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Lithium in serum
Medical expert of the article
Last reviewed: 05.07.2025
The normal concentration of lithium in the blood serum is 0.14-1.4 μmol/l, when taking lithium preparations in therapeutic doses - 0.8-1.3 mmol/l. Toxic concentration is more than 2 mmol/l.
Lithium ions are absorbed in the gastrointestinal tract. It is excreted in urine (95%), feces (1%) and sweat (5%). The concentration of lithium in saliva is significantly higher than its concentration in blood serum. The blood-brain barrier is permeable to lithium, and its concentration in the cerebrospinal fluid is 40% of that in the blood serum. In the human body, the brain, kidneys, heart muscle and liver are the richest in lithium. Lithium specifically accumulates in thyrocytes and causes an increase in the thyroid gland in humans.
Determination of serum lithium concentration is important in lithium therapy and for the diagnosis of lithium poisoning.
No signs of lithium deficiency have been reported in humans.
Currently, lithium carbonate is used in psychiatric practice in doses up to 2.5 g/day (72 mmol), which increases the concentration of lithium in plasma to 0.5-1.5 mmol/l. It should be taken into account that in some cases, toxic phenomena may develop even at a concentration of 1.6 mmol/l. Lithium therapy is aimed at normalizing the exchange of mediators in the central nervous system. Lithium ions also affect some parts of the endocrine system, in particular the adrenal cortex, as well as the secretion of ADH. In psychiatric practice, the greatest effect is achieved in the prevention of affective disorders.
Rules for blood sampling for research. Venous blood serum is examined. During the monitoring process, lithium concentration is determined initially and before the next dose of the drug is administered.
There are known cases of occupational poisoning with lithium aerosols, which can cause tracheitis, bronchitis, interstitial pneumonia and diffuse pneumosclerosis. Contact of lithium preparations with skin and mucous membranes can cause burns. Symptoms of chronic lithium intoxication include general weakness, drowsiness, dizziness, loss of appetite, pain when swallowing, and tremor.
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