Normal Lithium Content in the Human Body
Lithium is present in trace amounts in the human body as a naturally occurring element obtained from dietary sources, though no specific quantitative reference range for total body lithium content in untreated individuals is established in clinical guidelines or FDA labeling.
Endogenous Lithium as a Trace Element
- Lithium exists naturally in the human body as a trace element that is ingested through food and drinking water 1
- The body contains lithium in physiological amounts that may have essential functions in mood regulation, though deficiency states have been associated with developmental defects in animals and psychopathological problems in humans 1
- Research suggests lithium may serve a physiological role in normal bodily function, though this remains incompletely understood 1
Therapeutic vs. Physiological Levels
The available evidence focuses primarily on therapeutic monitoring rather than baseline physiological content:
- Therapeutic serum concentrations for psychiatric treatment range from 0.6-1.2 mEq/L (or mmol/L), with maintenance levels typically 0.6-0.8 mEq/L 2, 3
- Serum levels above 1.5 mEq/L begin to pose toxicity risk, with serious toxicity occurring at >2.0 mEq/L 4, 5
- Brain lithium concentrations during treatment are approximately 50% of serum levels, occasionally reaching 75-80% 3
Important Clinical Context
- The distinction between trace physiological lithium and therapeutic dosing is substantial—therapeutic doses are dramatically higher than what occurs naturally 1
- Low-dose lithium supplementation (≤0.5 mM serum concentration) represents an intermediate range below standard psychiatric therapeutic levels but above typical dietary intake 6
- Lithium does not bind to plasma proteins and is almost exclusively excreted unchanged by the kidneys 3
Common Pitfall: Confusing naturally occurring trace amounts of lithium in the body with therapeutic serum levels used in psychiatric treatment—these represent entirely different magnitudes of exposure.