Pocketbook of Differential Diagnosis

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Thrombocytosis is a high platelet count >400/450 × 10 9 It may be secondary to a myeloproliferative disorder or another pathological process. Causes You’re Reading a Preview Become a Clinical Tree membership for Full access and enjoy Unlimited articles…

Thrombocytopenia is a low platelet count below 150 × 10 9 The causes of a low platelet count can be grouped according to reduced production, decreased survival or sequestration in the spleen. Causes Reduced production ● Aplastic anaemia ●…

Polycythaemia is an increase in red cell concentration above the normal limit, usually accompanied by a corresponding increase in haematocrit and haemoglobin concentration. Polycythaemia can be ‘real’ due to a true increase in red cell concentration or ‘apparent’ due to…

Leucopenia is a reduction in circulating white blood cells. The normal range is 4–11 × 10 9 In practice, the commonest form is neutropenia – a deficiency of neutrophil granulocytes. Neutropenia may be selective or part of a pancytopenia.…

Leucocytosis is an increase in the absolute count of circulating white blood cells. The normal range is 4–11 × 10 9 It may involve any of the types of white cells, but a polymorphonuclear leucocytosis, i.e. neutrophilia, is the…

Disorders of clotting can present with an increased tendency to clotting (thrombophilia) or a decreased ability to form clots and therefore an increased risk of bleeding. Causes Increased clotting Congenital ● Factor V Leiden deficiency ● Protein C deficiency ●…

Anaemia is defined as a haemoglobin concentration of <13.5 g/dL in men and <11.5 g/dL in women. Classification of anaemia according to red cell indices is useful because specific investigations can be tailored accordingly. Causes Microcytic (MCV <80 fL) ●…

Blood urea is a useful test of renal function. However, other factors such as liver failure, dehydration and protein breakdown may alter levels of blood urea. The normal level of blood urea is 2.5–7.8 mmol However, values may be lower…

Respiratory alkalosis is a common disorder in critically ill patients. It occurs when carbon dioxide is lost via excessive pulmonary ventilation (↑ pH, ↓ p CO 2 ). Compensatory mechanisms are: ■ ↓ HCO 3 − by bicarbonate buffer system…