Anemia is defined as the condition where the haemoglobin concentration in blood is below the lower limit of the normal range for that particular age or sex of the individual. For adults, the lower limit of haemoglobin concentration is given by, 11.5 g/dl for females and 13.0 g/dl for makes. New born infants have a higher haemoglobin level as their lower limit d 15.0 g/dl. For a 3 month old, the lower limit id 9.5 g/dl.

Pathophysiology of anemia

Low amounts of haemoglobin in the blood reduce the blood’s capacity to carry oxygen, which in turn results in compensatory physiological reactions including.

  • Increased oxygen release from haemoglobin.
  • Increasing tissue blood flow.
  • Maintaining blood volume constant.
  • Blood flow is redirected to maintain the supply of blood to the brain

Clinical features of anemia

The signs and symptoms of anemia depends on 4 main factors,

  • Speed of onset of anemia.
  • Severity of anaemia.
  • Age of the patient.
  • Haemoglobin dissociation curve


The symptoms of anemia are given by,

  • Tiredness
  • Fatigue
  • Muscular weakness
  • Headache
  • Lethargy

While the symptoms in older subjects are,

  • Cardiac failure
  • Angina pectoris
  • Intermittent claudication
  • Visual disturbances
  • Confusion

Types of anemia

Types of anemia

Signs of anemia

Even though there are different types of anemia, the following signs are common too all types of anemias

1. Pallor- Visible in the skin, conjunctivae, and mucous membranes.

2. Condition of the cardiovascular system. Tachycardia, a collapsing pulse, cardiomegaly, a midsystolic flow murmur, dyspnea with exertion, and congestive heart failure in the elderly are all signs of a hyperdynamic circulation.

3. Central nervous system: Older patients may experience CNS-related symptoms such as episodes of dizziness, fainting, headaches, tinnitus, sleepiness, and numbness and tingling in the hands and feet.

4. Ocular manifestations: If there is a vascular disease or bleeding disorder present, retinal haemorrhages may happen.

5. Reproductive system: Menstrual irregularities including amenorrhoea and menorrhagia, as well as libido loss, are some of the reproductive system’s symptoms in anaemic people.

6. Renal system: Severe anaemia may cause mild proteinuria and reduced kidney concentrating ability.

7. The digestive system may result in anorexia, flatulence, nausea, constipation, and weight loss.

Types of anemia

The different types of anemia can be illustrated using the below flow chart


Our body has 3 to 5 grams of iron in the blood while 50% to 75% of them are carried by the haemoglobins. Deficiency in iron cause iron deficiency anemia or nutritional anemia.


  • Lack of iron in the diet
  • Loss of blood
  • Pregnancy
  • Inability to absorb iron from the food

Pathophysiology of IDA

Clinical features

  • Fatigue, irritability, palpitations, dizziness, breathlessness, headache
  • Abnormalities in muscle metabolism
  • Numbness and tingling
  • Impairment of neurological development in infants

Treatment of IDA

Treatment of IDA is done through the following methods.

  • Oral or parental iron preparation
  • Using oral ferrous salts


This type of anemia is caused due to the deficiency of cobalamin, folate or when a subject undergoes therapy with anti folate drugs and drugs interfering with the synthesis of DNA.

Pathogenesis of Megaloblastic anemia

Clinical features

  • Weight loss
  • Altered skin pigmentation
  • Depression
  • Poor memory
  • Personality change
  • Breathlessness
  • Visual disturbance

Treatment of megaloblastic anemia

  • Treating b12 deficiency: this can be done by vitamin therapy or intramuscular/subcutaneous injections
  • Treating folate deficiency: This can be done through vitamin therapy


This is caused due to,

• Stressors including infections, medications, snake or spider venom, or particular diets. • Inherited diseases like sickle cell anaemia and thalassemia.

• Toxins caused by chronic renal or liver illness.

• An immune system attack that isn’t necessary.

• Vascular grafts, artificial heart valves, malignancies, severe burns, chemical exposure, extreme hypertension, and clotting abnormalities.

• A seldom occurring enlarged spleen.

Pathogenesis of haemolytic anemia

Clinical features

1. The mucous membranes are paler.

2. In patients with congenital hemolytic anaemia, a positive family history is associated with lifelong anaemia.

3. Mild hyperbilirubinemia without conjugation that causes intermittent jaundice.

4. An overabundance of urobilinogen in urine causes urine to turn black when standing.

5. The majority of acquired and congenital chronic hemolytic anemias exhibit splenomegaly.

6. In some circumstances, pigment gallstones are discovered.


  • Corticosteroids
  • Blood transfusion
  • Splenectomy
  • Immunosuppressive drugs


For the absorption of vitamin B12 in the stomach, intrinsic factor(IF) is essential. Due to the deficiency of this intrinsic factor, the stomach can’t absorb enough vitamin B12 which leads to permanent damage to nerves and other organs. Thus pernicious anemia is caused.


Clinical features

  • Anemia
  • Numbness
  • Tingling
  • Ataxia
  • Weight loss


Treatment is done by making the patient take vitamin B12 supplements and eating foods that have high folic acid and B12 content.

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