Absolute Neutrophil Count (ANC) – this refers to the number of a particular type of white blood cell (neutrophil) per volume of blood. Neutrophils are important for fighting infections Acute – disease or symptoms of rapid onset or short duration.

Acute – disease or symptoms of rapid onset or short duration

Alanine transaminase (ALT) – this is a blood test used in the diagnosis and study of acute liver disease.

Alkaline phosphatase (ALP) – this is an enzyme found throughout the body. High blood levels can indicate liver disease or bone problems.

Allergy – an extreme sensitivity to a substance, which may need to be avoided.

Alopecia – hair loss.

Anaemia – occurs when the number of red blood cells per volume of blood is reduced.

Anaesthetic – this is used to sedate or temporarily cause sleep so that surgery can be carried out painlessly.

Analgesic – medication used to reduce pain.

Antibiotic – medications that destroy or stop the growth of bacteria and so helps treat bacterial infection.

Anti-emetic – medicines that controls nausea and vomiting.

Anti-fungal – medications that destroy or stop the growth of fungi and so helps to treat fungal infection.

Anti-pyretic – medications that reduce fever (pyrexia) by lowering the body temperature, for example, paracetamol.

Aspartate transaminase (AST) – this is a blood test used in the diagnosis and study of acute liver disease.

Ataxia – a type of poor coordination and unsteadiness.

Autosomal recessive a type of inheritance where the presence of one copy of a faulty gene does not affect the individual him or herself. However, when two carriers of the same faulty gene have children there is a 25 per cent (or 1 in 4) chance of a child inheriting two copies of the faulty gene (one from each parent) for each pregnancy. If this happens, the child is affected by the disorder.

Biopsy – the removal of a small piece of tissue from an organ or part of the body for microscopic examination.

Blood Count (BC) – the numbers of different blood cells in a volume of blood. A full blood count (FBC) measures the amount of haemoglobin, red cells and white cells as well as platelets per volume of blood.

Blood group – this is how a person’s blood may be classified and the most common types are A,B, AB and O.

Blood transfusion – this involves giving blood previously donated by one person to another person.

Bone marrow – this spongy material in the centre of the large bones produces all the different blood cells.

Bone Marrow Transplantation – bone marrow transplantation (BMT) transfer of bone marrow, obtained by aspiration usually from the hip bones, from a donor – either related or unrelated
– to a recipient. The donor bone marrow replaces the recipient bone marrow, giving the recipient a new immune system and curing the immunodeficiency (see also Haematopoietic stem cell transplantation).

Catheter – a thin flexible tube used to pass fluid into the body or to drain fluid out.

Cell – the living units from which animals and plants are built (for example, blood cells, brain cells). They are so tiny that thousands of cells could sit on a pin head.

Central line – a tube inserted under the skin into a large vein to make the giving of medication and the taking of blood samples easier.

Central Nervous System (CNS) – the brain and the spinal cord.

Cerebrospinal fluid– a watery liquid that surrounds the brain and spinal cord

Chemotherapy (Chemo) – chemical substances (medication) used to treat cancer as well as LCH & HLH.

Chromosomes – thread-like structures located inside the nucleus of cells. Each chromosome is made of protein and DNA.

Chronic – describing a disease of long duration, often of gradual onset. The term does not imply anything about the severity of a disease.

Computerised Tomography (CT) scan – takes a number of x-ray pictures of the body from different angles and uses a computer to convert them into cross sectional x-ray pictures or slices’ of the body. A higher radiation dose is received by the patient than with some conventional X-ray techniques, but the diagnostic information obtained is far greater.

Culture – when infection is suspected, samples of blood, urine, throat secretions etc. are taken and tested to try to identify the type of infection and the most appropriate treatment required.

Cytotoxic – a drug that damages or destroys cells.

Diagnosis – the exact name and type of the illness.

Electrolytes – a general term for the many minerals necessary to provide the proper environment for the cells of the body. These minerals include calcium, potassium, sodium, and chloride.

Emesis – vomiting.

Enteral feeding – feeding through a tube passed directly into the stomach.
There are two methods:
1) a tube is passed down through the nose (NG, nasogastric tube) or
2) a connection is made between the stomach and the skin of the abdomen via a short operation (PEG tube).
Both kinds of tube can safely stay in place for months

Erythrocyte sedimentation rate (ESR) – the distance red blood cells travel in one hour in a sample of blood as they settle to the bottom of a test tube. The sedimentation rate is increased in inflammation, infection, cancer, rheumatic diseases, and diseases of the blood and bone marrow.

Febrile neutropenia – having a raised body temperature/fever while having low levels of white blood cells which fight infection (neutrophils) in the circulating blood.

Gastro intestinal – relating to the stomach and the intestines.

Gastrostomy tube – a tube inserted through the wall of the abdomen directly into the stomach. This is a surgical procedure and is done under general anaesthesia. It can be used to give drugs, liquids and liquid food. This is also called a PEG tube.

Gene – section of DNA on a chromosome that codes for a functional RNA molecule and thus a protein. Put another way, a word, rather than a letter, in the genetic code. Genes are the fundamental units of inheritance that carry the instructions for how the body grows and develops

Glomerular Filtration Rate (GFR) – a test to see how well the kidneys are working.

Haematology – the study of blood and blood diseases.

Haematuria – blood in the urine.

Haemoglobin – the substance within red blood cells that carries oxygen to the tissues of the body. The concentration of haemoglobin in blood is used as a measure of how many red cells there are per volume of blood.

Haemorrhage – bleeding.

Histopathology – the microscopic study of cells in disease.

Hydration – this reflects how much body water a person has. Dehydration means too little, ell-hydrated means normal and over hydrated means too much.

Hypotension – low blood pressure.

Immune system – the body’s defence against infection, disease and foreign substances.

Immunoglobulin – antibodies (type of protein) that are produced by certain white blood cells and play an essential role in the body’s immune system. It is sometimes necessary to give immunoglobulin (antibodies) collected from donors to patients to support their immune system (e.g. IVIG, ZIG).

Immuno-suppression – reduced function of the immune system leading to an increased risk of infection.

Infusion – the introduction of a fluid into a vein (into the blood stream).

Intravenous (I.V.) – the administration of a drug or fluid directly into a vein (into the blood stream).

Kidney – organ that removes waste substances from the body and also maintains the body’s mineral and water balance.

Lesion – a change in tissue structure due to injury or disease. Ulcers, tumours, abscesses etc. may all be referred to as lesions.

Leucocytes – white blood cells.

Leucocytosis – a higher than normal concentration of white blood cells in the circulating blood.

Leucopenia – a lower than normal concentration of white blood cells in the circulating blood.

Liver – this part of the body takes part in many complex functions necessary for life, including digestion, production of certain blood proteins and elimination of many of the body’s waste products.

Lymph nodes – these are more commonly known as ‘glands’ and are located in many places throughout the body. Lymph nodes filter the lymphatic fluid and store special cells that play an important role in defending the body against infections.

Lymphocytes – white blood cells responsible for the production of antibodies and for the direct destruction of invading organisms.

Macrophage – occur in the walls of blood vessels (adventitial cells) and in loose connective tissue (histiocytes, phagocytic reticular cells). Macrophages are usually immobile but become actively mobile when stimulated by inflammation; they also interact with lymphocytes to facilitate antibody production.

Macrophage activating syndrome – is a severe, life-threatening illness caused by the excessive production of types of white blood cells called T cells and macrophages. The term is typically used for the HLH-like syndrome that can occur in patients with systemic onset juvenile arthritis.

Nasogastric tube (NG tube) – a thin tube that is inserted through the nose, down the throat and into the stomach. It can be used to give drugs, liquids and liquid food.

Nasojejenal tube (NJ tube) – a thin tube that is inserted through the nose, down the throat, through the stomach and into the small bowel. It can be used to give drugs, liquids and liquid food.

Nausea – feeling sick.

Neurology – branch of medical science dealing with the nervous system.

Neutrophils – white blood cells that fight acute infection.

Oncology – the study, diagnosis and treatment of tumours, especially cancers.

Paediatric – the branch of medicine that specialises in the study and treatment of children.

Palliation – to relieve a symptom (like pain) but not necessarily a cure.

Pancytopenia – decrease of red cells, white cells and platelets in the blood.

PET scan – Positron Emission Tomography.

Scan – uses short-lived radioactive substances linked to a substance commonly used by the body (e.g. sugar) to produce three-dimensional colour pictures of where in the body this substance is being used.

Plasma – the liquid portion of blood. It is a fluid which contains water and other components in which red cells, white cells and platelets are suspended.

Platelets – the tiny cells in circulating blood which aid blood clotting.

Prognosis – an estimate of the outcome of a disease based on the patient’s current condition and accumulated medical knowledge about that disease and its best treatment.

Pyrexia – fever or abnormally high body temperature.

Reactivation – return of symptoms and signs of disease after a period of improvement (often used in the context of LCH & HLH).

Radiotherapy – the use of high-energy radiation to kill cells and shrink lesions.

Red blood cell – this is the cell in the blood that carries oxygen and contains the pigment haemoglobin. It is produced in the bone marrow.

Reduced-intensity conditioning – is a less toxic pre-transplant therapy with the goal of suppressing the patient’s immune system enough so that it will accept donor stem cells while reducing the side effects of high dose chemotherapy The RIC may be used in some HLH patients, as well as some LCH patients with severe, resistant disease.

Regression – a decrease in the size of a lesion or in the extent of disease in the body.

Relapse – the return of signs and symptoms of disease after a period of improvement (often used in the context of cancer).

Remission – a period of well-being with no signs of disease. There is no longer any evidence of the disease using the available investigations.

Renal – relating to kidneys.

Respiratory – related to the process of breathing.

Sepsis – infection.

Septicaemia – bacteria within the bloodstream causing someone to be very unwell.

Shingles – a painful or itchy rash in a particular area of the body caused by the same virus that causes chickenpox. People can only get shingles if they previously had chickenpox. Someone who has not had chickenpox can catch chickenpox from a person with shingles if they were in direct touching contact with the rash.

Sinuses – hollow spaces within the bones of the face.

Spleen – an organ near the stomach that forms part of the immune system. It is made up mainly of white blood cells.

Stomatitis – sore mouth.

Temperature spike – when body temperature suddenly rises.

Thrombocytopenia – less than the normal number of platelets in the blood.

Total Parenteral Nutrition (TPN) – a method of delivering nutrition or other substances directly into a vein (IV), bypassing the digestive system.

Toxicity – unpleasant or dangerous side-effects of treatment.

Urinary tract – the organs and structures involved with the production and removal of urine (i.e. kidneys, ureters, bladder and urethra).

Varicella – Chickenpox – an infection caused by the Varicella Zoster virus (VZV). The same virus causes shingles.

Viruses – a group of very small organisms that can produce disease. Viral infections include the common cold, chickenpox, measles, mumps and cold sores.

White blood cells – cells in the blood that are important in fighting infection (neutrophils, lymphocytes, etc.).

Zoster ImmunoGlobulin (ZIG) – antibodies against Chickenpox (obtained from donors who previously had chickenpox). This can be given to individuals with lowered immunity who have not had chickenpox before to protect them if they came into contact with someone who has chickenpox.

Please be advised that all the information you read here is not a replacement for the advice you will get from your consultant and their team.

Help ensure that we can continue to bring you this vital informational material, make a donation today


Your support is vital to ensure that we can continue to deliver our Research and Information Programmes. Thank you.

Make a donation