John Harvey Kellogg: physician, health reformer, and sanitarium director John Harvey Kellogg American physician (1852–1943) who directed the Battle Creek Sanitarium, promoted dietary and hygiene reforms, contributed to early breakfast cereal production, and remained a cont…
Joseph Lister: pioneer of antiseptic surgery Joseph Lister British surgeon Joseph Lister (1827–1912) introduced antiseptic methods using carbolic acid, applied germ theory to surgery, and helped transform surgical safety and practice.
Juvenile idiopathic arthritis: overview, types, symptoms, diagnosis and care Juvenile idiopathic arthritis Juvenile idiopathic arthritis (JIA) is a group of chronic inflammatory joint disorders beginning before age 16. This entry explains subtypes, symptoms, causes, diagnosis, treatment…
Kaposi's sarcoma: causes, forms, signs, diagnosis and treatment Kaposi's sarcoma Kaposi's sarcoma is a tumor linked to human herpesvirus 8 (HHV‑8) that produces purple skin and internal lesions. Overview of types, clinical features, diagnosis, therapy, and hist…
Keloid: benign overgrowths of scar tissue Keloid Keloids are raised, benign scars that extend beyond the original wound. This article explains appearance, causes, risk factors, differences from hypertrophic scarring, and typical…
Ketamine: medical uses, effects, history, and risks Ketamine Overview of ketamine, a dissociative anesthetic used in medicine and psychiatry, covering pharmacology, clinical uses, routes of administration, adverse effects, dependence risk, h…
Ketosis (metabolic state of elevated ketone bodies) Ketosis Ketosis is a metabolic state in which the liver produces ketone bodies from fat when carbohydrate supply is low; it occurs in fasting, low‑carbohydrate diets and certain medical co…
Kidney cancer (renal cell carcinoma, Wilms tumor and other types) Kidney cancer Malignant tumors that begin in kidney tissue. Covers main types, symptoms, risk factors, diagnosis, treatment options, and important distinctions between adult and pediatric forms.
Kidney failure (renal failure): overview, causes, diagnosis and treatment Kidney failure Kidney failure is the loss of normal kidney function. This article explains types (acute and chronic), symptoms, causes, diagnosis, treatments such as dialysis and transplant, prev…
Kidney stone disease (urolithiasis): causes, symptoms, diagnosis and treatment Kidney stone disease Kidney stone disease (urolithiasis) is formation of solid mineral deposits in the urinary tract. This article explains types, symptoms, diagnosis, treatments, prevention and notabl…
Klinefelter syndrome (47,XXY) Klinefelter syndrome A chromosomal condition in people with an extra X chromosome. It commonly affects physical development, fertility, learning and health; diagnosis by karyotype and managed with horm…
Koch's postulates: principles for linking microbes to disease Koch's postulates A clear overview of Koch's postulates: their statements, historical origins, applications to diseases like cholera and tuberculosis, limitations, and modern molecular adaptations.
Kuru: human prion disease linked to ritual cannibalism Kuru (disease) Kuru is a rare, fatal human prion disease first identified among the Fore people of Papua New Guinea. Historically transmitted by ritual cannibalism, it produces progressive ataxia…
Laminitis: disease of the hoof in horses, cattle and other ungulates Laminitis Laminitis is inflammation of the laminae that bond the hoof wall to the coffin bone. It causes pain, lameness and structural failure of the hoof; early detection, supportive care a…
Laryngeal cancer: overview, causes, diagnosis and treatment Laryngeal cancer A concise, neutral summary of laryngeal cancer covering types, anatomical sites, risk factors, signs, diagnostic methods, treatment options and rehabilitation considerations.
Lassa fever (Lassa haemorrhagic fever) Lassa fever Acute viral disease endemic in parts of West Africa caused by Lassa virus. Rodent‑borne; most infections are mild but some progress to severe hemorrhagic illness with higher fatali…
Latent autoimmune diabetes in adults (LADA) Latent autoimmune diabetes LADA is a slowly progressive, autoimmune form of diabetes with adult onset that shares features of type 1 and type 2 diabetes and often leads to insulin dependence.
Laxative: uses, types, effects, and safety Laxative Overview of laxatives: how they work, common types, uses, side effects, misuse risks, and guidance for safe use.
LD50 (Median Lethal Dose) LD50 LD50, or median lethal dose, is the amount of a substance expected to kill 50% of a tested population. It is a measure of acute toxicity with important uses, limitations, and ethic…
Lead poisoning: causes, effects, diagnosis and prevention Lead poisoning Lead poisoning is toxicity from accumulation of lead that damages multiple body systems. This article explains causes, symptoms, diagnosis, treatment, prevention and public-health…
Left-handedness: causes, characteristics, history, and everyday effects Left-handedness Left-handedness is a common variation in human motor preference. This article explains what it is, how it is measured, its possible causes, cultural history, practical effects and…
Legionnaires' disease: causes, symptoms, diagnosis, treatment, and prevention Legionnaires' disease A severe form of pneumonia caused by Legionella bacteria. Explains signs, incubation, sources of infection, diagnosis, treatment options, at‑risk groups, prevention and historical…
Leiomyosarcoma (LMS): malignant tumor of smooth muscle Leiomyosarcoma Leiomyosarcoma (LMS) is a rare, aggressive cancer of smooth muscle cells that most often affects the uterus, limbs, and trunk. Diagnosis relies on imaging and biopsy; surgery is pr…
Leishmaniasis: causes, clinical forms, diagnosis, treatment and prevention Leishmaniasis Leishmaniasis is a group of parasitic diseases transmitted by sandflies. This article summarizes causes, clinical forms, diagnosis, treatment, prevention, animal reservoirs and pub…
Leprosy (Hansen's disease) Leprosy Chronic infectious disease caused primarily by Mycobacterium leprae. Affects skin and peripheral nerves; treatable with multi‑drug therapy. Historically stigmatized, now controlled…
Leptospirosis (Weil's disease): causes, symptoms, transmission, and prevention Leptospirosis Leptospirosis is a zoonotic bacterial infection caused by Leptospira spp., transmitted from animals to humans via contaminated water or urine; it ranges from mild febrile illness t…
Lesion: definition, types, causes, diagnosis and significance Lesion A lesion is any focal damage or abnormal change in the tissue of a living organism. This article explains forms, causes, clinical approach, examples across medicine and botany, and…
Leukemia: overview, types, causes, diagnosis, and treatment Leukemia Leukemia is a group of blood cancers originating in bone marrow and white blood cells. This article explains types, causes, diagnosis, treatments, prognosis, and notable distinctio…
Lewy bodies: pathology, clinical associations, and significance Lewy body Lewy bodies are abnormal intraneuronal inclusions rich in alpha-synuclein, found in Parkinson disease, dementia with Lewy bodies and related disorders; they are a neuropathological…
Light therapy: uses, mechanisms, history, and types Light therapy Overview of therapeutic light exposure: principles, common medical uses (mood, sleep, skin), equipment, safety considerations, and distinctions among bright, narrowband, and blue-l…
Linezolid: an oxazolidinone antibiotic for serious Gram‑positive infections Linezolid Linezolid is an oxazolidinone antibiotic active against many Gram‑positive pathogens, used for selected skin, soft tissue and pulmonary infections; it has important safety consider…
Liposarcoma: overview, types, diagnosis, and management Liposarcoma Liposarcoma is a rare malignant tumor of fat tissue in deep soft tissues. This article summarizes its types, clinical features, diagnosis, treatment and how it differs from benign…
List of diseases — overview, classification, and uses List of diseases An encyclopedic guide to lists of diseases: what they include, common classification schemes, historical development, practical uses, and important limitations for readers and prac…
List of common genetic disorders and how they are classified List of genetic disorders Overview of frequently encountered genetic disorders, mutation categories, inheritance patterns, examples with typical chromosomes, and diagnostic and clinical considerations.
ICD-10 codes: structure, history, organization and uses List of ICD-10 codes Overview of the International Classification of Diseases, 10th Revision (ICD-10): code format, chapter organization, history, national variants, and common uses in health statistic…
List of ICD-9 codes Overview and explanation of the ICD-9 classification: structure, history, uses, and differences from later revisions, including clinical modifications and common applications.
List of medical abbreviations Overview of common medical abbreviations: formation, examples, history, uses, risks and best practices for clear clinical communication.
List of suicide crisis lines Overview of suicide crisis lines: purpose, history, common services, how to access help, effectiveness, and distinctions among national and specialized crisis supports.
Liver cancer Overview of primary liver cancer: major types, causes and risk factors, diagnosis, treatment options, prevention strategies, and distinctions including pediatric forms.
Liver disease: causes, types, diagnosis, and management Liver disease Comprehensive overview of liver disease: anatomy and function, common types (hepatitis, fatty liver, cirrhosis, cancer), causes, signs, diagnosis, treatment, prevention, and public…
Liver failure: causes, symptoms, diagnosis and management Liver failure Comprehensive overview of liver (hepatic) failure, including types, common causes, clinical features, diagnostic approach, treatment options and prevention strategies.
Lobotomy (Leucotomy): History, Procedure, Effects and Legacy Lobotomy Lobotomy, or leucotomy, is a historical psychosurgical procedure that disrupted frontal‑brain connections to treat severe mental disorders. This article explains its methods, outco…
Lorazepam: Uses, effects, pharmacology, and precautions Lorazepam Lorazepam (Ativan) is a benzodiazepine used for anxiety, seizure control and sedation. It depresses the central nervous system; benefits, common side effects, dependence risks and…
Lumbar puncture (spinal tap): purpose, technique, risks and aftercare Lumbar puncture Lumbar puncture (spinal tap) is a procedure to obtain cerebrospinal fluid or adjust intracranial pressure. This article explains purpose, how it’s done, indications, risks, and fol…
Lung cancer: overview, types, causes, diagnosis, treatment and prevention Lung cancer Comprehensive overview of lung cancer: main types, risk factors, common symptoms, diagnostic approaches, staging, treatments including surgery, chemo, targeted and immunotherapy, a…
Lung transplant Surgical replacement of one or both diseased lungs with healthy donor lungs to treat end-stage respiratory disease; includes types, indications, risks, and outcomes.
Lupus (systemic lupus erythematosus and related conditions) Lupus Lupus is a chronic autoimmune condition in which the immune system attacks healthy tissues. This article explains types, symptoms, causes, diagnosis, treatment options, and key dis…
Lyme disease (Lyme borreliosis): causes, symptoms, diagnosis, treatment, and prevention Lyme disease Lyme disease is an infection caused by Borrelia spirochetes transmitted by ticks. This article explains its causes, stages, diagnosis, treatment options, prevention, history, and i…
