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Peptide glossary

116 terms you meet on vendor pages, lab reports and research papers, defined in plain language with a source for each. For worked examples see Peptide basics; for the math, the calculators.

Foundations (33)Measurements (50)Nutrition (11)Units & records (22)

Foundations

Absorption: Movement of a substance from its administration site into the circulation. Source: cancer.gov
Adverse event: An unwanted medical occurrence; a temporal association alone does not prove its cause. Source: cancer.gov
Agonist: A substance that activates a receptor. Source: cancer.gov
Amino acid: A building block used to make peptides and proteins. Source: cancer.gov
Antagonist: A substance that blocks activation of a receptor. Source: cancer.gov
Bioavailability: The fraction of an administered amount that reaches the systemic circulation unchanged. Source: cancer.gov
Blinding: Keeping group assignments unknown to participants or researchers to reduce bias. Source: cancer.gov
Causation: A relationship in which one factor produces a change in another. Source: cancer.gov
Clinical trial: A research study involving people to evaluate a health-related intervention. Source: cancer.gov
Concentration: An amount of a substance per unit volume. Source: cancer.gov
Contraindication: A circumstance in which a treatment should not be used because of its risk. Source: cancer.gov
Correlation: A statistical relationship between variables that does not by itself prove causation. Source: cancer.gov
Distribution: Movement of a substance from the circulation into tissues. Source: cancer.gov
Elimination: Removal of a substance through metabolism or excretion. Source: cancer.gov
Enzyme: A biological catalyst that helps a chemical reaction occur. Source: cancer.gov
Excretion: Removal of substances from the body, for example through urine. Source: cancer.gov
Half-life: The time for an amount or concentration to decrease by half under specified conditions. Source: cancer.gov
Hormone: A chemical messenger that carries signals between cells or organs. Source: cancer.gov
Interaction: A change in a substance’s effects caused by another substance or exposure. Source: cancer.gov
Metabolism: The chemical processes that sustain the body, including processing nutrients and medicines. Source: cancer.gov
Observational study: Research that measures exposures and outcomes without assigning the exposure being studied. Source: cancer.gov
Off-label use: Use of an approved medicine outside the conditions specified in its approved labeling. Source: cancer.gov
Peak: The highest value in a specified measurement period. Source: cancer.gov
Peptide: A chain of amino acids linked together. Source: cancer.gov
Pharmacodynamics: The study of a substance’s effects on the body. Source: cancer.gov
Pharmacokinetics: The study of how a substance is absorbed, distributed, metabolized and eliminated. Source: cancer.gov
Placebo: An inactive comparison used in some clinical studies. Source: cancer.gov
Protein: A molecule made from amino-acid chains folded into a functional shape. Source: cancer.gov
Randomization: Assigning study participants to groups by chance. Source: cancer.gov
Receptor: A cell structure that recognizes a particular signal or molecule. Source: cancer.gov
Steady state: A condition in which repeated input and removal produce a repeating concentration pattern. Source: cancer.gov
Tolerance: A reduced response to a substance after repeated exposure. Source: cancer.gov
Trough: The lowest value in a specified measurement period. Source: cancer.gov

Measurements

Albumin: A protein made by the liver that helps carry substances and maintain fluid balance. Source: medlineplus.gov
ALP: Alkaline phosphatase: an enzyme associated with tissues including the liver and bones. Source: medlineplus.gov
ALT: Alanine aminotransferase: an enzyme measured in blood tests commonly used to assess liver health. Source: medlineplus.gov
AST: Aspartate aminotransferase: an enzyme found in the liver, muscles and other tissues. Source: medlineplus.gov
Baseline: A starting measurement used for comparison with later results. Source: medlineplus.gov
Bilirubin: A substance formed during the breakdown of red blood cells and processed by the liver. Source: medlineplus.gov
Bioimpedance (BIA): A method that estimates body composition using electrical properties and a prediction model. Source: medlineplus.gov
Biomarker: A measurable characteristic used to describe a biological process or response. Source: medlineplus.gov
Body fat percentage: The proportion of body mass estimated to be fat. Source: medlineplus.gov
BUN: Blood urea nitrogen: a measure of nitrogen in a waste product carried in blood. Source: medlineplus.gov
C-peptide: A substance released when the body produces insulin; it can help assess insulin production. Source: medlineplus.gov
Calcium: A mineral used in bones, muscle function and cell signaling. Source: medlineplus.gov
CBC: Complete blood count: a group of measurements of blood cells and related characteristics. Source: medlineplus.gov
Cholesterol: A lipid used in cell membranes and other body functions. Source: medlineplus.gov
Cortisol: An adrenal hormone involved in metabolism and stress responses; levels vary with timing and context. Source: medlineplus.gov
Creatinine: A waste product related to muscle activity that is used in assessments of kidney filtration. Source: medlineplus.gov
CRP: C-reactive protein: a blood marker that can rise with inflammation and does not identify its cause by itself. Source: medlineplus.gov
DEXA (DXA): Dual-energy X-ray absorptiometry: an imaging method used for bone density and some body-composition measurements. Source: medlineplus.gov
Diastolic pressure: Blood pressure between heartbeats. Source: medlineplus.gov
eGFR: Estimated glomerular filtration rate: a calculated estimate of kidney filtration. Source: medlineplus.gov
Estradiol: A form of estrogen involved in reproductive and other body functions. Source: medlineplus.gov
Fasting sample: A sample collected after following specified instructions about avoiding food or drink. Source: medlineplus.gov
Ferritin: An iron-storage protein; a blood ferritin test helps assess iron stores in context. Source: medlineplus.gov
Free T3: Triiodothyronine that is not bound to blood proteins. Source: medlineplus.gov
Free T4: Thyroxine that is not bound to blood proteins. Source: medlineplus.gov
GGT: Gamma-glutamyl transferase: an enzyme measured in assessments involving the liver and bile ducts. Source: medlineplus.gov
Glucose: A sugar used by cells for energy; a glucose test measures its amount in a sample. Source: medlineplus.gov
HbA1c (A1C): A measure of glucose attached to hemoglobin that reflects average blood glucose over roughly the past three months. Source: medlineplus.gov
HDL cholesterol: Cholesterol carried by high-density lipoproteins. Source: medlineplus.gov
Hematocrit: The proportion of blood volume occupied by red blood cells. Source: medlineplus.gov
Hemoglobin: The oxygen-carrying protein inside red blood cells. Source: medlineplus.gov
HRV: Heart rate variability: variation in the timing between heartbeats. Source: medlineplus.gov
IGF-1: Insulin-like growth factor 1: a protein involved in growth signaling. Source: medlineplus.gov
Insulin: A hormone that helps regulate blood glucose and nutrient storage. Source: medlineplus.gov
LDL cholesterol: Cholesterol carried by low-density lipoproteins. Source: medlineplus.gov
Lean body mass: Body mass excluding fat; it includes more than skeletal muscle alone. Source: medlineplus.gov
Platelets: Blood components that help form clots. Source: medlineplus.gov
Potassium: An electrolyte needed for normal nerve, muscle and heart function. Source: medlineplus.gov
Reference range: The comparison interval supplied by a laboratory for a particular test and population. Source: medlineplus.gov
Resting heart rate: The number of heartbeats per minute measured while at rest. Source: medlineplus.gov
RMSSD: A heart rate variability statistic based on successive differences between normal heartbeat intervals. Source: medlineplus.gov
SDNN: A heart rate variability statistic based on the standard deviation of normal heartbeat intervals. Source: medlineplus.gov
Sodium: An electrolyte involved in fluid balance and nerve and muscle function. Source: medlineplus.gov
Systolic pressure: Blood pressure during the heart’s contraction. Source: medlineplus.gov
Testosterone: A hormone involved in reproductive function and other body processes. Source: medlineplus.gov
Trend: A pattern across measurements over time. Source: medlineplus.gov
Triglycerides: A form of fat measured in blood and stored for energy. Source: medlineplus.gov
TSH: Thyroid-stimulating hormone: a pituitary signal that helps regulate thyroid hormone production. Source: medlineplus.gov
Vitamin D: A nutrient and hormone precursor involved in calcium regulation and bone health. Source: medlineplus.gov
White blood cells: Blood cells involved in immune defenses. Source: medlineplus.gov

Nutrition

Carbohydrate: A nutrient category that includes sugars, starches and fiber. Source: medlineplus.gov
Dietary fat: A nutrient that provides energy and supports functions such as absorption of fat-soluble vitamins. Source: medlineplus.gov
Dietary fiber: Carbohydrate components that resist digestion in the small intestine. Source: medlineplus.gov
Dietary protein: A nutrient that supplies amino acids. Source: medlineplus.gov
Electrolyte: A mineral carrying an electrical charge when dissolved in body fluids. Source: medlineplus.gov
Hydration: The body’s water status; a logged water total alone does not measure it. Source: medlineplus.gov
Kilocalorie (kcal): A unit of energy; food labels often call a kilocalorie a Calorie. Source: medlineplus.gov
Macronutrient: A nutrient used in relatively large amounts, such as protein, carbohydrate or fat. Source: medlineplus.gov
Micronutrient: A vitamin or mineral needed in smaller amounts. Source: medlineplus.gov
Portion: The amount of food a person actually eats. Source: medlineplus.gov
Serving size: The amount of food to which a nutrition label’s listed values apply. Source: medlineplus.gov

Units & records

Adherence: How recorded behavior compares with an agreed plan; Plan Your Peptides counts scheduled entries marked taken.
Backfill: Recording an event for an earlier date while preserving when it actually happened.
Backup: A saved copy that can be restored later; saving a backup does not continuously synchronize devices.
Beyond-use date: A date after which a prepared product should not be used; it may differ from the original expiration date.
Conflict: Different edits to the same record that require reconciliation.
Diluent: A liquid used to dissolve or dilute a substance.
Duplicate: A second record of the same event, which can incorrectly inflate totals.
Expiration date: The manufacturer’s labeled limit for a product under its specified storage conditions.
International unit (IU): A substance-specific unit of biological activity; it has no universal conversion to milligrams.
Lot number: A manufacturer’s identifier for a production batch.
mg/dL: Milligrams per deciliter: a mass concentration often used in lab reports.
mg/mL: Milligrams per milliliter: a mass concentration.
Microgram (mcg, µg): One millionth of a gram; 1,000 mcg equals 1 mg.
Milligram (mg): One thousandth of a gram; 1 mg equals 1,000 micrograms.
Milliliter (mL): One thousandth of a liter; a unit of volume, not mass.
mmol/L: Millimoles per liter: a concentration based on the amount of a particular chemical substance.
Modeled mass: An illustrative amount remaining from recorded mass-based entries under an entered half-life assumption, not a measured blood concentration.
Profile: A separate set of personal records in Plan Your Peptides.
Reconstitution: Adding a specified diluent to a product; follow the product’s instructions and prescribed plan.
Snapshot: A saved view at a particular time; a widget snapshot may become outdated.
Symptom follow-up: A dated record of an action, observed outcome and optional severity after symptom onset.
Sync: Exchanging changes between devices or a service, including handling conflicts.