A clear, non-intimidating reference for common medical terms, abbreviations, and diagnostic phrases. Each definition is written in plain language to help you understand clinical reports, prepare for appointments, and communicate more confidently with your healthcare team.
Click a letter above to jump to that section. All definitions are reviewed for clinical accuracy and written for real people facing real health questions.
Anemia
A condition marked by a deficiency of red blood cells or hemoglobin, leading to reduced oxygen delivery to body tissues. Common symptoms include fatigue, weakness, pallor, and shortness of breath. Anemia can result from nutritional deficiencies, chronic disease, or blood loss, and is typically diagnosed through a complete blood count (CBC) panel.
Related Lab Test: Hemoglobin (Hb) and Hematocrit (Hct)
Blood Pressure (Systolic / Diastolic)
The force exerted by circulating blood against arterial walls. Systolic pressure (the top number) measures pressure during heartbeats when the heart pumps blood; diastolic pressure (the bottom number) measures pressure between beats when the heart rests. Normal adult blood pressure is typically below 120/80 mmHg. Persistent elevation above 130/80 mmHg may indicate hypertension and requires medical evaluation.
Related Lab Test: Blood Pressure Measurement (Sphygmomanometer)
Chronic Inflammation
A slow, long-term inflammatory response that can last for months or years, often playing a role in conditions like arthritis, cardiovascular disease, and autoimmune disorders. Chronic inflammation differs from acute inflammation (which is a normal immune response to injury) by persisting without resolution. Lifestyle factors, including diet, stress, and sleep quality, significantly influence inflammatory regulation.
Related Lab Test: C-Reactive Protein (CRP) and Erythrocyte Sedimentation Rate (ESR)
Dyspnea
The medical term for shortness of breath or difficulty breathing. Dyspnea can be acute (sudden onset) or chronic (persistent), and may be caused by respiratory conditions, cardiovascular issues, anemia, or anxiety. If you experience sudden, severe dyspnea with chest pain or confusion, seek emergency medical attention immediately.
Related Lab Test: Pulse Oximetry (SpO2) and Arterial Blood Gas (ABG)
Hypertension (High Blood Pressure)
A chronic condition in which the force of blood against arterial walls is consistently too high, typically defined as readings consistently above 130/80 mmHg. Untreated hypertension damages arterial walls over time, increasing the risk of heart attack, stroke, and kidney damage. Management includes lifestyle modifications (diet, exercise, stress reduction) and, when necessary, antihypertensive medications.
Related Lab Test: Blood Pressure Monitoring, Electrocardiogram (ECG)
Microbiome
The collective community of trillions of microorganisms—including bacteria, fungi, and viruses—that live on and inside the human body, particularly in the digestive tract. The microbiome plays a critical role in nutrient absorption, immune system regulation, and neurotransmitter production. Emerging research suggests that a balanced, diverse microbiome is associated with better metabolic health, mental wellbeing, and reduced systemic inflammation.
Related Lab Test: Stool Microbiome Analysis
Pallor
An abnormal paleness of the skin or mucous membranes, often indicating reduced blood flow or decreased red blood cell count. Pallor may be a visible sign of anemia, circulatory issues, or shock. If pallor is accompanied by dizziness, chest pain, or shortness of breath, prompt medical evaluation is recommended.
Related Lab Test: Complete Blood Count (CBC)
Placebo
A substance or treatment with no active therapeutic effect, often used as a control in clinical trials to evaluate the effectiveness of new medications or interventions. The placebo effect—a measurable improvement in symptoms experienced by patients who receive a placebo—demonstrates the powerful connection between belief, expectation, and physiological response.
Related Concept: Placebo Effect in Clinical Research
Prognosis
A medical prediction of the likely course and outcome of a disease or condition. Prognosis is typically based on statistical data from similar cases, taking into account the patient's age, overall health, and response to treatment. A "favorable prognosis" suggests a likely positive outcome, while a "guarded prognosis" indicates that the outlook is uncertain.
Related Concept: Clinical Outcomes & Prognostic Indicators
Spirometry
A common pulmonary function test that measures how much and how quickly a person can exhale air. Spirometry is used to diagnose and monitor respiratory conditions such as asthma, chronic obstructive pulmonary disease (COPD), and restrictive lung diseases. The test is non-invasive and typically takes 15–30 minutes to complete.
Related Lab Test: Forced Expiratory Volume (FEV1) and Forced Vital Capacity (FVC)
Triage
A process used in emergency settings to prioritize patients based on the severity of their condition. Triage ensures that individuals with life-threatening conditions receive immediate care, while those with less urgent concerns may be asked to wait. The system is designed to maximize efficient use of limited medical resources during high-demand situations.
Related Concept: Emergency Department Triage Protocols
Lipid Panel
A common blood test that measures total cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL), and triglycerides. Elevated LDL and triglyceride levels are associated with increased cardiovascular risk, while higher HDL levels are considered protective. Regular lipid panel monitoring is recommended for adults, especially those with a family history of heart disease.
Related Lab Test: Total Cholesterol, LDL, HDL, Triglycerides
HbA1c (Glycated Hemoglobin)
A blood test that measures the average blood sugar level over the past 2–3 months. HbA1c is used to diagnose and monitor diabetes and prediabetes. A normal HbA1c level is below 5.7%, while levels between 5.7% and 6.4% indicate prediabetes, and levels of 6.5% or higher indicate diabetes. Maintaining a healthy HbA1c is critical for preventing long-term complications.
Related Lab Test: Fasting Plasma Glucose (FPG)
TSH (Thyroid Stimulating Hormone)
A hormone produced by the pituitary gland that regulates thyroid function. Elevated TSH levels typically indicate an underactive thyroid (hypothyroidism), while low TSH levels suggest an overactive thyroid (hyperthyroidism). Thyroid hormones play a critical role in metabolism, energy regulation, and overall endocrine balance.
Related Lab Test: Free T3, Free T4, TSH
Complete Blood Count (CBC)
One of the most commonly ordered blood tests, providing a comprehensive overview of red blood cells, white blood cells, hemoglobin, hematocrit, and platelets. CBC results help clinicians diagnose and monitor anemia, infections, immune system disorders, and blood clotting abnormalities.
Related Components: RBC, WBC, Hb, Hct, Platelets