GLOSSARY

Deiodinase Type 1 (DIO1) is a deiodinase type contributing to thyroid-hormone turnover and conversion.

The thyroid axis uses hypothalamic and pituitary signals with hormonal feedback. Total hormone, free fraction and peripheral conversion are different measurements. Deiodinases support activation or inactivation; reverse T3 is not active T3. Illness, medicines and energy insufficiency can affect results. Sluggishness or a single result does not establish hypothyroidism, and thyroid hormone is not a tool for self-directed athletic weight manipulation; interpretation requires the full clinical and laboratory pattern.

Hormonal axes use feedback and often pulsatile and time-dependent patterns. A rise can be compensatory and a decline temporarily adaptive, neither diagnosing disease without context. Hormone ratios depend on numerator, denominator, timing and units. Sports nutrition does not aim to maximize every hormone; the practical goal is adequate supply and appropriate physiological responses, evaluated with health and performance rather than an isolated ratio or peak.

Synthesis, storage, secretion, transport and clearance are distinct processes. Blood concentration reflects entry and removal rather than directly measuring secretion; exercise-related plasma-volume changes can also affect it. Half-life depends on hormone form and method and is not identical to the duration of all effects. Comparisons therefore need sampling time, previous food and recent activity standardized or recorded rather than interpreting isolated concentration differences without context.

For practical use, record meal and training timing, sleep and hunger alongside actual intake and performance trends. When a marker changes, first examine measurement conditions and plausible explanations; food decisions should support adequate supply, tolerance and recovery rather than ending the assessment at one molecular signal or assuming a concentration change automatically establishes a useful intervention.

Low energy availability means insufficient energy remains after exercise for required bodily functions; it is not synonymous with low carbohydrate or weight loss alone. Problematic exposure can affect reproductive, thyroid, bone and appetite systems with variable patterns. Restoring supply and reviewing training load are central to assessment. One normal hormone or a universal numerical cutoff cannot confirm or exclude every case, so symptoms, history and clinical evaluation must be integrated.

Sensitivity is response to a given signal and is not identical to hormone concentration or receptor number. Receptor abundance, binding and downstream signaling can each alter response. Maximum responsiveness also differs from a shift in sensitivity. One blood value cannot describe all tissue receptors; assay type and target tissue are needed to interpret resistance or sensitivity rather than treating these as directly interchangeable concentration measurements.

Hormonal imbalance is a broad description rather than a standalone diagnosis from an online symptom list. Deficiency, excess and resistance differ, and reference ranges depend on method, age and conditions. Medicines, illness, sleep and energy status also matter. Persistent symptoms need appropriate assessment to identify causes; choosing supplements or manipulating hormones from one isolated test cannot replace evidence-based evaluation or establish a universal athletic hormone target.