URINARY EXCRETION OF LITHIUM IN MANIA

Mood-dependent changes of serum lithium concentration in a rapid cycling patient maintained on stable doses of lithium carbonate

OBJECTIVE

Serum lithium levels may be influenced by mood state. We report on a 58-year-old female patient suffering from rapid cycling bipolar disorder. Her serum lithium levels varied greatly, despite stable medication.

METHODS

The patient was observed over a one-year period.

RESULTS

The patient received a stable medication of lithium carbonate (450 mg), valproate (1500 mg), and clozapine (200 mg). Investigating mood and serum lithium levels over one year revealed six manic and six depressive phases. The mean lithium serum level was 0.67 mmol/L in the depressive states, 0.39 mmol/L in the manic states (t = 4.11, p = 0.001 versus depression), and 0.40 mmol/L in the euthymic states (t = 3.58, p = 0.003 versus depression). Noncompliance was ruled out. The patient gained up to 8 kg during manic phases, accompanied by pretibial edema.

CONCLUSIONS

Changes in serum lithium concentration are probably not caused by altered lithium, but by water metabolism. During mania, body water increases, leading to dilution and therefore a reduction in serum lithium levels. As there is no proof for any other known cause of hypervolemia, we propose the hypothesis that the increase in body water is due to a variant of idiopathic edema.

The use of sodium and potassium to reduce toxicity and toxic side effects from lithium

Studies in rats find that the animals develop toxic side effects at serum levels which are therapeutic for man. Most of the toxic effects were prevented by feeding sodium and potassium. The rats must ingest and excrete comparatively higher amounts of lithium than humans to maintain these levels. Sodium used alone has been shown to reduce side effects in man, but was found to reduce therapeutic effectiveness at fixed lithium dosages. Evidence is presented to suggest that therapeutic effectiveness can be maintained and toxic side effects and risk of toxicity reduced, by using both sodium and potassium, and by modestly raising the dosage of lithium.

The influence of mania and depression on the pharmacokinetics of lithium. A longitudinal single-case study

A 28-year-old woman, had, every month, a premenstrual manic-depressive cycle beginning with a hypomanic episode followed by a depression which improved with menstruation. The lithium serum level oscillated in a regular and inverse relationship to the mood changes, although the patient received a constant dosage of lithium: 16.2 mmol/l per day. The lithium level reached its highest value at the time of the greatest intensity of depression (1.10 mmol/l), and its lowest value during the time of hypomania (0.30 mmol/l), whereas it showed only small oscillations around 0.5 mmol/l when the patient's mood was normal. RBC lithium concentration and lithium excretion in the urine followed the same pattern. The daily creatinine excretion was usually within normal limits. It must be hypothesized that there are compartments or stores, to and from which lithium is transported, by mechanisms related to the biological basis of mood changes.

The effects of administering lithium carbonate on the balance of Na, K and water in manic-depressive patients

Eleven patients in remission from manic-depressive illness were studied by means of metabolic balances before and after the administration of lithium carbonate. Lithium caused a sharp diuresis of isotonic saline and a smaller excretion of potassium over the course of two days. During the subsequent two days there occurred a compensatory retention of Na, K and water. These short-term changes were not associated with any significant alteration in the patients' mood. There was no significant and systematic retention of Na, K or water over the 14 days of Li administration. The recovery of Li was measured simultaneously. During the first week only a proportion of the administered Li was recovered in the urine and faeces, suggesting that a gradual distribution of Li throughout its body space was occurring. After the first week, nearly all the administered Li was recovered, indicating an equilibrium with an even distribution of the ion throughout its body space. This equilibrium was more complete at this early stage in those patients who had been given a smaller dose of lithium carbonate.

Lithium carbonate

The pertinent literature on lithium has been reviewed. It appears that in recent years there is renewed interest in the drug, its general and specific usage, its toxic effects and its research. It seems to have been generally accepted as specifically effective in the treatment of acute manic psychosis, and also it is believed to be useful as a prophylactic agent in selected cases of recurrent affective disorders.

Cerebrospinal fluid lithium in manic illness

The lithium ion has been found increasingly valuable in the treatment of manic illness (1, 2). In the therapeutic use of lithium there are two phases, stabilization and maintenance. These data have been reviewed by Gershon and Yuwiler (1), but a clear explanation of the pharmacodynamics involved is not evident. Animal experimentation has been used to study the behaviour of the lithium ion as compared with other cations. The lithium ion's behaviour resembles sodium in some tissues and enzyme systems but is more like potassium in others. These authors have reported a three- to fourfold increase in the tolerance for toxic symptoms due to lithium ion in manic patients as compared to normals. They found that this increased tolerance decreased to normal as the patient's manic state subsided.