An increase in the proportion of cells (haematocrit) in the blood, owing to an increased volume of red blood cells or reduced volume of blood fluid (plasma).
polycythaemia
polycythaemia
One of the myeloproliferative disorders, in which too many red blood cells are produced by the bone marrow.
polydipsia
Excessive thirst leading to increased intake of water or other fluids.
polymerase chain reaction
A technique that involves the isolation and analysis of genetic material or DNA. Abbreviated to PCR.
polymyalgia rheumatica
A painful condition in which the muscles supporting the neck, shoulders, hips and thighs become inflammed.
polymyositis
A rare autoimmune disease that causes pain and weakness in muscles.
polyneuropathy
A neorological disorder that occurs when peripheral nerves throughout the body malfunction.
polyp
A growth on the surface of a mucous membrane (a surface that secretes mucus, lining any body cavity that opens to the outside of the body).
polyps
Growths on the surface of a mucous membrane (a surface that secretes mucous), lining any body cavity that opens to the outside of the body.
polyuria
Passing excessively large volumes of urine. It may be a symptom of diabetes.
pompholyx
A type of eczema where there are itchy blisters on the hands and feet, followed by inflamed, dry skin.
porphyria
The accumulation of substances called porphyrians which are caused by some enzyme deficiencies and sometimes lead to abdominal pain.
porphyrins
A group of chemicals that help to form many important substances in the body, including haemoglobin.
post-coital
Occurring after coitus (sexual intercourse).
Post-herpetic neuralgia
Pain caused by damage to nerves following an infection by the herpes virus.
post-ictal
Relating to the state of confusion and drowsiness following a seizure.
post-inflammatory hyperpigmentation
A darkening of the skin due to increased amounts of pigment. It usually occurs during the healing process following a skin disease.
post-inflammatory hypopigmentation
White patches on the skin caused by reduced amounts of pigment following inflammation.
post-menopausal
After the menopause - technically only once a woman has had no menstrual period for one year.
post-traumatic stress disorder
A set of psychological symptoms that follows a severely traumatic event.
posterior cranial fossa
part of the intracranial cavity.
posterior fossa
A small space in the skull found near the brain stem and the cerebellum.
posterior uveitis
Inflamation of the uvea, that part of the eye consisting of the iris,the ciliary body and the choroid.
postural hypotension
A fall in blood pressure on standing up, or sitting up from a lying position.