Clinical Significance

Lithium is widely used in the treatment of manic-depressive psychosis. Administered as lithium carbonate, it is completely absorbed by the gastro‑intestinal tract; peak serum levels occur 2 to 4 hours after an oral dose. The half-life in serum is 48 to 72 hours and it is cleared through the kidneys (excretion parallels that of sodium). Reduced renal function can prolong clearance time. Lithium acts by enhancing the uptake of neurotransmitters, which produces a sedative effect on the central nervous system. Serum lithium concentrations are measured essentially to ensure compliance and to avoid toxicity. Early symptoms of intoxication include apathy, sluggishness, drowsiness, lethargy, speech difficulties, irregular tremors, myoclonic twitching’s, muscle weakness and ataxia. 

_{Source: Roche Cobas LI Method Sheet Version 2.0 2022-01}