Lithium

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Lithium

Lithium—which has the highest specific heat of any solid element—is the first element in Group 1 of the periodic table, a group of elements generally known as the alkali metals. It is the lightest of all metals. Lithium’s atomic number is 3, its atomic mass is 6.941, and its chemical symbol is Li.

Properties

Properties Lithium is a very soft, silvery metal with a melting point of about 356.97°F (180.54°C), a boiling point of 2,435°F (1,335°C), and a density of 0.308 ounces per cubic inch (0.534 grams per cubic centimeter). It is a solid at room temperature. Lithium is extraordinarily soft for a metal with a rating of 0.6 on the Mohs scale, softer even than talc, whose Mohs rating is 1.

Lithium is an active metal, although, as one would predict from its placement in the periodic table, is not as active as sodium, potassium, and the other alkali metals. For example, it reacts slowly with cold water, releasing hydrogen gas. It does not react with oxygen at room temperature, although it does react at higher temperatures to form lithium oxide (LiO₂). Under the proper conditions, the element also reacts with sulfur, hydrogen, nitrogen, and the halogens.

Lithium is about the 15th most abundance element in the Earth’s crust with an abundance of about 0.005%. Its estimated crustal abundance is 3.2 x 10^-4 ounces per pound (2.0 x 10¹ milligrams per kilogram) and its estimated oceanic abundance is 2.4 x 10^-5 ounces per gallon (1.8x10^-1 milligrams per liter. Lithium never occurs as a free element, but it is found in minerals such as spodumene, petalite, and lepidolite. Some lithium is also found in seawater, primarily as dissolved lithium chloride (LiCl). The world’s largest producer of lithium is the United States, followed by the countries of Australia, Russia, Canada, Zimbabwe, Chile, and China. In the United States, lithium is produced at three large mines in Nevada and North Carolina.

The first step in extracting lithium from its ores is to convert the ore to lithium chloride, which is then electrolyzed to obtain the pure element: 2LiCl— electric current←→ 2Li + Cl₂.

History

The use of lithium for medicinal purposes can be traced back over 1,800 years to Greek physician Galen, who treated patients with mania by having them bathe in alkaline springs and drink the water,which probably contained lithium. In 1817, Swedish chemist August Arfwedson (or Arfvedson; 1792–1841), described the element lithium, which he named from the Greek word that means stone. Arfwedson was not able to prepare pure lithium because it was too active. That step was accomplished about a year later by the Swedish chemist William Thomas Brande (1788–1866) and the English chemist Sir Humphry Davy (1778–1829), both of whom used a method similar to the one employed today for extracting lithium from lithium chloride by electrolysis.

In the 1840s, lithium was mixed with carbonate or citrate to form a salt and was used to treat gout, epilepsy, diabetes, cancer, and sleeplessness. None of these treatments were effective, but interest in lithium as a medicine continued. In the 1940s, lithium chloride was administered as a salt substitute for patients requiring low-salt diets. This proved to be dangerous because an insufficient amount of sodium in the body causes lithium to build up. Too much lithium can cause poisoning and even death if the levels become too high.

Treatment

Lithium has been the treatment of choice for bipolar disorder (formerly called manic-depressive illness) for several decades. Lithium is a trace element found in plants, mineral rocks, and in the human body. Today, the major source of medical lithium is mines in North Carolina. Lithium is classified as an antimonic medication because of its ability to reverse mania, a mood disorder characterized by extreme excitement and activity. In addition, lithium is also effective in reversing deep depression, the other mood extreme of bipolar disorder, and in decreasing the frequency of manic and depressive cycles in patients.

While there has been a great deal of success in treating bipolar patients with lithium and returning them to a normal life, researchers are not exactly sure how it works. It is a non-addictive and non-sedating medication, but its use must be carefully monitored for possibly dangerous side effects. For some patients suffering from some symptoms of schizophrenia, lithium may be used in combination with other medications. Lithium is also used to treat people who suffer from unipolar depression.

Before lithium was in general use for the treatment of bipolar disorder, as many as one in five patients with this condition committed suicide. Many who suffered from this illness were never able to live normal, productive lives. Lithium therapy now allows many people with bipolar disorder to participate in ordinary everyday life. Seventy to 80% of bipolar patients respond well to lithium treatment without any serious side effects.

John Cade

The story of lithium parallels other stories in medical history where the medicinal value of a substance is discovered accidentally. In 1949, John Cade, an Australian psychiatrist, decided to experiment with lithium on guinea pigs. He theorized that uric acid was a cause of manic behavior. Since he needed to keep the uric acid soluble, he used lithium salts as an agent in the solution. The guinea pigs did not become manic as he expected, but instead they responded by becoming extremely calm.

When Cade used the lithium treatment on 10 manic patients, he reported remarkable improvement in the patients’ condition. One patient who had been in a manic state for five years was able to leave the hospital after a three-month treatment and resume a normal life. Cade reported his results in the Medical Journal of Australia, but his findings did not have an impact on the medical community at that time.

When Cade carried out his experiments, reports of lithium poisonings were widespread in the United States. It was not until the work of Mogens Schou, who campaigned for recognition of lithium as a treatment for bipolar disorfder, that acceptance of lithium began. In the United States, however, it did not gain full FDA (Federal Drug Administration) approval until 1974, although trials were conducted during the 1960s.

Administration

The dosage of lithium must be regulated on an individual basis. The level of concentration in the blood must be approximately between 0.8 to 1.4 milli-equivalents per liter of blood. For this reason, blood samples must be taken regularly when a person is receiving lithium treatment. When the concentration of lithium is too low, the desired results will not be obtained and if it is too high, there may be adverse side effects.

Initially, the dose given is very low, then a blood sample is taken, and the dosage is increased gradually until the desired concentration is reached. When therapy is initiated, blood samples are taken every three or four days, then once a week, progressing to every two weeks, once a month, then perhaps every three or four months. In order to maintain the desired level, the medication is usually taken periodically throughout the day, depending upon the dosage. Slow-release and sustained-release tablets and capsules have been developed that make the administration of lithium medication easier. It is sometimes taken in liquid form as well.

KEY TERMS

Bipolar disorder —Manic-depressive illness, a condition where the patient exhibits both an excited state called mania and a depressed state.

Electroconvulsive therapy (ECT)

—Administration of a low dose electric current to the head in conjunction with muscle relaxants to produce convulsions. A treatment method whose underlying action is still not fully understood, it has proven effective in relieving symptoms of some severe psychiatric disorders for which no other treatment has been effective, for example, severe depression.

Schizophrenia —A mental illness characterized by thought disorder, distancing from reality, and sometimes delusions and hallucinations.

Unipolar depression —A mental illness in which the patient suffers from depression only.

Precautions

Lithium is absorbed quickly into the bloodstream and carried to all tissues of the body and brain. It is excreted through the kidneys. Because sodium is also passed out through the kidneys and affects lithium secretion, a normal sodium balance is necessary to maintain a lithium balance as well. If there is an insufficient amount of sodium in the body, the lithium builds up and can become toxic.

Besides avoiding a low-salt diet, patients receiving lithium therapy for bipolar disorder are cautioned to drink alcohol in moderation and to discuss all over-the-counter and prescription medicine with their psychiatrists, since some antibiotics and anti-inflammatory agents like ibuprofen can increase lithium levels in the bloodstream. The use of lithium during pregnancy presents certain risks. Electroconvulsive therapy (ECT) is sometimes recommended for pregnant patients who have been taking lithium as treatment for bipolar disorder. Older persons on lithium and low-salt diets must also be cautious.

Possible side effects of lithium therapy are stomach ache, nausea, vomiting, diarrhea, hand tremors, thirst, fatigue, and muscle weakness. Some patients report weight gain while on lithium and a thyroid condition may develop, but can be easily treated with thyroid replacement hormones.

By and large, lithium treatment has been an effective drug for patients suffering from bipolar disorder. Many remain in treatment for extended periods of time without any harmful side effects, and most importantly, are able to lead normal and productive lives without hospitalization.

Resources

BOOKS

Akiskal, Hagop S., and Mauricio Tohen, eds. Bipolar Psychopharmacotherapy: Caring for the Patient. Chichester, UK, and Hoboken, NJ: John Wiley & Sons, 2006.

Bauer, Michael, Paul Grof, Bruno Muller-Oerlinghausen, eds. Lithium in Neuropsychiatry: The Comprehensive Guide. Abingdon, UK: Informa Healthcare, 2006.

Emsley, John. Nature’s Building Blocks: An A-Z Guide to the Elements. Oxford, UK: Oxford University Press, 2003.

Schou, Mogens. Lithium Treatment of Mood Disorders:A Practical Guide. Basel, Switzerland, and New York: Karger, 2004.

Siekierski, Slawomir. Concise Chemistry of the Elements. Chichester, UK: Horwood Publishing, 2002.

Yatham, Lakshmi N., Vivek Kusurnakar, Stanley P. Kutcher, eds. Bipolar Disorder: A Clinician’s Guide to Biological Treatments. New York: Brunner-Routledge, 2002.