Category: Ha-Hf

Hemophagocytic lymphohistiocytosis (HLH) is a rare, cancer-like disorder in which certain types of immune system cells (histiocytes and lymphocytes) start to proliferate and damage body tissues or organs. It can be an inherited condition, or it can occur as a result of immunosuppression (as in organ transplants) or infection. Most patients are young children; signs and symptoms include Treatment is…

Known also as hereditary spherocytosis (HS), this is a genetic disorder of the red blood cell membrane clinically characterized by anemia, jaundice (yellowing) and splenomegaly (enlargement of the spleen). In HS the red cells are smaller, rounder, and more fragile than normal. The red cells have a spherical rather than the biconcave-disk shape of the normal red cell. These rotund red cells (spherocytes)…

Anemia due to the destruction, rather than underproduction, of red blood cells. Hemolytic anemia can result from a medication reaction, from the immune system attacking the red blood cells (autoimmune hemolytic anemia), from destruction of blood cells passing through diseased heart valves, and other causes.

Referring to hemolysis, the destruction of red blood cells which leads to the release of hemoglobin from within the red blood cells into the blood plasma. Hemolytic anemia, for example, is anemia (“low blood”) due to the destruction (rather than the underproduction) of red blood cells. Etymology: The word “hemolytic” is made up of “hemo-“, blood + “lytic”, the disintegration of cells.

The destruction of red blood cells which leads to the release of hemoglobin from within the red blood cells into the blood plasma. Etymology: The word “hemolysis” is made up of “hemo-“, blood + “lysis”, the disintegration of cells.

The presence of free hemoglobin in the urine may make the urine look dark. Normally, there is no hemoglobin in the urine. Hemoglobinuria is a sign of a number of abnormal conditions, such as bleeding and paroxysmal nocturnal hemoglobinuria.

The most common type of abnormal hemoglobin and the basis of sickle cell trait and sickle cell anemia. Hemoglobin S differs from normal adult hemoglobin (called hemoglobin A) only by a single amino acid substitution (a valine replacing a glutamine in the 6th position of the beta chain of globin). Recognition of this tiny change in the hemoglobin molecule marked the opening of molecular medicine.

Hemoglobin is the oxygen-carrying pigment in the blood, the predominant protein in the red blood cells. In the routine laboratory test for hemoglobin (Hb), it is usually measured as total hemoglobin and the result is expressed as the amount of hemoglobin in grams (gm) per deciliter (dl) of whole blood, a deciliter being 100 milliliters. The normal…

A minor component of hemoglobin to which glucose is bound. Abbreviated HbA1c. HbA1c levels depend on the blood glucose concentration: The higher the glucose concentration in blood, the higher the level of HbA1c. Levels of HbA1c are not influenced by daily fluctuations in the blood glucose concentration but reflect the average glucose levels over the prior 6 to 8…

The oxygen-carrying pigment and predominant protein in the red blood cells. Hemoglobin forms an unstable, reversible bond with oxygen. In its oxygenated state it is called oxyhemoglobin and is bright red. In the reduced state it is called deoxyhemoglobin and is purple-blue. Each hemoglobin molecule is made up of four heme groups surrounding a globin group. Heme contains iron and gives a…