Medical Definitions - T
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Tachycardia - abnormally rapid beating of the heart.
Tachypnea - very rapid respiration.
Tetrasomy - the presence of two extra chromosomes of one type in an otherwise diploid cell.
Thrombocyte - see platelet.
Thrombocytopenia - an abnormal drop in the number of blood cells involved in forming blood clots. These cells are called platelets.
Tolazoline - a smooth muscle relaxant and peripheral vasodilator; used as the hydrochloride salt.
TPN - see also lipids; total parenteral nutrition; fluid high in calories administered via IV for nutrition/nourishment.
TR - a measure of pulmonary hypertension.
Trabecula(e) - a small mineralized spicule that forms a network in spongy bone. A fibrous strand of connective tissue that supports it in place.
Trabeculation - the formation or the occurrence of trabecula(e).
Tracheal occlusion - a procedure that, like in-utero repair, involves an operation on the mother during pregnancy. Rather than correcting the diaphragm, this procedure clamps off the baby's trachea, in the hopes of causing the lungs to grow and push the organs back into the abdominal cavity.
Tracheostomy - also called a trach; a 2- to 3-inch metal or plastic tube that keeps the stoma and trachea open.
Traumatic diaphragmatic hernia - a type of diaphragmatic hernia which is acquired through an abdominal injury. This is in contrast to a congenital diaphragmatic hernia, which is present from birth.
Tricuspid valve regurgitation - also known as tricuspid insufficiency; a disorder in which the heart's tricuspid valve does not close properly, causing blood to flow backward (leak) into the right upper heart chamber (atrium) when the right lower heart chamber (ventricle) contracts.
Trisomy 5 Mosaicism - a very rare chromosomal disorder where there is an extra copy of chromosome 5 in some of the body's cells. Some cases with this chromosomal abnormality have no clinical symptoms. The presence of abnormalities in some cases is dependent on which body cells contain the chromosomal defect.
Trisomy 13 - also known as Patau syndrome; the condition of having three copies of chromosome 13 that results in a syndrome characterized by mental retardation and defects to the central nervous system and heart.
Trisomy 18 - also known as Edwards syndrome; there are three instead of the normal two chromosomes #18. Children with this condition have multiple malformations and mental retardation due to the extra chromosome #18. The children characteristically have low birth weight, small head (microcephaly), small jaw (micrognathia), malformations of the heart and kidneys, clenched fists with abnormal finger positioning, and malformed feet.
Trisomy 20 - a rare chromosomal disorder where there are three copies of chromosome 20 rather than the normal two which results in severe abnormalities and death.
Trisomy 21 - also known as Down syndrome or mongolism; the most common cause of mental retardation and malformation in a newborn. It occurs because of the presence of an extra chromosome.
Tumor necrosis factor (TNF) - a member of a superfamily of proteins, each with 157 amino acids, which induce necrosis (death) of tumor cells and possess a wide range of proinflammatory actions. Tumor necrosis factor is a multifunctional cytokine with effects on lipid metabolism, coagulation, insulin resistance, and the function of endothelial cells lining blood vessels. A protein made by white blood cells in response to an antigen (substance that causes the immune system to make a specific immune response) or infection. It may boost a person's immune response, and also may cause necrosis (cell death) of some types of tumor cells. Tumor necrosis factor is being studied in the treatment of some types of cancer. It is a type of cytokine.
Turner syndrome - also known as monosomy x; a chromosomal disorder affecting females wherein one of the two X-chromosomes is defective or completely absent.