis, GI surgery).
• Family history can suggest hereditary anemias (e.g., hemoglobinopathies, spherocytosis).
• Drug history can identify medications that may cause blood loss or hemolysis.

Physical Examination

• General physical exam findings for anemia are supplemented with findings related to the cause.
• Example: Right iliac fossa mass suggests potential cancer.
• Associated conditions might include jaundice (hemolytic anemia), neurological signs (vitamin B12 deficiency), and leg ulcers (sickle-cell anemia).
• Absence of specific symptoms doesn't rule out undiagnosed pathology.

Causes of Anemia:

• Decreased or ineffective marrow production.
  • Lack of iron, vitamin B12, or folate
  • Hypoplasia
  • Malignant cell invasion
  • Renal failure
• Peripheral causes.
  • Blood loss
  • Haemolysis
  • Hypersplenism

Investigation of Anemia

• Anemia investigation often relies on red blood cell size (MCV).
• Low MCV suggests iron deficiency or thalassemia.
• High MCV suggests vitamin B12 or folate deficiency.
• Normal MCV might indicate acute blood loss or anemia of chronic disease.
• The reticulocyte count differentiates between red blood cell production failure and increased destruction.

Iron Deficiency Anemia: Prevalence

• Approximately 30% of the global population has anemia, with half experiencing iron deficiency anemia.

Iron Importance

• Iron is crucial for fundamental processes, including oxygen and electron transport and respiration.
• Iron-containing heme proteins are essential, including hemoglobin, myoglobin, cytochromes, peroxidases, and catalase.
• Many Kreb cycle factors contain or depend on Iron.

Iron Absorption

• Normal mixed diets offer 10-20 mg of daily iron.
• Iron exists in inorganic or organic forms (e.g., meat, vegetables, beans, milk is low in iron).
• Only 5-10% of ingested iron is absorbed.
• Iron is released from protein compounds by stomach acid and enzymes in the small intestine.
• Duodenum and jejunum are the primary absorption sites.

Iron Absorption Regulation

• Intestinal mucosal cells regulate iron uptake.
• Body iron stores influence mucosal iron.
  • High stores prevent absorption.
  • Low stores promote absorption.
• Mucosal cells shed into the lumen when iron stores are high.

Iron Excretion

• No physiological iron excretion pathway.
• Iron loss happens via:
  • Intestinal cell shedding
  • Urine
  • Nails, hair shedding
  • Menstruation
• Daily losses (~1 mg) are compensated by absorption.

Iron Distribution in the Body

• Total body iron ranges from 3.5 to 2.5 g.
• Most is in hemoglobin (~65-70%).
• Storage iron includes ferritin and hemosiderin within reticuloendothelial systems (bone marrow, spleen, liver) and also in liver cells.
• Tissue iron is found in iron-containing enzymes and myoglobin.
• Plasma iron is a small fraction (~0.1%) delivered by transferrin to tissues.

Iron Deficiency Anemia: Blood Loss

• Gastrointestinal (GI) blood loss is the common explanation in men and post-menopausal women.
• This includes occult cancers, gastritis, ulcers, inflammatory bowel disease.
• Hookworm and schistosomiasis are prevalent causes in developing countries for GI blood loss.
• Chronic NSAID use exacerbates GI blood loss.

Iron Deficiency Anemia: Other Causes

• Menstruation, pregnancy, and breastfeeding lead to increased iron needs and decreased stores, especially in women.
• Poor dietary iron intake, especially in developing countries, is another major cause during infancy, pregnancy, and adolescence.
• Malabsorption (e.g., celiac disease) impedes iron absorption.

Iron Deficiency Anemia: Investigations

• Plasma ferritin is vital for confirming iron deficiency.
• Subnormal ferritin levels indicate deficiency; however, raised ferritin might exist in liver disease or acute inflammation.
• Plasma iron and total iron-binding capacity (TIBC) measure iron availability and are influenced by multiple factors beyond iron stores.
• Transferrin levels are lowered by malnutrition and raised by pregnancy.
• Transferrin saturation (% of TIBC occupied by iron) is less specific but can suggest deficiency.
• Bone marrow aspirate and staining are diagnostic in complex cases.

Iron Deficiency Anemia: Investigation of Cause

• Investigating the causes depends on patient's age, sex, and symptoms.
• Men over 40/post-menopausal women with normal conditions need upper/lower GI tract endoscopy or barium studies.
• Coeliac disease suspicion warrants antigliadin/anti-endomysium antibody tests and duodenal biopsy.
• Stool and urine analyses are useful in tropical regions to check for parasites.

Iron Deficiency Anemia: Clinical Findings

• Early anemia presents without obvious findings.
• As anemia progresses, symptoms emerge like:
  • Pallor
  • Fatigue
  • Reduced exercise capacity
  • Shortness of breath
• Severe cases exhibit mucosal changes:
  • Mouth soreness (glossitis, smooth tongue).
  • Spooned nails (koilonychia)
  • Pica (unusual cravings).
• Organomegaly is unusual with IDA.

Iron Deficiency Anemia: Blood Picture

• Reduced hemoglobin and packed cell volume (PCV).
• Reduced mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and mean corpuscular hemoglobin concentration (MCHC).
• Leucocytes and platelets are usually normal.
• Peripheral blood film shows hypochromic, microcytic red blood cells.
• Bone marrow aspirate shows depleted iron stores.

Iron Deficiency Anemia: Diagnosis

• Diagnosing IDA involves evaluating hematologic parameters.
• Reduced serum iron.
• Increased total iron-binding capacity.
• Reduced transferrin saturation (S. iron/TIBC)
• Reduced serum ferritin.
• Bone marrow iron depletion (Prussian blue stain).

Iron Deficiency Anemia: Differential Diagnosis

• Other hypochromic anemias possible causes, such as thalassemia, sideroblastic anemia, lead poisoning, and chronic disease anemia are differentiated.
  • Thalassemia involves iron studies and haemoglobin electrophoresis
  • Sideroblastic anemia involves bone marrow iron staining.
  • Lead poisoning assesses history, blood film, and urine lead levels.
  • Chronic disease anemia involves iron studies.

Iron Deficiency Anemia: Management

• Oral ferrous sulphate (200 mg 8 hourly) is the primary therapy.
• Treatment duration is 3-6 months.
• Patients intolerant to ferrous sulfate can switch to ferrous gluconate.
• Parenteral iron (iron sorbitol) is needed only in cases of malabsorption or intolerance.
• Body weight and hemoglobin levels help estimate iron stores.
• Monitor haemoglobin levels, daily 7-10 days expected rise.

Iron Deficiency Anemia: Conclusion

• Comprehensive assessment and management for IDA address blood loss, nutritional deficiencies, and malabsorption.

This quiz explores the presenting problems associated with anemia, including its definitions, causes, and clinical features. Participants will learn to identify different types of anemia, such as iron deficiency anemia, and understand the factors influencing hemoglobin levels, particularly in pregnancy and at high altitudes.