Changes in complete blood count parameters influenced by endocrine disorders

Complete blood count is one of the most common diagnostic methods used in everyday practice. Hormonal status is known to affect blood count parameters. The aim of this study is to summarize changes in blood count that may indicate endocrine disorders, based on a literature review. Red cell parameters deteriorate in thyroid disorders including autoimmune thyroiditis and tend to resolve with appropriate treatment implementation. The most frequent form of anaemia associated with thyroid dysfunction is normocytic anaemia. Macrocytic anaemia is more typical of autoimmune thyroiditis-induced hypothyroidism, while microcytic anaemia is more common in hyperthyroidism. Unexplained anaemia or an increase in red cell distribution width should prompt the investigation of thyroid disorders. Cushing's disease may manifest as an increase in white blood cells and platelets. In the blood smear, neutrophilia is often present, while lymphocytes and eosinophils may be within the lower normal range. Hypercortisolism may induce both hyperaemia and anaemia. In hypopituitarism, a decrease in red blood cell count, haemoglobin, haematocrit, and platelets is observed. Acromegaly may be accompanied by an increase in mean corpuscular volume of erythrocytes. Testosterone deficiency is manifested by a decrease in red cell parameters, whereas hyperandrogenism may lead to polycythaemia. In polycystic ovary syndrome an increase in white blood cell count reflects an underlying inflammatory state. Complete blood count analysis is an easily available and cost-effective additional tool in the diagnosis and treatment monitoring of endocrine disorders.