Disease Glossary A–Z

Chronic inflammatory skin condition caused by blocked hair follicles, excess sebum, and Cutibacterium acnes bacteria. Affects 85% of adolescents and many adults.

Neurodevelopmental disorder characterised by persistent inattention, hyperactivity, and impulsivity that interferes with functioning. Affects 5–7% of children and 2–5% of adults.

Progressive neurodegenerative disease and the most common form of dementia. Characterised by amyloid plaques, tau tangles, and progressive loss of memory and cognitive function.

Deficiency of red blood cells or haemoglobin, reducing oxygen delivery to tissues. Iron-deficiency anaemia is the most common nutritional deficiency worldwide.

Group of conditions characterised by excessive fear, worry, and related behavioural disturbances. Includes generalised anxiety disorder, panic disorder, and social anxiety disorder.

Degenerative joint disease caused by breakdown of cartilage, leading to pain, stiffness, and reduced mobility. The most common form of arthritis, affecting 500 million people globally.

Chronic inflammatory airway disease characterised by reversible airflow obstruction, bronchospasm, and airway hyperresponsiveness. Affects 300 million people worldwide.

Neurodevelopmental condition characterised by differences in social communication, restricted interests, and repetitive behaviours. A spectrum with wide variation in presentation and support needs.

Persistently elevated arterial blood pressure (≥130/80 mmHg). The leading modifiable risk factor for stroke, heart attack, and kidney disease. Affects 1.28 billion adults worldwide.

Malignant tumour originating in breast tissue. The most common cancer in women worldwide. Risk factors include age, family history, hormonal factors, and lifestyle.

Group of diseases involving uncontrolled cell growth and potential spread to other parts of the body. Over 100 distinct types exist, with different causes, treatments, and prognoses.

Complex, debilitating condition characterised by profound fatigue not relieved by rest, post-exertional malaise, cognitive impairment, and sleep disturbance. Cause remains incompletely understood.

Autoimmune disorder triggered by gluten ingestion in genetically predisposed individuals, causing small intestinal inflammation and malabsorption. Affects approximately 1% of the population.

Acute upper respiratory tract infection caused by over 200 viruses, most commonly rhinovirus. Characterised by runny nose, sore throat, cough, and mild fever. Resolves in 7–10 days.

Cancer of the colon or rectum. The third most common cancer worldwide. Risk factors include age, family history, inflammatory bowel disease, diet, and lifestyle.

Progressive inflammatory lung disease causing obstructed airflow. Includes chronic bronchitis and emphysema. Primarily caused by smoking. Fourth leading cause of death globally.

Chronic inflammatory bowel disease that can affect any part of the gastrointestinal tract. Characterised by transmural inflammation, skip lesions, and periods of flare and remission.

Syndrome of progressive cognitive decline severe enough to interfere with daily life. Alzheimer's disease accounts for 60–70% of cases. Other types include vascular, Lewy body, and frontotemporal dementia.

Common mental health disorder characterised by persistent low mood, loss of interest, fatigue, and cognitive changes. Affects 280 million people worldwide. Leading cause of disability.

Autoimmune destruction of pancreatic beta cells resulting in absolute insulin deficiency. Requires lifelong insulin therapy. Distinct from type 2 diabetes in cause and management.

Metabolic disorder characterised by insulin resistance and progressive beta-cell dysfunction, resulting in hyperglycaemia. Strongly associated with obesity, inactivity, and diet. Affects 537 million adults globally.

Chronic inflammatory skin condition characterised by dry, itchy, inflamed skin. Often begins in childhood and may persist into adulthood. Associated with asthma and allergic rhinitis.

Condition where tissue similar to the uterine lining grows outside the uterus, causing pain, inflammation, and potential infertility. Affects approximately 10% of women of reproductive age.

Neurological disorder characterised by recurrent unprovoked seizures caused by abnormal electrical activity in the brain. Affects 50 million people worldwide.

No Coeheal coverage yet for this condition.

Regulated rise in core body temperature above 38°C (100.4°F), orchestrated by the hypothalamus in response to infection or inflammation. A feature of the immune response, not a malfunction.

Chronic condition characterised by widespread musculoskeletal pain, fatigue, sleep disturbance, and cognitive difficulties. Involves central sensitisation — amplified pain processing in the nervous system.

Chronic condition where stomach acid flows back into the oesophagus, causing heartburn, regurgitation, and potential oesophageal damage. Affects 20% of adults in Western countries.

Inflammatory arthritis caused by deposition of monosodium urate crystals in joints, typically the big toe. Caused by hyperuricaemia from excess uric acid production or reduced excretion.

Acute blockage of a coronary artery, causing ischaemic death of heart muscle. Usually caused by rupture of an atherosclerotic plaque with superimposed thrombosis. Medical emergency.

Narrowing of the coronary arteries due to atherosclerosis, reducing blood supply to the heart muscle. Leading cause of death globally. Manifests as angina, heart attack, or sudden cardiac death.

Inflammation of the liver, most commonly caused by viral infection (hepatitis A, B, C, D, E). Can also be caused by alcohol, drugs, or autoimmune conditions. Chronic hepatitis B and C are leading causes of cirrhosis and liver cancer.

HIV (Human Immunodeficiency Virus) attacks CD4+ T cells, progressively impairing immune function. AIDS (Acquired Immunodeficiency Syndrome) is the advanced stage. Antiretroviral therapy has transformed HIV into a manageable chronic condition.

No Coeheal coverage yet for this condition.

Underactive thyroid gland producing insufficient thyroid hormone, causing fatigue, weight gain, cold intolerance, and cognitive slowing. Hashimoto's thyroiditis is the most common cause in developed countries.

Umbrella term for chronic inflammatory conditions of the gastrointestinal tract, primarily Crohn's disease and ulcerative colitis. Involves dysregulated immune response to gut microbiota.

Acute respiratory illness caused by influenza A or B viruses. More severe than the common cold, with systemic symptoms including high fever, myalgia, and fatigue. Seasonal epidemics cause 290,000–650,000 deaths annually.

Persistent difficulty initiating or maintaining sleep, or non-restorative sleep, causing daytime impairment. Affects 10–30% of adults chronically. Associated with depression, anxiety, and cardiovascular disease.

Functional gastrointestinal disorder characterised by abdominal pain, bloating, and altered bowel habits without structural abnormality. Affects 10–15% of the global population.

Progressive loss of kidney function over months or years. Often caused by diabetes and hypertension. Affects 10% of the global population. Advanced CKD requires dialysis or transplantation.

Accumulation of fat in the liver not caused by alcohol. Affects 25% of the global population. Closely linked to obesity, insulin resistance, and metabolic syndrome. Can progress to cirrhosis.

Malignant tumour of the lung, the leading cause of cancer death worldwide. Strongly associated with smoking (85% of cases). Includes non-small cell (NSCLC) and small cell (SCLC) types.

Chronic autoimmune disease where the immune system attacks healthy tissue in multiple organ systems. Characterised by periods of flare and remission. Predominantly affects women of childbearing age.

Progressive deterioration of the macula (central retina), causing loss of central vision. The leading cause of blindness in adults over 50 in developed countries. Age-related macular degeneration has dry and wet forms.

Natural biological process marking the end of menstrual cycles, defined as 12 consecutive months without a period. The perimenopause transition involves hormonal fluctuations causing hot flushes, sleep disruption, and mood changes.

Cluster of conditions — central obesity, hypertension, hyperglycaemia, high triglycerides, and low HDL — that together significantly increase cardiovascular and diabetes risk. Affects 25–30% of adults in developed countries.

Recurrent neurological disorder characterised by moderate-to-severe headache, often unilateral and pulsating, with nausea, vomiting, and sensitivity to light and sound. Affects 15% of the global population.

Temporary disruption of blood flow to the brain causing stroke-like symptoms that resolve within 24 hours. A medical emergency and the most powerful warning sign of imminent stroke. 10–15% stroke risk within 90 days.

Autoimmune disease where the immune system attacks the myelin sheath of nerve fibres in the brain and spinal cord, causing demyelination and neurological dysfunction. Affects 2.8 million people worldwide.

Excess body fat accumulation (BMI ≥30) that presents a risk to health. A complex, multifactorial condition driven by genetic, environmental, and behavioural factors. Affects 650 million adults globally.

Skeletal disease characterised by reduced bone mass and microarchitectural deterioration, increasing fracture risk. Affects 200 million women worldwide. Hip fractures carry 20–30% one-year mortality in older adults.

Progressive neurodegenerative disorder caused by loss of dopaminergic neurons in the substantia nigra. Characterised by tremor, rigidity, bradykinesia, and postural instability. Second most common neurodegenerative disease.

Common endocrine disorder in women of reproductive age, characterised by hyperandrogenism, ovulatory dysfunction, and polycystic ovaries. Associated with insulin resistance and metabolic syndrome.

Infection of the lung parenchyma causing inflammation and fluid accumulation in the alveoli. Can be bacterial, viral, or fungal. Leading infectious cause of death in children under 5 worldwide.

Malignant tumour of the prostate gland. The most common cancer in men. Most cases are slow-growing; some are aggressive. PSA screening and biopsy are used for detection.

Chronic autoimmune skin condition causing rapid skin cell turnover, resulting in thick, scaly plaques. Affects 2–3% of the global population. Associated with psoriatic arthritis and cardiovascular disease.

Chronic autoimmune inflammatory arthritis primarily affecting synovial joints. Causes joint destruction, deformity, and systemic inflammation. Affects 1% of the global population, predominantly women.

Age-related progressive loss of skeletal muscle mass, strength, and function. Begins at age 30 (1–2% loss per year after 50). Major contributor to frailty, falls, and loss of independence in older adults.

Sleep disorder characterised by repeated episodes of partial or complete upper airway obstruction during sleep, causing oxygen desaturation and sleep fragmentation. Affects 10–30% of adults. Strongly associated with obesity.

Sudden interruption of blood supply to the brain causing neurological deficit. Ischaemic stroke (87%) is caused by clot; haemorrhagic stroke (13%) by vessel rupture. Second leading cause of death and leading cause of adult disability worldwide.

Malignant tumour of the thyroid gland. The most common endocrine malignancy. Most cases (papillary and follicular) have excellent prognosis with treatment. Anaplastic thyroid cancer is rare but aggressive.

See Diabetes (Type 2). Metabolic disorder characterised by insulin resistance and progressive beta-cell dysfunction. Affects 537 million adults globally and is largely preventable through lifestyle.

Chronic inflammatory bowel disease limited to the colon and rectum. Characterised by continuous mucosal inflammation, bloody diarrhoea, and abdominal pain. Periods of flare and remission.

Bacterial infection of the urinary tract, most commonly the bladder (cystitis). Predominantly affects women. E. coli accounts for 80–85% of cases. Recurrent UTIs are common.

Enlarged, twisted veins most commonly in the legs, caused by incompetent venous valves and increased venous pressure. Affects 23% of adults. Can cause pain, swelling, and skin changes.

See Obesity. Excess body fat accumulation driven by energy imbalance, genetic predisposition, hormonal factors, and environmental influences.