low blood pressure
Q blood group system
| blood sugar, high | Elevated levels of blood glucose (hyperglycaemia) can be found in a number of conditions. The hyperglycaemia leads to spillage of glucose into the urine, hence the term sweet urine. (Diabetes mellitus means sweet urine. ) (12 Dec 1998) |
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| blood sugar, low | The sugar here is glucose. Low blood glucose constitutes hypoglycaemia. Hypoglycaemia is only significant when it is associated with symptoms. It has many causes including drugs, liver disease, surgical absence of the stomach, pre-diabetes, and rare tumours that release excess insulin. (12 Dec 1998) |
| blood-testis barrier | The membrane in the testis that separates sperm from the bloodstream. (09 Oct 1997) |
| blood-thinner | <haematology, pharmacology> Any substance that prevents blood clotting. Those drugs administered for prophylaxis or treatment of thromboembolic disorders are heparin, which inactivates thrombin and several other clotting factors and which must be administered parenterally and the oral anticoagulants (warfarin, dicumarol and congeners) which inhibit the hepatic synthesis of vitamin K dependent clotting factors. Anticoagulant solutions used for the preservation of stored whole blood and blood fractions are acid citrate dextrose (ACD), citrate phosphate dextrose (CPD), citrate phosphate dextrose adenine (cPDA 1) and heparin. Anticoagulants used to prevent clotting of blood specimens for laboratory analysis are heparin and several substances that make calcium ions unavailable to the clotting process, including EDTA (ethylenediaminetetraacetic acid), citrate, oxalate and fluoride. (18 Nov 1997) |
| blood transfusion | The process of infusing blood products into a patient to raise the individuals concentration of red blood cells. Blood is typed (A, B, O or AB) and crossmatched (mixed together to see if its compatible) prior to transfusion. (27 Sep 1997) |
| blood transfusion, autologous | Reinfusion of blood or blood products derived from the patient's own circulation. (12 Dec 1998) |
| blood transfusion, intrauterine | Transfusion of rh-negative blood into the peritoneal cavity of an unborn infant in the treatment of foetal erythroblastosis (erythroblastosis, foetal) in utero. (12 Dec 1998) |
| blood transfusion reaction | This refers to an immune response against transfused blood cells. Antigens, on the surface of red blood cells, are recognised as foreign proteins and can stimulate sensitised lymphocytes to produce antibodies to the red blood cell antigens. This triggers a complex immunological reaction that results in the destruction of the transfused red blood cell. The blood groups (A, B, AB, O) are classified on the basis of the presence of surface antigens on the red blood cell. Type A blood has A antigens. The plasma component of the blood contains the antibodies against all other blood group antigens other that its own. Another type of surface antigen is known as Rh factor. Rh factor is either present (Rh positive) or absent (Rh negative). Rh compatibility is another requirement for blood transfusion. Symptoms and findings of a transfusion reaction include flank pain, fever, chills, bloody urine, rash, low blood pressure, dizziness and fainting. (27 Sep 1997) |
| blood tumour | Term sometimes used to denote an aneurysm, haemorrhagic cyst, or haematoma. (05 Mar 2000) |
| blood type | The specific reaction pattern of erythrocytes of an individual to the antisera of one blood group; e.g., the ABO blood group consists of four major blood types: O, A, B, and AB. This classification depends on the presence or absence of two major antigens: A or B. Type O occurs when neither is present and type AB when both are present. The blood type is the genetic phenotype of the individual for one blood group system and may be determined using different antisera available for testing. See Blood Groups appendix. (05 Mar 2000) |
| blood urea nitrogen | Blood urea nitrogen (BUN) is a metabolic by product (in the liver) from the breakdown of blood, muscle and protein. Blood urea nitrogen can be measured from a simple venipuncture specimen. Abnormal elevation in the blood urea nitrogen can indicate renal disease, dehydration, congestive heart failure, gastrointestinal bleeding, starvation, shock or urinary tract obstruction (by tumour or prostate gland). Low BUN level can indicate liver disease, malnutrition or a low protein diet. Normal BUN levels should be between 7 and 20 mg/dl (milligrams per decilitre). (27 Sep 1997) |
| blood, urinary | Medically called haematuria, blood in the urine can be microscopic or gross. Evaluating haematuria requires consideration of the entire urinary tract. Tests used for the diagnosis of haematuria include the intravenous pyelogram (IVP), cystoscopy, and urine cytology. Management of haematuria depends upon the underlying cause. (12 Dec 1998) |
| blood-vascular system | The heart and the blood vessels by which blood is pumped and circulated through the body. (12 Dec 1998) |
| blood vessel | <anatomy> All the vessels lined with endothelium through which blood circulates. (18 Nov 1997) |
| blood vessel prosthesis | Prosthesis, constructed of either synthetic or biological material, which is used for the repair of injured or diseased blood vessels. (12 Dec 1998) |