A 45-year-old Singaporean man presents to the GP with lethargy for the…
A 45-year-old Singaporean man presents to the GP with lethargy for the last few months. The GP did a full blood count which shows that the patient is anaemic.
RBC production defect (Normal or low reticulocytes)
Normocytic (Proliferation disorder)
Malignant and premalignant: e.g. bone marrow
infiltration by leukemia, myeloma, myelofibrosis.
Look for constitutional sym, hepatosplenomegaly,
and ‘CRAB’ symptoms of myeloma (hyperCa, renal
impairment, anaemia, and bone pain)
Primary aplastic anemia: often acquired autoimmune cause,
sometimes genetic (e.g. Fanconi anemia)
Secondary aplastic anemia: due to drugs (e.g. chemotherapy,
carbimazole), toxins (e.g. benzene), radiation
etc. Viruses (e.g. parvovirus, hepatitis, HIV)
can cause transient anemia or pancytopenia.
Ask about relevant exposures.
: diseased kidneys do not synthesize
sufficient erythropoietin, causing anemia
Anemia of chronic dx (AoCD)
anaemia is due to inadequate erythropoiesis and ↓
RBC survival. Ask about chronic inflammatory
states e.g. infection, RA, cancer
Myelodysplastic syn: ↓ Hb is an early presentation
Isolated red cell aplasia
Macrocytic (RBC synthesis defect)
Megaloblastic anemia (B12 or folate deficiency)
GIT dx: gastrectomy (↓ intrinsic factor prod), ileal
resection/dx (↓ B12 absorption),
Gastritis, Gastric or duodenal ulcer
Drug: methotrexate, phenytoin, trimethoprim, etc
inhibit folate metabolism, so take a full drug hx.
Pernicious anemia: autoimmune destruction of
parietal cells, ↓ intrinsic factor, ↓ B12 absorption.
Diet: dietary deficiency of B12 is uncommon except
in vegans (no B12), but folate deficiency is common
in the malnourished.
Physiological: pregnancy, newborn
Pathological: Alcoholism (most common),
drugs (e.g. azathioprine),
Microcytic (Hb synthesis defect)
Iron deficiency (common)
. There may be physical
signs of koilonychia or angular chelitis. This is not a
diagnosis but should prompt a search for the cause
Thalessemia: genetic defects in Hb synthesis (see
hemolysis). In particular, thalassemia minor is
asymptomatic except for mild microcytic anemia.
Reticulocytes may be normal or ↑.
Sideroblastic anemia: ineffective heme synthesis,
either inherited or acquired, in which case it is often
due to myelodysplasia.
Anemia of chronic dx
: usually normocytic, but
may present as microcytic anemia as inflammation
↑ hepcidin, inhibiting iron absorption.
RBC destruction or loss (↑ Reticulocytes (>2.5%))
Enzyme: G6PD deficiency in males. Presents with
acute hemolytic episodes, precipitated by infection,
drugs (e.g. antimalarials, antibiotics, analgesics), fava
beans. Blood count is normal between episodes.
Cytoskeletal: e.g. hereditary spherocytosis, elliptosis,
Haemoglobin: Thalassemia (α, β, or HbE-β), or
sickle cell anemia
, esp african-americans. Hemolysis
is rarely prominent in thalassemia, but there is often
Autoimmune hemolytic anemia (AIHA)
common cause, confirmed by +ve direct Coomb’s
Microangiopathic hemolytic anemia: hemolytic
picture with schistocytes and –ve Coomb’s test, e.g.
DIC, HUS, TTP (see approach to bleeding)
Malaria: esp Plasmodium falciparum infection. Ask
abt fever, travel hx, use of prophylaxis. Do thick
and thin blood films for diagnosis.
Fragile RBCs easily lysed: e.g. B12 deficiency
Mechanical hemolysis e.g. prosthetic valves
Hypersplenism: accept only as a cause of mild
anemia; if severe anemia develops in a patient with
portal hypertension suspect variceal bleeding.
Acute: Hb and HCt are initially normal, as whole
blood (including plasma) is lost.
Subacute (hours): the body (or doctors) replaces
lost plasma, causing ↓ hematocrit. There is relative
↓ RBCs as erythropoiesis takes a week, giving what
appears to be normocytic anemia.
Compensated: as erythropoiesis kicks in, there is ↑
reticulocytes, reflecting normal marrow response to
anemia. Without further blood loss, the normocytic
anemia will correct itself.
Chronic blood loss more commonly presents as
iron-deficiency anemia than as ↑ RBC production.
Reticulocytes ↓, reflecting inadequate erythropoietic
factors. This should prompt a search for a cause –
occult blood loss in an elderly patient may be the
first presentation of
jaundice, pallor, peripheral cyanosis, dyspnoea, splenomegaly