Medical Glossary

A functional lower-extremity performance test that counts full sit-to-stand repetitions completed in 30 seconds.

A rapid delirium screening tool (0-12) based on alertness, cognition, attention, and acute/fluctuating change; scores of 4 or more commonly suggest possible delirium.

A 6-domain observational pain scale (0-18) designed for people with severe or end-stage dementia, using behavior- and physiology-based pain indicators.

A 10-item brief cognitive screening questionnaire used in older adults; lower totals indicate greater cognitive concern.

Acromegaly is a rare, slowly progressive endocrine disorder caused by chronic hypersecretion of growth hormone (GH) after fusion of the epiphyseal growth plates in adulthood (before epiphyseal fusion, excess GH causes gigantism). In approximately 95% of cases, the cause is a GH-secreting pituitary adenoma (somatotroph adenoma). GH stimulates the liver to produce insulin-like growth factor 1 (IGF-1), which mediates most of GH's effects and has a longer half-life, making IGF-1 the preferred screening and monitoring marker. Symptoms develop insidiously over years, often with a delay of 8-10 years before diagnosis. Somatic changes include enlargement of the hands, feet, and skull; coarsening of facial features (frontal bossing, jaw prognathism, widened nose); skin thickening; and hyperhidrosis. Systemic complications are the primary determinants of mortality and morbidity: cardiovascular disease (biventricular hypertrophy, hypertension, heart failure—the leading cause of premature death), diabetes mellitus (GH is insulin-antagonistic; impaired glucose tolerance in 30-50%, overt diabetes in 20-30%), sleep apnea (in 50-80%), colon polyps and increased colorectal cancer risk, joint disease (osteoarthritis), and carpal tunnel syndrome. Compression of local structures by the pituitary tumor can cause headaches, bitemporal hemianopia, and hypopituitarism. Diagnosis: elevated age-matched IGF-1 and failure to suppress GH below 1 ng/mL during a 75g oral glucose tolerance test. Treatment: transsphenoidal adenomectomy for eligible patients; somatostatin analogs (octreotide, lanreotide) for residual or recurrent disease; pegvisomant (GH receptor antagonist) for refractory cases; radiation for treatment-resistant tumors.

Acute kidney injury (AKI), previously called acute renal failure, is a sudden decrease in kidney function occurring over hours to days, characterized by rising serum creatinine, reduced urine output (oliguria), or both, resulting in accumulation of waste products and inability to maintain fluid and electrolyte homeostasis. According to the 2012 KDIGO (Kidney Disease: Improving Global Outcomes) criteria, AKI is diagnosed by any one of three criteria: an absolute increase in serum creatinine of at least 0.3 mg/dL (26.5 µmol/L) within 48 hours, a 50% increase in serum creatinine from baseline within 7 days, or urine volume less than 0.5 mL/kg/hour for at least 6 hours. Severity is staged 1 through 3 based on magnitude of creatinine rise or degree of oliguria, with stage 3 representing the most severe (creatinine increased to >3 times baseline or >4.0 mg/dL, urine output <0.3 mL/kg/hour for ≥24 hours, anuria for ≥12 hours, or initiation of renal replacement therapy). Patients with both oliguria and azotemia, or in whom these impairments persist, are more likely to have worse disease and outcomes. AKI causes are traditionally categorized into three types: prerenal (most common, approximately 60-70% of cases) results from reduced blood flow to the kidneys without direct kidney damage, due to hypovolemia (dehydration, bleeding, third-spacing), decreased effective circulating volume (heart failure, cirrhosis, sepsis), or renal artery obstruction; intrinsic renal or intrarenal (25-40% of cases) involves direct damage to kidney structures, most commonly acute tubular necrosis (ATN) from ischemia or nephrotoxins (aminoglycosides, NSAIDs, contrast dye, cisplatin), but also acute interstitial nephritis (drug hypersensitivity), glomerulonephritis, or vascular injury; and postrenal (5-10% of cases) results from obstruction of urine outflow, including bilateral ureteral obstruction (kidney stones, retroperitoneal fibrosis, malignancy) or bladder outlet obstruction (benign prostatic hyperplasia, urethral stricture, neurogenic bladder). Distinguishing prerenal from intrinsic AKI is clinically important because prerenal AKI is typically reversible with volume resuscitation, while ATN often requires supportive care and time for tubular regeneration. The fractional excretion of sodium (FENa) helps differentiate: FENa <1% suggests prerenal azotemia (kidneys avidly reabsorb sodium to conserve volume), while FENa >2% suggests intrinsic kidney disease like ATN (damaged tubules cannot reabsorb sodium effectively). Complications of AKI include volume overload and pulmonary edema, hyperkalemia (potentially causing life-threatening arrhythmias), metabolic acidosis, uremia (causing nausea, confusion, pericarditis), and electrolyte disturbances. Management focuses on identifying and treating the underlying cause (volume resuscitation for prerenal causes, stopping nephrotoxic drugs, relieving obstruction for postrenal causes), avoiding additional kidney injury (dose-adjust medications, avoid nephrotoxins, maintain adequate perfusion), carefully managing fluids and electrolytes, and initiating renal replacement therapy (dialysis) for life-threatening complications including refractory hyperkalemia, severe metabolic acidosis, uremic complications (pericarditis, encephalopathy), or volume overload unresponsive to diuretics. Many patients with AKI recover kidney function, though recovery time varies from days to weeks depending on severity and cause. However, AKI is associated with increased risk of developing chronic kidney disease and progression to end-stage renal disease, even after apparent recovery.

ARDS is a severe, life-threatening form of respiratory failure characterized by widespread inflammation in the lungs, leading to alveolar flooding, impaired gas exchange, and low lung compliance. The Berlin Definition (2012) classifies ARDS by the PaO2/FiO2 (P/F) ratio measured with PEEP of at least 5 cmH2O: mild (P/F 200-300 mmHg), moderate (P/F 100-200 mmHg), and severe (P/F below 100 mmHg). ARDS onset must occur within 1 week of a known clinical insult, bilateral opacities must be present on chest imaging, and respiratory failure must not be fully explained by cardiac failure or fluid overload. Common causes include sepsis (most common, approximately 40% of ARDS cases), aspiration pneumonitis, pneumonia, trauma, massive transfusion, and pancreatitis. Pathophysiologically, the exudative phase involves neutrophil-mediated endothelial and epithelial injury, increased vascular permeability, and flooding of alveoli with protein-rich edema. ICU mortality ranges from 35-40% for severe ARDS. The cornerstone of management is lung-protective ventilation: low tidal volumes (6 mL/kg ideal body weight), plateau pressure below 30 cmH2O, and PEEP titration to maintain alveolar recruitment. Prone positioning for 16 or more hours per day reduces mortality in moderate-severe ARDS. Neuromuscular blockade, dexamethasone, and conservative fluid strategy provide additional benefit in select patients.

Damage to the kidney tubules causing acute kidney injury. Usually results from prolonged ischemia (low blood flow) or nephrotoxins (contrast dye, certain medications). Characterized by FENa >2% and muddy brown casts in urine.

An 8-item informant-based cognitive change screen scored 0-8; scores of 2 or higher commonly indicate a positive cognitive impairment signal.

Adrenal insufficiency (AI) is a condition in which the adrenal glands produce insufficient cortisol and, in primary forms, also aldosterone, resulting in life-threatening if untreated. Primary adrenal insufficiency (Addison's disease) results from destruction of the adrenal cortex itself; in developed countries, autoimmune adrenalitis is the most common cause (with anti-21-hydroxylase antibodies serving as diagnostic markers), while tuberculosis remains the leading cause globally. Secondary AI results from pituitary or hypothalamic disorders reducing ACTH stimulation; tertiary AI results from prolonged exogenous glucocorticoid use suppressing the HPA axis (the most common cause worldwide, affecting any patient using more than 20 mg prednisone equivalent for over 3 weeks). Clinical features of chronic AI: fatigue, weight loss, anorexia, nausea, myalgias, salt craving, postural hypotension, and in primary AI only—hyperpigmentation (from elevated ACTH/MSH) and hyponatremia with hyperkalemia (from aldosterone deficiency). Adrenal crisis is a life-threatening emergency precipitated by physiological stress (illness, surgery, trauma) in a patient with unrecognized or undertreated AI, manifesting as severe hypotension, vomiting, abdominal pain, altered consciousness, and severe hyponatremia; immediate IV hydrocortisone (100 mg bolus) is life-saving. Diagnosis uses morning cortisol (below 3 mcg/dL strongly suggests AI), ACTH stimulation test (250 mcg cosyntropin, peak cortisol below 18-20 mcg/dL), and plasma ACTH to distinguish primary (elevated) from secondary/tertiary (low/normal). Treatment: hydrocortisone replacement (15-20 mg/day split doses, mimicking diurnal cortisol rhythm), fludrocortisone for primary AI, and mandatory stress-dosing (double to triple usual dose) during illness or surgery. Patients should carry medical alert identification and emergency hydrocortisone injection.

A brief adult ADHD symptom screening questionnaire; Part A uses 6 items to flag patients who may need full diagnostic ADHD evaluation.

A five-item risk score for upper gastrointestinal bleeding mortality: Albumin low, INR high, altered Mental status, low Systolic pressure, and age 65 years or older.

Albumin is the most abundant protein in human blood plasma, accounting for approximately 50-60% of total plasma protein, and is synthesized exclusively by the liver at a rate of about 10-15 grams per day. Normal serum albumin levels range from 3.5 to 5.0 g/dL (35-50 g/L). Albumin serves multiple critical functions: it maintains oncotic pressure (the osmotic pressure exerted by proteins that keeps fluid in the vascular space rather than leaking into tissues), transports various substances including hormones, fatty acids, bilirubin, calcium, and many medications (highly protein-bound drugs like warfarin and phenytoin bind primarily to albumin), provides nutritional reserves, and has antioxidant and anti-inflammatory properties. Low albumin (hypoalbuminemia, <3.5 g/dL) can result from decreased synthesis (chronic liver disease, malnutrition, inflammation), increased loss (nephrotic syndrome with urinary protein losses >3.5 g/day, protein-losing enteropathy, severe burns, large wounds), increased degradation, or dilution (fluid overload, pregnancy). Hypoalbuminemia has significant clinical consequences: reduced oncotic pressure leads to edema (swelling) and potentially ascites (abdominal fluid accumulation); altered drug pharmacokinetics occur because medications normally bound to albumin circulate in higher free concentrations, potentially causing toxicity at usual doses; and hypoalbuminemia is a strong predictor of poor outcomes—low albumin is associated with increased mortality, longer hospital stays, and higher complication rates across numerous conditions. Severe hypoalbuminemia (<2.5 g/dL) causes significant peripheral edema, ascites, and potentially pulmonary edema or pleural effusions as fluid shifts from the vascular space into tissues. Albumin levels are incorporated into several prognostic scoring systems: the Child-Pugh score for cirrhosis severity includes albumin as one of five criteria (points assigned for albumin <3.5 g/dL, with additional points if <2.8 g/dL), and the serum-ascites albumin gradient (SAAG, calculated as serum albumin minus ascitic fluid albumin) distinguishes portal hypertension-related ascites (SAAG ≥1.1 g/dL) from other causes (SAAG <1.1 g/dL). Because albumin binds approximately 40% of serum calcium, total calcium measurements can be misleadingly low in patients with hypoalbuminemia; corrected calcium calculations adjust for this by adding 0.8 mg/dL to the total calcium for each 1 g/dL the albumin is below 4.0 g/dL. Albumin has a relatively long half-life of about 20 days, so levels change slowly; this makes albumin useful for assessing chronic nutritional status or liver synthetic function but less useful for acute changes. Treatment of hypoalbuminemia focuses on addressing the underlying cause (improving nutrition, treating liver disease, reducing proteinuria in kidney disease) rather than albumin infusions, which provide only temporary benefit and are generally reserved for specific situations like large-volume paracentesis, hepatorenal syndrome, or spontaneous bacterial peritonitis treatment.

Alcohol use disorder is a chronic relapsing condition characterized by compulsive alcohol use, loss of control over intake, and negative emotional states when not drinking. DSM-5 defines AUD based on meeting 2 or more of 11 criteria within a 12-month period, including drinking more than intended, unsuccessful attempts to cut down, cravings, tolerance, withdrawal, and continued use despite problems. Severity is categorized as mild (2-3 criteria), moderate (4-5 criteria), or severe (6+ criteria). Approximately 14.5 million American adults have AUD, making it one of the most prevalent psychiatric conditions. The AUDIT (Alcohol Use Disorders Identification Test) screens across a spectrum from hazardous drinking to dependence; the CAGE questionnaire quickly screens for established alcohol problems. Alcohol withdrawal can be life-threatening (seizures, delirium tremens) and requires medical management. Evidence-based treatments include motivational interviewing, cognitive behavioral therapy, and medications (naltrexone, acamprosate, disulfiram). Early intervention during hazardous use can prevent progression to dependence.

The difference between oxygen in the alveoli (calculated) and oxygen in arterial blood (measured). A widened A-a gradient indicates a problem with oxygen transfer in the lungs, such as pulmonary embolism, pneumonia, or ARDS.

A caregiver/informant functional scale used to track daily living abilities in Alzheimer disease and related cognitive disorders.

The Amniotic Fluid Index (AFI) is an ultrasound-based measurement used to quantify amniotic fluid volume during pregnancy. The technique divides the uterus into four quadrants and measures the deepest pocket of amniotic fluid in each quadrant; these four measurements are summed to calculate the AFI. Normal AFI values range from 5-25 cm, with oligohydramnios (too little fluid) defined as AFI <5 cm, and polyhydramnios (too much fluid) defined as AFI >25 cm. Amniotic fluid serves critical functions including cushioning the fetus from trauma, allowing fetal movement and musculoskeletal development, maintaining temperature, facilitating lung development, and preventing umbilical cord compression. AFI is assessed during routine third-trimester ultrasounds and antepartum fetal surveillance. Alternative assessment methods include measuring the single deepest vertical pocket (normal 2-8 cm) or subjective assessment. Abnormal amniotic fluid volumes signal potential problems: oligohydramnios may indicate placental insufficiency, fetal growth restriction, ruptured membranes, or fetal genitourinary abnormalities, while polyhydramnios may suggest maternal diabetes, fetal anomalies (particularly gastrointestinal or neurologic), or twin-to-twin transfusion syndrome. Management depends on the underlying cause and severity, ranging from increased surveillance to delivery if fetal well-being is compromised.

Anhedonia is the diminished ability to experience pleasure or interest in activities that were previously enjoyable. It is one of two cardinal symptoms required for major depression diagnosis (along with depressed mood) and represents a core feature of melancholic depression. Anhedonia manifests as loss of interest in hobbies, social activities, food, sex, and other previously rewarding experiences. Patients often describe feeling 'emotionally flat' or unable to enjoy anything. The PHQ-9's first question specifically assesses anhedonia ('Little interest or pleasure in doing things'). Beyond depression, anhedonia occurs in schizophrenia, Parkinson's disease, substance use disorders during withdrawal, and as a negative symptom of chronic illness. Neurobiologically, anhedonia is linked to dysfunction in dopamine reward pathways, particularly the mesolimbic system. Treatment-resistant anhedonia is a clinical challenge; some antidepressants (bupropion, MAOIs) may be more effective than others for this symptom. Behavioral activation therapy specifically targets anhedonia by gradually reintroducing pleasurable activities.

The anion gap is a calculated value derived from standard electrolyte panels that represents the difference between measured cations (positively charged ions) and measured anions (negatively charged ions) in blood serum. The principle of electroneutrality requires that total positive and negative charges in blood be equal, but routine laboratory testing measures only some of these ions. The anion gap accounts for unmeasured anions including albumin, phosphate, sulfate, and organic acids. The calculation is typically anion gap = (Na+) − (Cl− + HCO3−), though potassium can be included as anion gap = (Na+ + K+) − (Cl− + HCO3−); potassium is often omitted given its minimal contribution to the gap. Normal anion gap ranges from 6 to 12 mEq/L (or 12-16 mEq/L if potassium is included), with most laboratories using 8-12 mEq/L as the reference range. The anion gap is primarily used to classify metabolic acidosis into two categories: high anion gap metabolic acidosis (HAGMA) and normal anion gap (non-anion gap) metabolic acidosis. In high anion gap metabolic acidosis, abnormal or excess acids accumulate in the blood—these unmeasured anions (lactate, ketones, toxic metabolites) increase the anion gap, typically to values exceeding 12-16 mEq/L. The classic mnemonic MUDPILES helps remember common causes of high anion gap metabolic acidosis: Methanol ingestion, Uremia (kidney failure with accumulated organic acids), Diabetic ketoacidosis (and alcoholic or starvation ketoacidosis), Propylene glycol, Isoniazid and Iron toxicity, Lactic acidosis (from tissue hypoperfusion, sepsis, seizures, or metformin), Ethylene glycol (antifreeze) ingestion, and Salicylate (aspirin) toxicity. Lactic acidosis and ketoacidosis are the most common causes in clinical practice. Normal anion gap metabolic acidosis (also called non-anion gap or hyperchloremic acidosis) occurs when bicarbonate is lost from the body or when the kidneys fail to excrete hydrogen ions, but this is accompanied by retention of chloride to maintain electroneutrality—thus the anion gap remains normal. Causes include diarrhea (gastrointestinal bicarbonate loss), renal tubular acidosis, carbonic anhydrase inhibitors like acetazolamide, early kidney disease, and rapid IV saline administration. The anion gap can be affected by changes in albumin concentration—since albumin is a major unmeasured anion, hypoalbuminemia decreases the anion gap by approximately 2.5 mEq/L for each 1 g/dL decrease in albumin below 4 g/dL. Therefore, in patients with low albumin, the anion gap should be corrected: corrected anion gap = measured anion gap + 2.5 × (4 − measured albumin). This correction is important because patients with hypoalbuminemia may have a high anion gap acidosis that appears normal on uncorrected calculations. Evaluation of an elevated anion gap should include measuring serum lactate, ketones (beta-hydroxybutyrate), creatinine, and consideration of toxic alcohol ingestion (methanol, ethylene glycol) with measurement of serum osmolality to calculate the osmolar gap.

A non-invasive vascular screening ratio calculated as ankle systolic pressure divided by brachial systolic pressure, commonly used to detect peripheral artery disease.

Ankylosing spondylitis is a chronic inflammatory arthritis primarily affecting the sacroiliac joints and spine, belonging to the family of spondyloarthropathies. It is strongly associated with the HLA-B27 antigen, present in 85-95% of patients with AS compared with 6-8% of the general population. AS predominantly affects young men (male-to-female ratio approximately 3:1), with typical onset between ages 20-40 years. The hallmark symptom is inflammatory back pain—insidious onset, age under 45, morning stiffness lasting more than 30 minutes, improvement with exercise (not rest), and nocturnal awakening. Progressive inflammation leads to new bone formation (syndesmophytes) and eventual spinal fusion, creating the classic "bamboo spine" appearance on X-ray. Extra-articular manifestations are common: acute anterior uveitis (25-40% of patients; recurrent, painful, photophobic eye inflammation), inflammatory bowel disease association (Crohn's disease, ulcerative colitis), psoriasis, and cardiac conduction abnormalities. The Assessment of SpondyloArthritis International Society (ASAS) criteria distinguish axial spondyloarthritis (with or without radiographic sacroiliitis) from peripheral spondyloarthritis. MRI of the sacroiliac joints detects active inflammation before X-ray changes appear, enabling earlier diagnosis of non-radiographic axial SpA. Inflammatory markers (CRP, ESR) are elevated in 50-70% of patients. Treatment: NSAIDs remain first-line and are highly effective—sustained NSAID use may retard radiographic progression. TNF inhibitors (adalimumab, etanercept, infliximab, certolizumab, golimumab) are the gold-standard biologic therapy, dramatically improving symptoms and functional outcomes. IL-17A inhibitors (secukinumab, ixekizumab) are effective alternatives, particularly for peripheral joint disease and psoriasis. Physical therapy and posture exercises are essential to maintain spinal mobility and prevent deformity. Disease monitoring uses the BASDAI (Bath AS Disease Activity Index) and ASDAS scores.

Antibiotic stewardship refers to coordinated programs and strategies to optimize antibiotic use in clinical practice—selecting the right antibiotic, at the right dose, for the right duration, targeting the right pathogen—with the goals of improving patient outcomes, reducing antibiotic-associated adverse effects, and curbing the development and spread of antibiotic resistance. Antimicrobial resistance (AMR) is one of the most significant public health threats globally, responsible for approximately 700,000 deaths annually worldwide (projected to exceed 10 million by 2050 if unaddressed). The overuse and misuse of antibiotics (including prescribing for viral infections, using broad-spectrum agents when narrow-spectrum would suffice, and unnecessarily long treatment durations) are the primary drivers of resistance emergence. Key stewardship strategies include: prospective audit and feedback (pharmacist or infectious disease specialist reviews antibiotic prescriptions and provides evidence-based recommendations); prior authorization (requiring approval for broad-spectrum or high-risk antibiotics before dispensing); clinical guidelines and order sets; culture-directed de-escalation (switching from empiric broad-spectrum therapy to targeted narrow-spectrum antibiotics when culture results return—'when in doubt, de-escalate'); duration optimization (clinical decision support for antibiotic duration based on infection type); diagnostic stewardship (improving test ordering and result interpretation to reduce inappropriate testing that leads to overtreatment); and dose optimization (pharmacokinetic/pharmacodynamic principles for aminoglycosides and vancomycin dosing). The Centor and McIsaac scores guide antibiotic prescribing for pharyngitis (avoiding antibiotics for viral causes), significantly reducing unnecessary prescribing. Sepsis protocols ensure timely antibiotic administration when needed, balancing the harm of delay against the harm of unnecessary treatment.

A medication-burden scoring approach that sums anticholinergic activity across a patient's drug list; higher totals indicate greater cognitive and functional adverse-effect risk.

Treatment with medications that prevent blood clots from forming or growing. Common anticoagulants include warfarin and direct oral anticoagulants (DOACs) like apixaban and rivaroxaban. Used to prevent stroke in AFib and treat/prevent blood clots.

Antinuclear antibodies are autoantibodies directed against components of the cell nucleus (DNA, histones, and various nuclear proteins). ANA testing by indirect immunofluorescence (IIF) on HEp-2 cells is the standard screening test for systemic autoimmune rheumatic diseases (SARDs). The ANA titer and pattern are reported together: the titer indicates the serum dilution at which the test remains positive (higher titers are more clinically significant); the pattern (homogeneous, speckled, nucleolar, centromere, etc.) provides clues to specific autoantibody types. An ANA titer of 1:40 or above is considered positive by most laboratories, though 1:80 or 1:160 is often used as a clinically meaningful threshold to reduce false positives. ANA positivity is present in over 99% of SLE patients (making it an excellent screening test), 95% of scleroderma, 70% of Sjogren's syndrome, 40% of primary biliary cholangitis, and 25-30% of rheumatoid arthritis. However, a positive ANA alone is not diagnostic of any disease—it occurs in 13-15% of healthy adults (particularly women and older individuals) and in many non-rheumatic conditions (viral infections, thyroid disease, malignancy). When the ANA is positive, specific extractable nuclear antigen (ENA) panel testing guides diagnosis: anti-dsDNA and anti-Smith are highly specific for SLE; anti-Ro/SSA and anti-La/SSB for Sjogren's and neonatal lupus; anti-Scl-70 (topoisomerase I) for diffuse systemic sclerosis; anti-centromere for limited systemic sclerosis (CREST); anti-Jo-1 for polymyositis/dermatomyositis with ILD; anti-U1RNP for mixed connective tissue disease. The clinical probability of SLE before testing significantly impacts the positive predictive value of ANA testing—in a low-risk patient with only fatigue and positive ANA 1:80, SLE is unlikely; in a patient with malar rash, arthritis, and nephritis, a positive ANA 1:320 is highly informative.

A quick assessment of newborn health performed at 1 and 5 minutes after birth. Evaluates Appearance (skin color), Pulse, Grimace (reflex irritability), Activity (muscle tone), and Respiration. Scores range from 0-10; scores below 7 may indicate need for medical attention.

A non-invasive liver fibrosis triage score calculated from AST, AST upper limit of normal, and platelet count: ((AST/ULN) x 100) / platelets.

The partial pressure of oxygen dissolved in arterial blood, measured by arterial blood gas (ABG). Normal is 80-100 mmHg at sea level. Directly measures oxygenation, unlike pulse oximetry which estimates it non-invasively.

Ascites is the pathological accumulation of fluid in the peritoneal cavity—the space between the two layers of the peritoneum that lines the abdominal organs. Cirrhosis of the liver is the most common cause of ascites, accounting for 80-90% of cases in developed countries. The development of ascites in cirrhotic patients marks the transition from compensated to decompensated cirrhosis and is associated with significantly reduced survival (approximately 50% two-year mortality without liver transplantation). The pathophysiology of cirrhotic ascites involves portal hypertension (increased pressure in the portal venous system due to scarred liver tissue obstructing blood flow), splanchnic vasodilation (widening of blood vessels in the intestinal circulation), activation of sodium-retaining hormones (renin-angiotensin-aldosterone system), and reduced albumin synthesis leading to decreased oncotic pressure. Other causes of ascites include heart failure (5-10% of cases), malignancy with peritoneal carcinomatosis (10%), tuberculosis, pancreatitis, and nephrotic syndrome. Symptoms of ascites include progressive abdominal distention and swelling, weight gain, shortness of breath (particularly when lying flat, as fluid compresses the diaphragm), early satiety, nausea, lower extremity edema, and reduced mobility. Physical examination may reveal bulging flanks, shifting dullness on percussion, and a fluid wave. Diagnosis is confirmed by abdominal ultrasound or CT scan. Diagnostic paracentesis (sampling ascitic fluid with a needle) should be performed in all new-onset ascites and whenever spontaneous bacterial peritonitis is suspected; fluid analysis includes cell count with differential, albumin (to calculate serum-ascites albumin gradient or SAAG), total protein, Gram stain, and culture. A SAAG ≥1.1 g/dL indicates portal hypertension as the cause, while SAAG <1.1 g/dL suggests other etiologies like malignancy or tuberculosis. Management of cirrhotic ascites follows a stepwise approach: the most important initial step is strict sodium restriction (limit to <2,000 mg daily), as excess sodium intake is the primary driver of fluid retention. For patients not responding to dietary sodium restriction alone, diuretic therapy is initiated with spironolactone (aldosterone antagonist) often combined with furosemide (loop diuretic), titrated to achieve gradual weight loss of 0.5 kg/day without peripheral edema or 1 kg/day with peripheral edema. Therapeutic large-volume paracentesis (removing 5+ liters) provides rapid symptomatic relief for tense ascites and can be repeated as needed. Refractory ascites (not responding to maximum medical therapy) may require serial large-volume paracentesis, indwelling peritoneal catheters, transjugular intrahepatic portosystemic shunt (TIPS), or liver transplantation evaluation.

The ratio of aspartate aminotransferase to alanine aminotransferase, used as an adjunct pattern marker in liver injury interpretation.