Pre-treatment evaluation for Lithium therapy - Serum Creatinine

058. Pre-treatment evaluation for Lithium therapy should include:

1. Fasting blood sugar

2. Serum creatinine

3. Liver function tests

4. Platelet count

Answer

2. Serum creatinine

Reference

Katzung 9^th EditionPage 478

Harrison 16^th Edition Page 1703

Quality

Reader

Status

Repeat

QTDF

Harrison

Discussion

Lithium carbonate is the mainstay of treatment in bipolar disorder, although sodium valproate is equally effective in acute mania. Carbamazepine is also efficacious. The response rate to lithium carbonate is 70 to 80% in acute mania, with beneficial effects appearing in 1 to 2 weeks. Lithium also has a prophylactic effect in prevention of recurrent mania, and, to a lesser extent, in the prevention of recurrent depression. A simple cation, lithium is rapidly absorbed from the gastrointestinal tract and remains unbound to plasma or tissue proteins. Some 95% of a given dose is excreted unchanged through the kidneys within 24 h.

Explanation

In the treatment of acute mania, lithium is initiated at 300 mg bid or tid, and the dose is then increased by 300 mg every 2 to 3 days to achieve blood levels of 0.8 to 1.2 meq/L. Before initiating treatment the physician should obtain baseline measures of

Ä electrolytes,

Ä creatinine,

Ä thyroid function, and

Ä a complete blood count (CBC).

Comments

Though this question should come in Psychiatry, Pharmacology or Medicine, I have arranged this question here. This is to maintain the same order the question was asked in the original question paper

Tips

Because the therapeutic effect of lithium may not appear until 7 to 10 days of treatment, adjunctive usage of lorazepam (1 to 2 mg every 4 h) or clonazepam (0.5 to 1 mg every 4 h) may be beneficial to control agitation. Antipsychotics are indicated in patients with severe agitation who respond only partially to benzodiazepines. These agents should be discontinued in the transition to maintenance lithium therapy. Patients using lithium should be monitored closely, since the blood levels required to achieve a therapeutic benefit are close to those associated with neurotoxicity. Risk factors for neurotoxicity include concomitant medical illness, decrease in salt intake, or concurrent use of medications that may increase the serum level of lithium (neuroleptics, diuretics, and calcium channel blockers). Once stabilization is achieved, the lithium level can be monitored on a bimonthly basis, and thyroid and renal functions on a biannual basis, or more frequently if clinical change occurs.