Glossary

113 health terms in plain English. Use the letters to jump, or filter by a word.

Absolute risk: Your actual chance of something happening over a period of time, such as 2 in 100 over 10 years. It is more useful than relative risk for personal decisions.
Acute: Starting suddenly and usually lasting a short time. The opposite of chronic.
Adequate intake: An estimate of the amount of a nutrient that seems enough for most people, used when there is not enough evidence to set an exact requirement.
Allergy: When the immune system reacts to a harmless substance, such as a food protein or pollen, as if it were a threat.
Allostatic load: The cumulative wear on the body from repeated or long-lasting stress responses.
Amino acid: A building block of protein. Nine amino acids are essential, meaning they must come from food.
Anaemia: Having too few red blood cells or too little haemoglobin to carry enough oxygen.
Anaphylaxis: A severe, life-threatening allergic reaction that needs adrenaline and an ambulance.
Antibody: A protein made by the immune system that recognises and helps neutralise a specific target, such as a virus.
Antigen: Anything the immune system can recognise and respond to, such as part of a germ.
Antioxidant: A substance that neutralises reactive oxygen molecules, protecting cells from oxidative damage.
Apoptosis: Programmed cell death: a tidy, controlled way for the body to remove old or damaged cells.
Association: A link between two things seen in research. An association does not prove that one causes the other.
ATP: Adenosine triphosphate, the molecule cells use as their main energy currency.
Atrophy: Wasting away or shrinking of a tissue or organ, such as muscle that is not used.
Autoimmune: When the immune system attacks the body's own tissues.
Autonomic nervous system: The part of the nervous system that runs automatic functions such as heart rate, digestion and breathing.
Baseline: A starting measurement used for comparison with later results.
Benign: Not cancerous and not spreading to other parts of the body.
Bilateral: Affecting both sides of the body.
Bilirubin: A yellow substance made when old red blood cells are broken down. High levels cause jaundice.
Bioavailability: How much of a substance you swallow actually reaches the bloodstream in a usable form.
Biomarker: A measurable sign in the body, such as a blood test result, that reflects a process or condition.
Blinding: Keeping study participants, and often researchers, unaware of who receives the real treatment, to reduce bias.
Body mass index (BMI): Weight in kilograms divided by height in metres squared. A screening measure that cannot tell muscle from fat.
C-reactive protein (CRP): A protein the liver makes during inflammation, measured in a blood test.
Chronic: Long-lasting or recurring, often for three months or more. The opposite of acute.
Circadian rhythm: The body's roughly 24-hour internal clock.
Cofactor: A vitamin, mineral or other helper molecule an enzyme needs to work.
Cohort study: A study that follows a group of people over time to see who develops certain outcomes. It shows associations, not proof of cause.
Comorbidity: Having two or more health conditions at the same time.
Contraindication: A reason not to use a particular medicine or treatment for a particular person.
Cortisol: A hormone from the adrenal glands that helps control blood sugar, inflammation and the daily rhythm of alertness.
Cytokine: A small protein messenger that immune cells use to coordinate responses, including inflammation.
Deficiency: Not having enough of a nutrient for normal body function.
Differential diagnosis: The list of possible conditions a doctor considers when working out what is causing symptoms.
Distal: Further from the centre of the body. The hand is distal to the elbow.
DMARD: Disease-modifying anti-rheumatic drug: a type of medicine used to treat rheumatoid arthritis.
Effectiveness: How well a treatment works in everyday real-world use.
Efficacy: How well a treatment works under ideal conditions, such as in a clinical trial.
eGFR: Estimated glomerular filtration rate: an estimate of how well the kidneys filter blood, calculated from a creatinine test.
Electrolyte: A mineral salt in body fluids, such as sodium or potassium, that carries an electrical charge.
Endocrine: Relating to glands that release hormones into the blood.
Endogenous: Made inside the body.
Endothelium: The thin inner lining of blood vessels.
Enzyme: A protein that speeds up a chemical reaction in the body.
Epidemiology: The study of how often diseases occur in populations and what influences them.
Evidence grade: AskBioMap's label for how strong the evidence is: established, supported, emerging or contested.
Exogenous: Coming from outside the body, such as a medicine or food.
False negative: A test result that says a condition is absent when it is actually present.
False positive: A test result that says a condition is present when it is actually absent.
Fasting: Not eating for a period of time, such as before some blood tests.
Ferritin: A protein that stores iron. Blood ferritin reflects the body's iron stores.
Fibrosis: Scarring of tissue, which can stiffen organs such as the liver or lungs.
Free radical: An unstable molecule that can damage cells. Reactive oxygen species are one type.
Glycogen: The stored form of glucose in the liver and muscles.
Gut microbiome: The community of microbes living in the digestive tract, mostly in the large intestine.
Haemoglobin: The iron-containing protein in red blood cells that carries oxygen.
Half-life: The time it takes for the amount of a substance in the body to fall by half.
HbA1c: A blood test showing average blood glucose over the past two to three months.
Homeostasis: The body's way of keeping internal conditions, such as temperature and blood sugar, stable.
Hormone: A chemical messenger released into the blood that affects distant organs.
Hypertrophy: An increase in the size of cells, such as muscle growth after strength training.
Idiopathic: Of unknown cause.
Incidence: The number of new cases of a condition in a population over a period of time.
Inflammation: The body's protective response to injury or infection, with redness, warmth, swelling and pain.
Insulin resistance: When cells respond less to insulin, so the pancreas must make more to keep blood sugar normal.
Intolerance: A reaction to a food or substance that does not involve the immune system, such as lactose intolerance.
Ischaemia: Not enough blood flow to a tissue, so it is short of oxygen.
Jaundice: Yellowing of the skin and eyes caused by high bilirubin.
Localised: Limited to one area of the body.
Malabsorption: Poor absorption of nutrients from the gut, as in untreated coeliac disease.
Malignant: Cancerous, with the ability to invade nearby tissue and spread.
Meta-analysis: A study that combines the results of several similar studies to get a more reliable overall answer.
Metabolism: All the chemical reactions in the body that build up and break down molecules and release energy.
Microbiome: A community of microorganisms living in a particular place, such as the gut or skin.
Mitochondria: Structures inside cells that turn food and oxygen into ATP.
mmol/L: Millimoles per litre: the unit Australia uses for many blood tests, such as glucose and cholesterol.
Neurotransmitter: A chemical messenger that carries signals between nerve cells.
Number needed to treat (NNT): How many people need a treatment for one person to benefit. Lower numbers mean a more effective treatment.
Observational study: A study that watches what happens without assigning treatments. It can find links but not prove cause.
Oedema: Swelling caused by fluid building up in body tissues.
Off-label: Using a medicine for a purpose, dose or group that is not on its approved product information.
Oxidative stress: An imbalance where reactive oxygen molecules outpace the body's antioxidant defences.
Palliative: Care focused on comfort and quality of life rather than cure.
Pathogen: A germ that can cause disease, such as a virus, bacterium, fungus or parasite.
Pathophysiology: How a disease changes normal body function.
Peripheral neuropathy: Damage to nerves outside the brain and spinal cord, often felt as tingling, burning or numbness in the hands or feet.
Placebo: A dummy treatment with no active ingredient, used to compare against a real treatment in trials.
Prebiotic: A type of fibre that gut microbes can feed on.
Prevalence: The proportion of a population that has a condition at a given time.
Probiotic: Live microorganisms that may provide a health benefit when taken in sufficient amounts.
Prognosis: The likely course and outcome of a condition.
Prophylaxis: Treatment given to prevent a condition rather than treat it.
Proximal: Closer to the centre of the body. The elbow is proximal to the wrist.
Randomised controlled trial: A study that randomly assigns people to a treatment or a comparison, the strongest single design for testing cause and effect.
Receptor: A protein on or in a cell that a specific hormone, messenger or medicine binds to, triggering a response.
Reference interval: The range of test results found in most healthy people, printed on your lab report. Being outside it does not always mean something is wrong.
Refractory: Not responding to treatment.
Relapse: The return of a condition after a period of improvement.
Relative risk: How much more or less likely something is in one group compared with another. It can make small risks sound large.
Remission: A period when a condition's signs and symptoms are reduced or gone.
Sensitivity (of a test): How well a test correctly identifies people who have a condition.
Sign: Something a doctor can observe or measure, such as a rash or high blood pressure.
Specificity (of a test): How well a test correctly identifies people who do not have a condition.
Standard drink: A drink containing about 10 grams of alcohol.
Statistically significant: A result unlikely to be due to chance alone. It does not necessarily mean the effect is large or important.
Symptom: Something a person feels and reports, such as pain or tiredness.
Syndrome: A group of signs and symptoms that tend to occur together.
Systemic: Affecting the whole body rather than one part.
Titration: Gradually adjusting a medicine dose to find the right amount.
Unilateral: Affecting one side of the body.
UV index: A scale of the strength of the sun's ultraviolet radiation. In Australia, sun protection is recommended at 3 or above.