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Anemia is the presence of reduced hemoglobin in the blood. Formally, the World Health Organization (WHO) defines anemia by the hemoglobin concentration in the blood according to age and sex 1: adult men: <130 g/L adult women: <120 g/L Values for pregnant women and children are different. Pat...

Anaplastic lymphoma kinase (ALK) gene rearrangements

Anaplastic lymphoma kinase (ALK) gene rearrangements are known to occur in association with several tumors. The genes codes for an enzyme called anaplastic lymphoma kinase (ALK) or ALK tyrosine kinase receptor / CD246 which is thought o play a role in the brain development and exerts its effects...


Blood is a connective tissue; it comprises a fluid component called plasma (about 55% of the total volume), in which lies the cellular component, comprising several cell lineages, primarily the white blood cells, red blood cells and platelets. In an average adult male the total volume of blood i...


CD34 or hematopoietic progenitor cell antigen CD34 is an intercellular adhesion protein and cell surface glycoprotein and a frequently used marker of hematopoietic progenitor cells and endothelial cells. It is also expressed by many other non-hematopoietic cell types including multipotent mesenc...


Eosinophils, also less commonly known as acidophils, are myeloid granulocytes and form one of the main types of white blood cells. Their counts are routinely measured as part of a full blood count. They have important roles in fighting parasitic infections, but are increasingly recognized as hav...


Eosinophilia is defined as an abnormally high level of eosinophils in the blood, this is usually defined as >500 cells/μL (normal eosinophil level: <450 cells/μL). Hypereosinophilia is defined as >1500 cells/μL and is usually due to hematological malignancy 1,2. This article includes recommenda...

Erythrocyte sedimentation rate

Erythrocyte sedimentation rate (ESR) is a non-specific marker of acute inflammation which is seen in a very wide spectrum of pathologies. In recent years it has been sidelined by the use of C-reactive protein and other acute phase markers but it still has an important role to play in the managem...

Extranodal extension

Extranodal extension refers to the growth of a nodal cancer metastasis beyond the confines of the capsule of a lymph node into adjacent tissues. Less preferred synonyms include extranodal spread, extracapsular extension, or extracapsular spread. This finding holds prognostic implications. For e...


The hematinics are nutrients that are required by the body for erythropoiesis, i.e. the production of red blood cells 1,2. List of hematinics Clinically, the most important hematinics are vitamin B12, iron and folic acid because deficiency states of these three substances are much more common ...


Hemoglobin (Hb) is the oxygen-carrying molecule in red blood cells. Structure Hemoglobin is a tetrameric protein molecule composed of four subunits. Each subunit consists of an iron-containing cyclic heme component linked to a polypeptide chain, the polypeptides are together known as globin. E...

Hypersensitivity reaction

Hypersensitivity reactions are the immunological response to both exogenous and endogenous antigens, and form the basis for many diseases.  Pathology Classification Using the Gell and Coombs' classification, there are four types of hypersensitivity reactions, each mediated by a different mech...


The human body regularly encounters harmful microorganisms, and because of this it has developed a system of defenses to help identify and eliminate infective pathogens in the body, known as the immune system. Humans have two types of immunity: innate immunity and acquired immunity. innate imm...


Iron (chemical symbol Fe) is one of the trace elements that is essential for normal human health due to its central importance in the structure and function of hemoglobin and the cytochromes. Chemistry Basic chemistry Iron is a transition metal with atomic number 26 and an atomic weight of 55...

Lactate dehydrogenase

Lactate dehydrogenase (LDH or LD) is a key enzyme in most cells, catalyzing the reversible conversion of pyruvate to L-lactate. Its contemporaneous main clinical uses are limited primarily to the investigation of hemolysis, serous collections and as a tumor marker. Physiology L-lactate dehydro...

Red blood cell

Red blood cells (RBCs), also known as erythrocytes (or haematids), are "cells" that carry oxygen by means of hemoglobin, and form part of the cellular component of blood as it circulates throughout the body. These extremely common cells are typically made in the bone marrow in a process called e...

Reed-Sternberg cells

Reed-Sternberg cells are a classical finding diagnostic of Hodgkin lymphoma. They are giant, multinucleated cells with abundant pale cytoplasm. Reed-Sternberg cells are rare, making up <1% of lymphoid tissue, with the background consisting of lymphocytes, plasma cells, eosinophils and macrophages.

Vitamin K

Vitamin K is not a single compound but a family of fat-soluble vitamins essential for normal blood-clotting function and comprises two vitamers that are found naturally: phytomenadione (also known as phylloquinone or K1) and menaquinone (or K2). Menaquinone (K2) is synthesized by normal flora i...

White blood cell

White blood cells or leukocytes are one of the main cell types found in normal human blood. They are actually colourless (but appear white on light microscopy) and are divided into granular and non-granular types. Types of white blood cell: granular neutrophils eosinophils basophils non-gr...

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