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Interpretive Handbook

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Test 8384 :
Lithium, Serum

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Lithium alters the intraneuronal metabolism of catecholamines by an unknown mechanism. It is used to suppress the manic phase of manic-depressive psychosis.

 

Lithium is distributed throughout the total water spaces of the body and is excreted primarily by the kidney.

 

Toxicity from lithium salts leads to ataxia, slurred speech, and confusion. Since the concentration of lithium in the serum varies with the time after the dose, blood for lithium determination should be drawn at a standard time, preferably 8 to 12 hours after the last dose (trough values).

Useful For Suggests clinical disorders or settings where the test may be helpful

Monitoring therapy of patients with bipolar disorders, including recurrent episodes of mania and depression

 

Evaluating toxicity

Interpretation Provides information to assist in interpretation of the test results

Therapeutic concentration: 0.8 to 1.2 mmol/L (trough concentration)

 

Toxic concentration: >1.6 mmol/L

 

There is no relationship between peak concentration and degree of intoxication.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

No significant cautionary statements

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

Therapeutic concentration: 0.8-1.2 mmol/L (trough concentration)

Toxic concentration: >1.6 mmol/L

There is no relationship between peak concentration and degree of intoxication.

Clinical References Provides recommendations for further in-depth reading of a clinical nature

1. Judd LL: The therapeutic use of psychotropic medications: lithium and other mood-normalizing medications. In Harrison's Principles of Internal Medicine. Twelfth edition. Edited by JD Wilson, E Braunwald, KJ Isselbacher, et al. New York, McGraw-Hill Book Company, 1991, pp 2141-2143

2. Gelenberg AJ, Kane JM, Kekller MB, et al: Comparison of standard and low serum levels of lithium for maintenance treatment of bipolar disorder. N Engl J Med 1989;321:1489-93

3. Lithium Product Monograph, Physicians’ Desk Reference (PDR). Sixty-first edition. Montvale, NJ: Thomson PDR, 2007


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