- HAART
Highly
Active Antiretroviral Therapy, a term used to describe HIV combination therapy
with three or more drugs.
- haematocrit
Measurement
of the proportion of red cells in the blood.
- haematology
Study
of blood conditions. Also used to describe a range of biochemical tests carried
out on the blood.
- haemoglobin
Red-coloured,
oxygen-carrying chemical in red blood cells.
- haemophilia
Inherited
illness in which the blood does not always clot, often requiring injections of
blood clotting agents.
- half-life
The
amount of time it takes for half a dose of any drug to be eliminated from the
body.
- HAV
Abbreviation of
hepatitis A virus.
- hazard
Expresses the risk that, during one very short moment in time, a person will experience an event, given that they have not already done so.
- hazard ratio
Comparing one group with another, expresses differences in the risk of something happening. A hazard ratio above 1 means the risk is higher in the group of interest; a hazard ratio below 1 means the risk is lower. Similar to ‘relative risk’.
- HBc Ag (hepatitis B core antigen)
An element of the viral capsule, produced by hepatitis B. May be detected in the liver, but not in blood.
- HBe Ag (hepatitis B “e” antigen)
A protein of the viral envelope, produced by hepatitis B. It suggests that the virus is replicating.
- HBs Ag (hepatitis B surface antigen)
A protein on the surface of hepatitis B; in a blood test, positive HBsAg
usually means someone has acute or chronic hepatitis B infection. They have
some ongoing viral replication, even when their disease is inactive, and can transmit the virus
to others.
- HBV
Abbreviation of
hepatitis B virus.
- HCV
Abbreviation of
hepatitis C virus.
- heartburn
A burning chest pain or discomfort that occurs after eating.
- helper cell
An
alternative name for CD4 T cells.
- hepatic
To
do with the liver.
- hepatitis
Injury to the liver with inflammation of the liver cells. May be caused by an
infection with a virus (hepatitis A, hepatitis B, etc.), or by alcohol abuse,
other toxins, other infections, too much fat in liver cells, or an autoimmune
process (the body attacks itself).
- hepatocellular carcinoma (HCC)
Liver cancer. A long-term complication of chronic inflammation of the liver or cirrhosis.
- hepatocyte
Cell of the liver.
- hepatotoxicity
Side-effects
affecting the liver.
- herpes simplex
A
viral infection which may cause sores around the mouth or genitals.
- hickman catheter
A
type of catheter that is surgically implanted, with one end leading into a
large vein in the chest, and the other end remaining outside the chest. HICKMAN
is a registered trade mark of C R Bard Inc.
- histology
Examining
a sample of cells under a microscope to determine if they are normal or if
there is evidence of infections or tumours.
- historical control
A
comparison group of people not taking an experimental drug, taken from previous
clinical trials.
- homeopathy
A
therapy which aims to treat illness using tiny quantities of the substance that
caused the illness, or of a substance that causes similar symptoms.
- hormone
A
chemical which stimulates or suppresses cell and tissue activity.
- human papilloma virus (HPV)
A
group of wart-causing viruses which are also responsible for cancer of the
cervix and some anal cancers.
- hyper
Prefix
meaning higher than usual.
- hyperglycaemia
Raised
concentration of sugar in the blood.
- hyperlipidaemia
High
levels of fat in the blood.
- hypersensitivity
An
allergic reaction.
- hypertension
Raised
blood pressure.
- hypertriglyceridaemia
High
levels of triglycerides in the blood.
- hypo
Prefix
meaning lower than usual.
- hypothesis
A tentative explanation for an observation, phenomenon, or scientific problem. The purpose of a research study is to test whether the hypothesis is true or not.
- hypothesis test
Any
statistical test that aims to assess whether the differences observed are
likely to have occurred by chance.
- hypoxaemia
Reduced
amounts of oxygen in the blood, usually caused by pneumonia.