A chronic inflammatory skin condition of the pilosebaceous unit characterized by comedones, papules, pustules, nodules, and cysts. Affects 85% of adolescents but can persist into adulthood. Severe forms include nodulocystic acne and acne conglobata with risk of permanent scarring.

A neurodevelopmental disorder characterized by inattention, hyperactivity, and impulsivity. Begins in childhood and often persists into adulthood. Affects approximately 5-7% of children and 2.5-4% of adults globally. Three subtypes: predominantly inattentive, predominantly hyperactive-impulsive, and combined.

Progressive degenerative disease of the macula causing central vision loss. Leading cause of irreversible blindness in adults over 50 in developed countries. Dry (atrophic) and wet (neovascular) forms.

A chronic inflammatory arthritis primarily affecting the axial skeleton (spine and sacroiliac joints), causing pain, stiffness, and potential fusion. A form of spondyloarthritis. Strong association with HLA-B27. Onset typically in young adulthood.

A group of mental health conditions characterized by excessive fear, worry, and related behavioral disturbances. Generalized Anxiety Disorder (GAD) involves persistent, uncontrollable worry about everyday things. Most common mental health disorder.

Chronic inflammatory airway disease causing reversible bronchospasm, wheezing, dyspnea. Affects 262 million globally. Can be life-threatening during severe attacks.

The most common sustained cardiac arrhythmia, characterized by chaotic electrical activity in the atria leading to irregular ventricular response. Increases risk of stroke five-fold and heart failure. Prevalence increases with age, affecting ~10% of people over 80.

A complex neurodevelopmental condition characterized by challenges with social communication and interaction, and restricted, repetitive patterns of behavior, interests, or activities. Spectrum disorder ranging from mild to severe. Affects approximately 1-2% of population, more common in males.

Carrier state of beta-thalassemia with one normal and one mutated beta-globin gene. Mild microcytic anemia, usually asymptomatic. Important for genetic counseling as carriers can have children with thalassemia major if partner also carrier.

A mental health condition causing extreme mood swings including emotional highs (mania/hypomania) and lows (depression). Formerly called manic depression. Types I and II. Affects approximately 2.8% of adults globally.

A chronic lung condition characterized by permanent abnormal dilation and destruction of bronchial walls, leading to impaired mucus clearance, recurrent infections, and progressive lung damage. Often underdiagnosed. Can be post-infectious or associated with underlying conditions.

A clouding of the normally clear lens of the eye, leading to decreased vision. Most commonly age-related but can be congenital or secondary to other conditions. Leading cause of blindness globally but highly treatable.

Progressive, irreversible loss of kidney function over months to years. Stage 4 (eGFR 15-29 mL/min) and Stage 5/end-stage renal disease (eGFR <15 mL/min or dialysis). Requires renal replacement therapy. Leading causes: diabetes and hypertension.

A progressive inflammatory disease of the pancreas causing permanent structural damage and loss of function. Characterized by chronic abdominal pain, exocrine insufficiency (malabsorption), and endocrine insufficiency (diabetes). Most commonly caused by alcohol.

End-stage liver disease characterized by replacement of normal hepatic architecture with fibrosis and regenerative nodules. Results from chronic liver injury. Irreversible but progression can be halted.

An extremely painful primary headache disorder characterized by severe unilateral orbital, supraorbital, or temporal pain lasting 15-180 minutes, occurring in clusters (periods of frequent attacks). Known as 'suicide headache' due to intensity. More common in men.

Advanced chronic obstructive pulmonary disease (GOLD grades 3-4, FEV1 <50% predicted). Characterized by persistent respiratory symptoms and airflow limitation. Third leading cause of death globally. Severe disease significantly impairs quality of life and increases mortality.

Respiratory illness caused by SARS-CoV-2 virus. Global pandemic 2020-2023. Range from asymptomatic to severe pneumonia, ARDS, death. Long COVID affects millions.

Persistent symptoms following acute COVID-19 infection, lasting weeks to months after initial recovery. Affects multiple organ systems. Estimated 10-30% of COVID-19 survivors develop long COVID. Symptoms can be debilitating and fluctuating.

An inherited disorder of renal amino acid transport causing excessive urinary excretion of cystine and other dibasic amino acids. Cystine precipitates forming recurrent kidney stones (cystine calculi), potentially leading to renal damage.

Cognitive decline caused by impaired blood flow to the brain, typically from strokes or small vessel disease. Second most common dementia after Alzheimer's. Often coexists with Alzheimer's (mixed dementia). Stepwise progression correlating with vascular events.

Mosquito-borne viral infection caused by dengue virus (4 serotypes). Transmitted by Aedes aegypti and Aedes albopictus. 100-400 million infections annually. Can progress to severe dengue (dengue hemorrhagic fever/shock syndrome).

An autoimmune condition where the pancreas produces little or no insulin. Previously known as juvenile diabetes, it typically appears during childhood or adolescence but can develop in adults. Requires lifelong insulin therapy.

A chronic metabolic disorder characterized by high blood sugar, insulin resistance, and relative lack of insulin. The most common form of diabetes, accounting for 90-95% of cases. Often preventable and sometimes reversible with lifestyle changes.

A diabetes complication affecting the eyes, caused by damage to blood vessels in the retina. Leading cause of blindness in working-age adults. Can progress from mild non-proliferative to proliferative retinopathy with neovascularization.

A chronic, relapsing inflammatory skin condition characterized by intense itching, dry skin, and eczematous lesions. Part of the 'atopic triad' with asthma and allergic rhinitis. Affects up to 20% of children and 10% of adults. Often begins in infancy.

Chronic neurological disorder characterized by recurrent, unprovoked seizures due to excessive neuronal activity in brain. Affects 50 million people worldwide. Many types: focal, generalized, unknown onset. Often begins in childhood or after age 65.

A condition in which excess fat builds up in the liver, not due to alcohol use. The most common chronic liver disease worldwide, affecting 25% of the global population. Ranges from simple steatosis to nonalcoholic steatohepatitis (NASH) which can progress to cirrhosis.

A chronic disorder characterized by widespread musculoskeletal pain, fatigue, sleep disturbances, and cognitive difficulties. Central sensitization syndrome where pain signals are amplified. Affects 2-4% of population, predominantly women.

Inflammation of the stomach lining. Can be acute (sudden onset) or chronic (long-term). Common causes include H. pylori infection, NSAID use, and excessive alcohol consumption. Can lead to ulcers and increased stomach cancer risk if untreated.

A chronic digestive disease where stomach acid or bile irritates the food pipe lining. Occurs when the lower esophageal sphincter relaxes abnormally or weakens. Affects approximately 20% of adults in Western countries. Can lead to serious complications if untreated.

Diabetes diagnosed for the first time during pregnancy. Affects approximately 2-10% of pregnancies worldwide. Increases risk of complications for both mother and baby but usually resolves after delivery. Women with GDM have 50% lifetime risk of developing type 2 diabetes.

An intestinal infection caused by the parasite Giardia lamblia (also called Giardia intestinalis or duodenalis). Common waterborne disease causing diarrhea, gas, and stomach cramps. Most common intestinal parasitic disease in US.

A group of eye conditions damaging the optic nerve, often due to abnormally high pressure in the eye (intraocular pressure). Leading cause of irreversible blindness worldwide. Primary open-angle glaucoma most common; angle-closure glaucoma is emergency.

The most common enzyme deficiency worldwide, causing hemolytic anemia with oxidative stress. X-linked. Affects 400 million people, most commonly in malaria-endemic regions (protective against malaria). Triggers include fava beans, certain drugs, infections.

A chronic inflammatory arthritis caused by hyperuricemia and deposition of monosodium urate crystals in joints and tissues. Characterized by recurrent acute flares and progressive joint damage. Associated with metabolic syndrome, cardiovascular disease, and chronic kidney disease.

Structural abnormalities of one or more heart valves (aortic, mitral, tricuspid, pulmonic) causing stenosis (narrowing) or regurgitation (leakage). Can be congenital or acquired. Aortic stenosis most common in elderly; rheumatic heart disease prevalent in developing countries.

Rare inherited bleeding disorders caused by deficiency in clotting factor VIII (Hemophilia A) or IX (Hemophilia B/Christmas disease). X-linked recessive inheritance affecting primarily males. Characterized by prolonged bleeding after injury, surgery, or spontaneous bleeding into joints and muscles.

Viral infection causing liver inflammation, transmitted via blood. Often chronic, leading to cirrhosis and liver cancer. Curable with direct-acting antivirals (DAAs). 58 million chronically infected.

A viral infection caused by hepatitis C virus (HCV) that causes liver inflammation, potentially leading to cirrhosis, hepatocellular carcinoma, and liver failure. Chronic infection develops in 75-85% of acute cases. Curable with direct-acting antivirals.

A condition where the thyroid gland produces too much thyroid hormone (T3 and T4). Accelerates the body's metabolism, causing unintentional weight loss, rapid heartbeat, sweating, and nervousness. Graves' disease is the most common cause.

A condition where the thyroid gland doesn't produce enough thyroid hormones. Slows down many of the body's functions. Hashimoto's thyroiditis is the most common cause in developed countries. Can occur at any age but is more common in older women.

Viral respiratory infection caused by influenza A and B viruses. Annual epidemics causing significant morbidity and mortality. Vaccine composition updated yearly.

A common functional gastrointestinal disorder affecting the large intestine, characterized by abdominal pain and altered bowel habits (diarrhea, constipation, or both). Brain-gut interaction disorder without structural abnormalities. Affects 10-15% of global population.

Recurrent formation of solid mineral deposits in the kidneys, causing severe pain and potential kidney damage. Affects 1 in 10 people; 50% recurrence rate within 5-10 years without preventive measures. Most common type: calcium oxalate.

A myeloproliferative neoplasm characterized by the Philadelphia chromosome (t(9;22)) creating the BCR-ABL fusion gene, leading to constitutively active tyrosine kinase. Chronic phase is indolent; without treatment progresses to accelerated phase and blast crisis.

The progressive form of non-alcoholic fatty liver disease (NAFLD), characterized by hepatic steatosis with inflammation and hepatocyte injury, with or without fibrosis. Can progress to cirrhosis and hepatocellular carcinoma. Now called MASH (metabolic dysfunction-associated steatohepatitis).

Malignant tumor arising from lung tissue. Leading cause of cancer death worldwide (1.8 million deaths/year). Two main types: non-small cell (NSCLC, 85%) and small cell (SCLC, 15%). Strongly associated with smoking but affects non-smokers too.

A common but serious mood disorder causing persistent feelings of sadness and loss of interest. Affects approximately 280 million people worldwide, leading cause of disability globally. Can occur at any age.

Parasitic disease transmitted by infected Anopheles mosquitoes. Caused by Plasmodium species (falciparum, vivax, ovale, malariae, knowlesi). Major public health problem in tropical regions, causing ~600,000 deaths annually, mostly children under 5.

A malignant tumor of melanocytes, the pigment-producing cells of the skin. The most serious form of skin cancer with high metastatic potential. Incidence rising globally, particularly in fair-skinned populations. Early detection critical for survival.

A disorder of the inner ear causing episodes of vertigo, fluctuating hearing loss, tinnitus, and aural fullness. Caused by abnormal fluid buildup in the inner ear (endolymphatic hydrops). Affects approximately 12-30 per 100,000 people.

A life-threatening infection of the meninges (membranes surrounding the brain and spinal cord) caused by bacteria. Medical emergency requiring immediate antibiotic treatment. Can cause brain damage, hearing loss, and death. Vaccines available for some types.

A primary headache disorder characterized by recurrent attacks of moderate to severe throbbing pain, usually on one side of the head, often accompanied by nausea, vomiting, and sensitivity to light and sound. Can last 4-72 hours. Second most disabling condition worldwide.

A contagious disease most commonly caused by Epstein-Barr virus (EBV). Characterized by fever, sore throat, swollen lymph nodes, and fatigue. Often called 'mono' or 'kissing disease' due to transmission via saliva. Most common in adolescents and young adults.

Complex chronic disease characterized by excessive adipose tissue accumulation (BMI >=35). Associated with metabolic dysfunction, inflammation, and increased morbidity/mortality. Now recognized as relapsing-remitting disease requiring long-term management.

A chronic mental health disorder characterized by uncontrollable, recurring thoughts (obsessions) and behaviors (compulsions) that the person feels compelled to repeat. Often time-consuming and interferes with daily life.

A systemic skeletal disease characterized by low bone mass and microarchitectural deterioration of bone tissue, leading to increased bone fragility and fracture risk. Often called the 'silent disease' because bone loss occurs without symptoms until fracture occurs.

Open sores that develop on the inside lining of the stomach (gastric ulcers) and the upper portion of the small intestine (duodenal ulcers). Most common cause is H. pylori infection or NSAID use. Affects approximately 4% of the global population.

Infection causing inflammation of lung air sacs (alveoli). Can be bacterial, viral, or fungal. Leading cause of death in children worldwide and serious illness in elderly.

A common hormonal disorder affecting women of reproductive age, characterized by hyperandrogenism, ovulatory dysfunction, and polycystic ovaries. Leading cause of infertility. Associated with metabolic syndrome and increased cardiovascular risk.

A chronic immune-mediated inflammatory skin disease characterized by well-demarcated, erythematous plaques with silvery scale. Affects 2-3% of global population. Associated with psoriatic arthritis, cardiovascular disease, and metabolic syndrome.

A mental health condition triggered by experiencing or witnessing a terrifying event. Characterized by intrusive memories, avoidance, negative changes in thinking and mood, and hyperarousal. Can develop after combat, assault, accidents, or natural disasters.

The most common chronic rheumatic disease in children, characterized by persistent joint inflammation lasting >6 weeks in children <16 years. Multiple subtypes including oligoarticular, polyarticular, and systemic (Still's disease). Can cause permanent joint damage and growth abnormalities.

Severe chronic mental disorder characterized by disruptions in thought processes, perceptions, emotional responsiveness, and social interactions. Involves positive symptoms (hallucinations, delusions), negative symptoms (apathy, withdrawal), and cognitive impairment.

A life-threatening organ dysfunction caused by a dysregulated host response to infection. Medical emergency with high mortality. Septic shock is a subset with circulatory and cellular/metabolic dysfunction. Leading cause of death in hospitals.

Carrier state of sickle cell disease (HbAS), usually asymptomatic but associated with rare complications including exercise-related sudden death, rhabdomyolysis, renal medullary carcinoma, and splenic infarction at high altitude.

A sleep-related breathing disorder characterized by recurrent episodes of complete or partial upper airway obstruction during sleep, causing apneas or hypopneas. Leads to fragmented sleep, daytime sleepiness, and cardiovascular complications. Often undiagnosed.

A bacterial infection of the throat and tonsils caused by group A Streptococcus (GAS). Common in children but can affect all ages. If untreated, can lead to serious complications including rheumatic fever and post-streptococcal glomerulonephritis.

Acute cerebral infarction caused by interruption of blood supply to the brain, typically from thrombosis or embolism. The most common type of stroke (85% of all strokes). Time-critical emergency requiring rapid intervention. Leading cause of disability worldwide.

A parasitic disease caused by Toxoplasma gondii. Most people experience no symptoms, but can cause serious complications in pregnant women and immunocompromised individuals. Transmitted through undercooked meat, cat feces, and mother-to-child.

Bacterial infection caused by Mycobacterium tuberculosis, primarily affecting lungs but can involve any organ. Leading infectious cause of death worldwide. Latent infection common; active disease in 5-10% of infected.

Autoimmune destruction of pancreatic beta cells causing absolute insulin deficiency. Requires lifelong exogenous insulin. Onset typically in childhood/adolescence but can occur at any age.

Progressive metabolic disorder characterized by insulin resistance and relative insulin deficiency. Accounts for 90-95% of diabetes cases. Strongly associated with obesity and sedentary lifestyle.

An autoimmune disorder characterized by loss of melanocytes resulting in depigmented patches of skin and hair. Affects 0.5-2% of global population. Can be segmental (limited) or non-segmental (generalized). Associated with other autoimmune diseases.

A group of hereditary disorders affecting tyrosine metabolism. Type I most severe, caused by fumarylacetoacetate hydrolase deficiency. Causes liver failure, renal dysfunction, and neurologic crises. Types II and III less severe with mainly skin/eye or developmental symptoms.

A group of metabolic diseases characterized by high blood sugar levels over a prolonged period. Types include Type 1 (autoimmune), Type 2 (insulin resistance), and gestational diabetes. Leading cause of blindness, kidney failure, and amputations.

A rare chronic vasculitis causing recurrent mouth ulcers, genital ulcers, eye inflammation, and skin lesions. Can affect blood vessels of all sizes. Associated with HLA-B51 in some populations. Silk Road disease.

A common bacterial infection affecting any part of the urinary system including kidneys, ureters, bladder, and urethra. Most commonly affects the lower urinary tract (bladder and urethra). Women are at greater risk than men. Recurrent UTIs affect 20-30% of women.

The involuntary loss of bladder control, ranging from occasional leakage to complete inability to hold urine. Affects twice as many women as men, especially after pregnancy, childbirth, and menopause. Not a normal part of aging but becomes more common with age.

The consistent inability to achieve or maintain an erection sufficient for satisfactory sexual performance. Affects approximately 50% of men aged 40-70. Often an early indicator of cardiovascular disease. Can significantly impact quality of life and relationships.

A chronic condition causing bladder pressure, bladder pain, and sometimes pelvic pain. Part of a spectrum of painful bladder syndromes. More common in women. Symptoms often mimic UTI but urine cultures are negative. Cause is unknown but may involve bladder lining defects.

A connective tissue disorder characterized by the development of fibrous scar tissue (plaque) inside the penis, causing curved, painful erections. Affects 3-9% of men, most commonly between ages 45-60. Can significantly impact sexual function and psychological well-being.

A collection of fluid in the scrotum around the testicle, causing swelling. Common in newborns (usually resolves within first year) and older men. Typically painless but can cause discomfort due to swelling. Two types: communicating (patent processus vaginalis) and non-communicating.

Enlargement of the veins within the loose bag of skin holding the testicles (scrotum), similar to varicose veins in legs. Occurs in 15% of men, most commonly on left side due to venous anatomy. Leading cause of correctable male infertility.

A surgical emergency caused by twisting of the spermatic cord, cutting off blood supply to the testicle. Most common in adolescent males (ages 12-18) but can occur at any age. Requires immediate treatment within 6 hours to save the testicle. Affects 1 in 4,000 males under 25 annually.

Inflammation of the epididymis, the coiled tube at the back of the testicle that stores and carries sperm. Most common cause of acute scrotal pain in adults. Can be caused by bacterial infection (sexually transmitted or urinary pathogens) or non-infectious inflammation.

Inflammation of the urethra, the tube that carries urine from the bladder out of the body. Most commonly caused by sexually transmitted infections (chlamydia, gonorrhea) but can also be non-infectious. Affects both men and women, though symptoms are more prominent in men.

An anxiety disorder characterized by recurrent unexpected panic attacks—sudden periods of intense fear that reach a peak within minutes. Affects 2-3% of adults annually. Often associated with agoraphobia (fear of situations where escape might be difficult).

A chronic mental health condition characterized by intense, persistent fear of being watched and judged by others. Goes beyond ordinary shyness. Affects approximately 7% of adults. Often begins in childhood or adolescence. Can severely impact social and occupational functioning.

A highly contagious, vaccine-preventable liver infection caused by hepatitis A virus. Transmitted through fecal-oral route, typically via contaminated food/water or close contact. Usually self-limited with full recovery and no chronic infection. Common in areas with poor sanitation.

A liver disease caused by hepatitis E virus, transmitted primarily through contaminated water. Similar to hepatitis A in transmission and course. Most common in South Asia and East Asia. Genotypes 1 and 2 cause large waterborne outbreaks; genotypes 3 and 4 are zoonotic. High mortality in pregnant women (15-25%).

A bulge or ballooning in the wall of the aorta, the body's main artery. Can occur in the chest (thoracic) or abdomen (abdominal). Life-threatening if it ruptures. Often asymptomatic until complications occur. Associated with atherosclerosis, hypertension, and genetic conditions.

Narrowing of the aortic valve opening, restricting blood flow from the heart to the aorta. Most commonly caused by age-related calcification, congenital bicuspid valve, or rheumatic fever. Progressive disease; severe cases require valve replacement.

A condition where the mitral valve doesn't close tightly, causing blood to flow backward into the left atrium when the heart contracts. Can be primary (valve problem) or secondary (heart enlargement). Leads to heart enlargement and heart failure if severe.

Inflammation of the pericardium, the thin sac surrounding the heart. Causes chest pain and can lead to fluid accumulation (pericardial effusion) or heart compression (cardiac tamponade). Often idiopathic but can follow viral infections or autoimmune conditions.

Inflammation of the heart muscle (myocardium) that can weaken the heart and affect its electrical system. Often follows viral infections but can be autoimmune or drug-related. Can cause heart failure, arrhythmias, or sudden cardiac death.

A genetic condition causing abnormal thickening of the heart muscle, particularly the left ventricle. Most common cause of sudden cardiac death in young athletes. Can obstruct blood flow (obstructive HCM) or not (non-obstructive).

Narrowing of peripheral arteries, usually in the legs, due to atherosclerosis. Reduces blood flow to limbs causing pain with walking (claudication). Strong marker for cardiovascular disease elsewhere. Increases risk of heart attack and stroke.

Infection of the inner lining of the heart chambers and valves. Usually caused by bacteria entering the bloodstream. Life-threatening condition requiring prolonged antibiotic therapy and sometimes surgery. Risk increased in those with prosthetic valves or congenital heart disease.

Buildup of abnormal amyloid protein in the heart tissue causing stiffening and restrictive cardiomyopathy. Two main types: ATTR (transthyretin, age-related or hereditary) and AL (light chain, associated with multiple myeloma). Increasingly recognized cause of heart failure with preserved ejection fraction.

A blockage in one of the pulmonary arteries in the lungs, usually caused by blood clots that travel from deep veins in the legs (DVT). Life-threatening condition requiring immediate treatment. Can cause sudden death if massive.

Accumulation of excess fluid in the pleural space between the lungs and chest wall. Can be caused by heart failure, pneumonia, cancer, pulmonary embolism, or liver/kidney disease. Symptoms depend on amount and rate of fluid accumulation.

A pus-filled cavity in the lung surrounded by inflamed tissue, usually caused by bacterial infection. Often follows aspiration pneumonia. Associated with poor dental hygiene, alcoholism, or swallowing disorders. Modern antibiotics have reduced incidence significantly.

Collapsed lung due to air leaking into the space between the lung and chest wall. Can be spontaneous (no obvious cause), traumatic (injury), or tension (life-threatening). Primary spontaneous occurs in tall, thin young men. Requires prompt treatment.

A breathing disorder in obese people where poor breathing leads to too much carbon dioxide and too little oxygen in the blood. Often overlaps with obstructive sleep apnea. Can lead to pulmonary hypertension, heart failure, and early death if untreated.

Cancer of the voice box (larynx), most commonly squamous cell carcinoma. Strongly associated with tobacco and alcohol use. Hoarseness is the most common early symptom. Can affect voice, swallowing, and breathing depending on location.

Cancer arising from the nasopharynx, the area behind the nose and above the back of the throat. Strongly associated with Epstein-Barr virus (EBV), genetic factors, and certain dietary habits (salted fish). Common in Southeast Asia and North Africa.

Also known as delta hepatitis, caused by the hepatitis D virus (HDV) which requires hepatitis B virus to replicate. The most severe form of viral hepatitis with rapid progression to cirrhosis. Occurs as coinfection (with HBV) or superinfection (in chronic HBV).

Progressive form of non-alcoholic fatty liver disease (NAFLD) characterized by liver inflammation and damage in people who drink little or no alcohol. Can progress to cirrhosis, liver failure, and liver cancer. Associated with obesity, diabetes, and metabolic syndrome.

Sudden inflammation of the pancreas, usually mild and self-limiting but can be life-threatening. Most commonly caused by gallstones or alcohol. Presents with severe abdominal pain. Can lead to pancreatic necrosis, organ failure, or pseudocysts.

Inability to fully digest lactose, the sugar in milk and dairy products, due to deficiency of lactase enzyme in the small intestine. Very common worldwide, especially in certain ethnic groups. Not dangerous but can cause uncomfortable symptoms.

Narrowing of the esophagus causing difficulty swallowing (dysphagia). Most commonly caused by chronic acid reflux (GERD) leading to scar tissue formation. Other causes include radiation, eosinophilic esophagitis, cancer, and ingestion of caustic substances.

A cluster of conditions including increased blood pressure, high blood sugar, excess body fat around the waist, and abnormal cholesterol levels. Occurring together, they increase risk of heart disease, stroke, and type 2 diabetes. Very common in developed countries.

A group of genetic disorders causing brittle bones that break easily. Caused by defects in type I collagen. Range from mild (few fractures) to severe (lethal in infancy). Also known as brittle bone disease. Can affect teeth, hearing, and connective tissue.

A rare genetic disorder causing episodes of muscle weakness or paralysis triggered by low potassium levels. Episodes often occur during rest after exercise or high-carbohydrate meals. Muscles work normally between attacks. Can lead to permanent weakness over time.

A chronic neurological disorder affecting the brain's ability to control sleep-wake cycles. Characterized by excessive daytime sleepiness and cataplexy (sudden muscle weakness triggered by emotions). Often caused by loss of hypocretin-producing neurons. Onset typically in adolescence.

A neurological disorder causing uncomfortable sensations in the legs and an irresistible urge to move them. Symptoms worse at rest and in the evening/night. Significantly disrupts sleep. Associated with iron deficiency, kidney disease, pregnancy, and certain medications.

One of the most common causes of vertigo, triggered by specific changes in head position. Caused by tiny calcium crystals (canaliths) becoming dislodged in the inner ear. Brief, intense episodes of spinning sensation lasting less than a minute.

A tear in one or more of the four rotator cuff tendons in the shoulder (supraspinatus, infraspinatus, teres minor, subscapularis). Can occur from acute injury or degenerative changes with aging. Causes shoulder pain and weakness, especially with overhead activities.

Narrowing of the spaces within the spine, putting pressure on the spinal cord and nerves. Most commonly affects the lower back (lumbar) and neck (cervical). Causes pain, numbness, and muscle weakness. Usually age-related degenerative changes.

When the soft inner material of a spinal disc in the lower back pushes through the tough outer layer, irritating nearby nerves. Commonly called a slipped or ruptured disc. Most common in ages 30-50. Most improve with conservative treatment within 6 weeks.

Inflammation of the Achilles tendon, the large tendon connecting the calf muscles to the heel bone. Common in runners and athletes who have suddenly increased training intensity. Causes pain and stiffness along the back of the leg near the heel.

Inflammation of the plantar fascia, a thick band of tissue running across the bottom of the foot connecting the heel bone to the toes. Causes stabbing heel pain, especially with first steps in the morning. Most common cause of heel pain.

Persistent or recurrent infection of the kidneys causing progressive scarring and damage. Usually results from repeated acute pyelonephritis, often due to urinary tract obstruction or vesicoureteral reflux. Can lead to chronic kidney disease and end-stage renal disease.

Narrowing of one or both renal arteries reducing blood flow to the kidneys. Causes hypertension that can be difficult to control and can lead to kidney damage. Usually caused by atherosclerosis (older patients) or fibromuscular dysplasia (younger women).

A kidney disorder where the kidneys cannot concentrate urine due to resistance to antidiuretic hormone (ADH/vasopressin). Causes excessive thirst and excretion of large amounts of dilute urine. Can be inherited (genetic) or acquired (lithium, other medications).

A condition characterized by sudden, involuntary contraction of the bladder muscle causing urgency to urinate, often with frequency and nocturia. May or may not involve urge incontinence. Very common, especially with aging, but not a normal part of aging.

Cancer that starts in the kidneys, most commonly renal cell carcinoma (RCC). Often discovered incidentally on imaging. Associated with smoking, obesity, and hypertension. Can be cured if caught early but has poor prognosis if metastatic.

A congenital condition in males where the opening of the urethra is located on the underside of the penis rather than at the tip. One of the most common birth defects of the male genitalia. Varies in severity based on location of urethral opening.

A fluid-filled sac in the epididymis, the coiled tube behind each testicle that stores and carries sperm. Very common and benign. Usually painless and discovered during self-exam. Can vary in size. Different from testicular cancer.

A chronic eye condition where fluid in the eye doesn't drain properly, causing increased pressure that damages the optic nerve. The most common type of glaucoma. Called the 'silent thief of sight' because it causes gradual vision loss without early symptoms.

Clouding of the eye's natural lens that occurs with aging. The most common type of cataract and a leading cause of vision impairment worldwide. Develops gradually over years. Surgery is the only effective treatment and is highly successful.

Inflammation of the eyelids causing red, irritated, itchy eyelids and dandruff-like scales on eyelashes. Very common and chronic condition. Associated with dry eye, meibomian gland dysfunction, and sometimes skin conditions like rosacea or dandruff.

Blood pooling in the anterior chamber of the eye between the cornea and iris, usually due to trauma. Can cause increased eye pressure and vision loss. Medical emergency requiring prompt evaluation and management to prevent complications like glaucoma and corneal staining.

Misalignment of the eyes in adults, either persistent from childhood or newly acquired. Can cause double vision, eye strain, and difficulty with depth perception. New-onset in adults often indicates underlying neurological or medical condition requiring evaluation.

Overproduction of thyroid hormones causing accelerated metabolism. Most commonly caused by Graves' disease, toxic nodular goiter, or thyroiditis. Affects multiple body systems and requires treatment to prevent serious complications like heart problems and osteoporosis.

A medical emergency occurring when blood flow to the heart is severely reduced or blocked, causing heart muscle damage. Usually caused by a blood clot forming in a coronary artery already narrowed by atherosclerosis. Time-critical condition requiring immediate treatment to minimize heart damage.

A common bacterial skin infection affecting the deeper layers of skin and subcutaneous tissue. Usually caused by Streptococcus or Staphylococcus bacteria entering through breaks in the skin. Can spread rapidly and become life-threatening if not treated promptly.

A condition where small pouches (diverticula) form and bulge outward through weak spots in the colon wall. Very common in adults over 60 in developed countries. Usually asymptomatic but can lead to diverticulitis (inflammation) or bleeding. Associated with low-fiber Western diet.

A pregnancy complication characterized by high blood pressure and signs of damage to other organ systems, typically liver and kidneys. Usually begins after 20 weeks of pregnancy. Can lead to serious complications for both mother and baby including eclampsia (seizures). Leading cause of maternal and perinatal morbidity worldwide.

A potentially life-threatening condition where a fertilized egg implants and grows outside the main cavity of the uterus, most commonly in a fallopian tube. The pregnancy cannot proceed normally and can cause the fallopian tube to rupture, leading to severe internal bleeding. Requires immediate medical intervention.

A chronic inflammatory lung disease causing obstructed airflow from the lungs. Includes emphysema (destruction of lung air sacs) and chronic bronchitis (inflammation of bronchial tubes). Progressive disease that makes breathing increasingly difficult over time. Primarily caused by smoking.

A condition where bone mineral density is lower than normal but not low enough to be classified as osteoporosis. Considered a precursor to osteoporosis and increases fracture risk compared to normal bone density. Often asymptomatic until a fracture occurs.

A parasitic disease caused by the nematode worm Onchocerca volvulus, transmitted through the bites of infected blackflies. Leading cause of infectious blindness worldwide. Affects approximately 20-25 million people, primarily in sub-Saharan Africa. WHO goal is elimination by 2030.

A parasitic disease caused by Leishmania protozoa, transmitted by sandfly bites. Three main forms: cutaneous (skin sores), mucocutaneous (destruction of mucous membranes), and visceral (affects organs, fatal if untreated). Affects 1-2 million people annually, with 350 million at risk in 98 countries.

A rare large vessel vasculitis affecting the aorta and its major branches, causing vessel wall inflammation, stenosis, occlusion, and aneurysm formation. Primarily affects young women of Asian descent. Called 'pulseless disease' because pulses may be absent. One of the most common vasculitides in Asia.

A viral respiratory illness caused by Middle East Respiratory Syndrome Coronavirus (MERS-CoV). First reported in Saudi Arabia in 2012. Transmitted from camels to humans and person-to-person in close contact. Case fatality rate approximately 35%. Most cases in Arabian Peninsula.

A complex, chronic disorder characterized by extreme fatigue that cannot be explained by any underlying medical condition and does not improve with rest. Associated with post-exertional malaise, cognitive impairment, and orthostatic intolerance.

An infection of the female reproductive organs, usually caused by sexually transmitted bacteria spreading from the vagina to uterus, fallopian tubes, or ovaries. Affects approximately 4.4% of women of reproductive age. Leading preventable cause of infertility and ectopic pregnancy.

Inflammation of the vagina that can result in discharge, itching and pain. The most common types are bacterial vaginosis, yeast infections, and trichomoniasis. Affects millions of women annually and is one of the most common reasons for gynecologic visits.

A chronic pain condition affecting the vulva, characterized by burning, stinging, irritation, or rawness. Affects up to 16% of women. The cause is unknown and diagnosis is often delayed. Significantly impacts quality of life and sexual function.

Abnormally heavy or prolonged menstrual bleeding affecting up to 25% of women. Can cause anemia and significantly impact quality of life. Often caused by hormonal imbalances, uterine fibroids, or bleeding disorders.

A combination of physical and emotional symptoms that occur 1-2 weeks before menstruation. Affects up to 90% of women of reproductive age. Severe form (PMDD) affects 3-8% and causes significant functional impairment.

Persistent or recurrent genital pain that occurs just before, during, or after intercourse. Affects up to 20% of women. Can have physical or psychological causes. Significantly impacts sexual health and relationships.

A neurodevelopmental disorder characterized by persistent patterns of inattention, hyperactivity, and impulsivity. Affects approximately 5-7% of children and 2.5-5% of adults globally. Often persists into adulthood and can significantly impact academic, occupational, and social functioning.

A condition characterized by low levels of vitamin B12, leading to megaloblastic anemia and potential neurological complications. Affects approximately 6% of people under 60 and up to 20% of those over 60. Can cause irreversible nerve damage if untreated.

Liver damage caused by excessive alcohol consumption, ranging from fatty liver to alcoholic hepatitis and cirrhosis. A leading cause of liver disease worldwide. Risk increases with amount and duration of alcohol use. Can be reversible in early stages.