Wednesday, April 28, 2010

Lithium Carbonate

Lithium Carbonate is a mainstay medication in psychiatry. It's been tried and proven in the treatment of Bipolar Disease.
Historically there was only one bipolar disease, that which was called Manic Depressive disorder. This was a horrible disease with Mania so severe that it could last untreated and lead to death from hyperactivity, grandiose delusional thinking and angry outbursts. Later the cyclothymic disturbance of mood swings, a very attenuated form of the classic illness was called Bipolar II.

Lithium Carbonate was and probably still is the drug of choice for Bipolar I especially the Manic episode. It's also an amazing 'preventative medication'.

The story goes that Lithium Carbonate's special capacity for modulating mood was found when it was used for heart patients as Lithium Salt instead of normal table salt, Sodium Salt. People were noted to be 'mellow' and from this 'observational' history the medication use developed.

Lithium Carbonate's pharmacological 'raison d'etre' isn't clearly known. It's thought that somehow it stabilizes membranes. Empirically it works and it works very well.

It's also relatively safe at low dosage used most commonly in the community. With increasing dosage there is increasing toxicity.

When LithiumCarbonate is started it's standard to check the blood work. Lithium can be toxic to the thyroid gland so TSH (Thyroid Stimulating Hormone) is ordered to measure baseline activity in case there is any change while on Lithium. The other organ which can be involved are the Kidneys so Creatinine is measured along with the Glomerular Filtration Rate, tests that assess the filtering function. If the Creatinine were to increase it would indicate that the filtering function of the kidneys were impaired. Sometimes an Electrocardiogram is taken if there is any concern about heart function as Lithium can cause arrythmias. Once a person is established on the best Lithium dosage for the individual these tests are repeated initially at 3 -6 months and then annually while the person is on Lithium.

Lithium is usually begun in the 300 mg three times a day dosage. The blood level of Lithium is then measured since each person's metabolism is different. Acceptable blood levels for Lithium treatment of bipolar disorder are in the range of .6 to 1.2 mEq/litre. By adding or subtracting 300 mg of Lithium roughly in the range 600 to 1500 mg a day, the desired lithium level is achieved. Lithium equilibriates such that drug test for Lithium level can be done 1-2 weeks after altering the dosage. The idea is to have the level at the lower end when a person is relatively stable and at the higher end when a person is more manic. In hospital for mania acute treatment it's not uncommon to aim for a lithium level just short of toxicity in the 1.5 mEq/litre range.

Once stable Lithium levels, Na. K. CBC Cr and TSH and urinalysis are done with decreasing frequency to annually in a person stable on Lithium.

Because dehydration can affect the lithium level, when people are sick with fever or diarrhea it's good to check the lithium level. Lithium toxicity is usually noted subjectively first as an increasing tremor or trembling.

There is a common expression in clinical medicine that goes, treat the person, not the lab. This refers to the fact that many people individually benefit from medication dosage that doesn't quite go with what the textbooks would say. This is often true with Lithium Carbonate where maintenance dosages do not necessarily have to be strictly in the 'drug level' range as patients may remain stable on a lower dosage with the potential for a greater safety. The key here is that if a person is already on Lithium and develops mania and or depression the optimum dosage can be reached more easily than if a person were started from scratch or with no lithium on board. To this end I was interested to note that Lithium Carbonate was used as an adjunctive medication in the Star D Protocols for chronic depressions clearly indicating the potency of the medication as an adjunctive. Many patients benefit from 300 to 600 mg a day as prevention and for stabilization in maintenance. For treatment however this not adequate and the standard textbooks mirror clinical practice where often much higher dosages are needed to stabilize the Bipolar Disorder.

Sleep disorder increasingly is seen to be part of the Bipolar Disorder with insomnia associated with mania and hypersomnia associated with some depressions of the Bipolar class.

Lithium Carbonate may well affect the sleep cycle and thereby help with the mood disorder. It's commonly used with antidepressants especially SSRI's when a person is in the depressed phase and it's safely used with other mood stabilizers when a person is having manic symptons.

That said, it's an amazing medication that has allowed many people to live essentially normal lives with excellent long term work and stable intimate and conventional relationships. Without lithium these very same people might well have spent inordinate time in hospital and certainly would have not had the same success in the community. Fortunately too there are new medications which combine with Lithium to provide even better finer tuned care for patients with Bipolar disorder.

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