Anaemia



ANAEMIA

“The Anaemic Lady”, Samuel van Hoogstraten, oil on canvas 1669, Rijksmuseum, Amsterdam.

ANAEMIA

Introduction

On blood film anemia can be classified into 3 types:

1. Hypochromic Microcytic.

2. Macrocytic.

3. Normchromic Normocytic.

Causes

Hyprochromic Microcytic Anaemia

There are 4 types:

1. Iron deficiency

2. Sideroblastic

3. Thalassemia

4. Anemia of chronic disease (if severe, however, this is more usually normochromic normocytic)

Macrocytic Anemia

There are 2 types:

1. Macrocytic Anemia with increased reticulocytes:

● Recent hemorrhage.

● Hemolysis.

● Response to treatment (eg. Iron or B12)

2. Macrocytic Anemia with decreased reticulocytes:

● B12 Deficiency

● Folate Deficiency

● Alcohol Abuse

● Cytotoxic agents.

Normochromic Normocytic Anaemia

There are 2 types:

1. Normochromic normocytic anaemia with increased reticulocytes

● Recent Hemorrhage

● Hemolysis

● Response to treatment

2. Normochromic normocytic anaemia with decreased reticulocytes

● Anemia of chronic disease

● Failure of bone marrow.

● Dilutional

Causes of Marrow Failure

1. Idiopathic, aplastic anemias.

2. Infiltrative

● Hematological

● Non-hematological

● Metastasis

3. Drugs (including idiosyncratic reactions such as chloramphenicol), chemicals, toxins

4. Nutritional:

● Severe folate deficiency.

● B12 deficiencies

5. Infection, especially viral

6. Radiation

7. Chronic renal failure.

8. Endocrinopathies, (cortisol / thyroxin deficiency)

Causes of Hemolysis

There are 2 types:

● Coombs negative, (non antibody induced)

● Coombs positive, (antibody induced)

Causes of Coombs negative Hemolysis:

Intracorpuscular Congenital Defects:

1. Membrane defects

● Spherocytosis

● Elliptocytosis

● Paroxysmal nocturnal Hb uria (a membrane defect)

2. Hb defects

● Sickle cell anemia

● Thalassemia

3. Enzyme defects

● G-6-P-D deficiency.

Extra-corpuscular:

1. Hypersplenism.

2. Mechanical:

● “March”

● Prosthetic valves

3. Osmotic

4. Direct toxin/chemical

5. Burns

6. Infection:

● Septicemia in general.

● Malaria

7. Micro-angiopathic hemolytic anemias (intravascular hemolysis in association with micro vascular pathology), such as:

● TTP

● HUS

● DIC

● Malignancies

● Vasculitic conditions

Causes of Coombs Positive Hemolysis

Warm reactive Abs, (37( C, IgG):

1. Primary idiopathic

2. Secondary:

● Malignancy, (especially CLL, lymphoma)

● SLE

● Drugs, (hapten induced)

Cold reactive Abs, (< 32(C, IgM):

1. Primary, often elderly with Raynauds disease.

2. Secondary

● Infection, viral, mycoplasma

● Lymphomas, rarely.

Investigations

Hypochromic Microcytic Investigations

To differentiate the 4 hypochromic microcytic conditions:

| | | | |

|Type |Fe Levels |Transferrin |Ferritin (Serum) |

| | | | |

|Iron deficiency Anemia |( |N or ( |( |

| | | | |

| | | | |

|Anemia of Chromic Disease |( |( |N or ( |

| | | | |

| | | | |

| | | | |

| | | | |

|Thalassemia |N |N |N |

| | | | |

|Sideroblastic |( |N |N or ( |

Reticulocyte Counts

When looking at a reticulocytosis the patient’s Hb level must be taken into consideration.

Hb/Normal Hb x % reticulocytes

eg. 5/15 x 7%

( 2 1/3 % (normal value is 0.2 – 2.0%)

Tests for Hemolysis

● Increased reticulocyte count

● Increased unconjugated bilirubin

● Decreased serum haptoglobin

● Increased LDH

● Hb uria

Coombs testing

● If hemolysis is suspected then a coombs test should be ordered to help determine whether the cause of the hemolysis is antibody mediated.

Blood Film Morphology Examination

This is important for determining the diagnosis in many cases.

Features that are looked for include:

1. RBC morphology

2. White cell counts and morphology

3. Platelet counts and morphology

4. Reticulocyte count.

Bone Marrow Biopsy

This will often be necessary to determine the cause of bone marrow failure.

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