Most medications used to treat mental disorders do not require blood level monitoring. This is mainly due to the inconsistency and heterogeneity of responses to different doses of psychiatric medications.
Only a few medications have sufficient evidence suggesting a therapeutic range and threshold for toxicity. In fact, blood level monitoring is used more for preventing toxicity than ensuring therapeutic efficacy.
Lithium has a narrow therapeutic index, which means the threshhold for therapeutic effect and toxicity are close together. The normal therapeutic blood level for lithium is between 0.6-1.2.
Valproic acid (Depakote) does not have an agreed upon therapeutic level, but most experts report toxic effects with blood levels over 150.
Clozapine does not require monitoring of drug levels per se, but instead requires repeated neutrophil counts because neutropenia (i.e., low white blood cells) and agranulocytosis are rare yet serious adverse effects of clozapine treatment.
Below is a table outlining the most common medications requiring blood level monitoring, their recommended therapeutic ranges, and the recommended frequency of monitoring.
|Antipsychotics||---||▪Baseline/yearly: CBC, CMP, Hba1c, TSH, Lipid panel|
|▪Consider Baseline EKG|
|Clozapine||---||▪Same as above (except CBC scheduling)|
|▪CBC (ANC) Schedule:|
|Check at baseline, weekly for 6 months, then biweekly for 6 months, then monthly after 1 year|
|Lithium||▪Acute: 0.8-1.2mEq/L||▪Baseline/2-3x per year: CBC, Cr, BUN, TSH, CMP|
|▪Chronic: 0.50-0.75mEq/L||▪Consider baseline EKG in pts >50yo|
|▪Check Li levels after 4-5 half lives (blood should be collected prior to next dose)|
|▪Recheck Li levels after dose changes, addition of other drugs, or if suspecting toxicity|
|Valproic acid||▪ 45-125ug/ml||▪Baseline/q6-12mos: CBC, LFTs, Electrolytes, TSH|
|(Manic patients may require/ tolerate higher levels)|
|Carbamazepine||---||▪Baseline: Na, CBC, BUN, Cr, LFTs, TSH|
|▪Follow CBC and Na q2-4wks for 8 wk then q3-6mos|
|▪Follow BUN, Cr, LFTs, and TSH q6-12mos|
|SNRIs, Bupropion, TCAs, MAOIs||---||▪Monitor blood pressure & HR|
*(—) No definitive evidence correlating levels with efficacy
Lithium Level Monitoring
|Lithium Monitoring||Target Lithium Level||Recommended Labs|
|Acute Mania||0.8-1.2mEq/L||Baseline: CBC, CMP, Cr, BUN, TSH, Weight, EKG (in pts>50yo or with cardiac disease)|
|Maintenance||0.6-1.0 mEq/L||After 1 week, 1 month, 6 months, and 12 months of starting lithium: Lithium Level, TSH, BUN/Cr, Electrolytes, monitor weight|
|Every 6-12 months: Lithium Level, TSH, BUN/Cr, Electrolytes, monitor weight|
|NOTE: Check Lithium levels after 4-5 half lives (blood should be collected prior to next dose); Also check lithium levels after dosage changes, addition of other drugs, or if suspecting toxicity|
Clozapine & Absolute Neutrophil Count (ANC) Monitoring
- J. Ferrando, J. L. Levenson, & J. A. Owen (Eds.), Clinical manual of psychopharmacology in the medically ill(pp. 3-38). Arlington, VA, US: American Psychiatric Publishing, Inc.
- Stahl, S. M. (2014). Stahl’s essential psychopharmacology: Prescriber’s guide (5th ed.). New York, NY, US: Cambridge University Press.
- McCarron, Robert M., et al. Lippincotts Primary Care Psychiatry: for Primary Care Clinicians and Trainees, Medical Specialists, Neurologists, Emergency Medical Professionals, Mental Health Providers, and Trainees. Wolters Kluwer Health/Lippincott Williams & Wilkins, 2009.
- Focus Psychiatry Review, Dsm-5: Dsm-5 Revised Edition by Deborah J. Hales (Author, Editor), Mark Hyman Rapaport (Author, Editor)
- Cooper, J. R., Bloom, F. E., & Roth, R. H. (2003). The biochemical basis of neuropharmacology (8th ed.). New York, NY, US: Oxford University Press.
- Iversen, L. L., Iversen, S. D., Bloom, F. E., & Roth, R. H. (2009). Introduction to neuropsychopharmacology. Oxford: Oxford University Press.
- Levenson, J. L. (2019). The American Psychiatric Association Publishing textbook of psychosomatic medicine and consultation-liaison psychiatry. Washington, D.C.: American Psychiatric Association Publishing.
- Schatzberg, A. F., & DeBattista, C. (2015). Manual of clinical psychopharmacology. Washington, DC: American Psychiatric Publishing.
- Schatzberg, A. F., & Nemeroff, C. B. (2017). The American Psychiatric Association Publishing textbook of psychopharmacology. Arlington, VA: American Psychiatric Association Publishing.
- Stahl, S. M. (2013). Stahl’s essential psychopharmacology: Neuroscientific basis and practical applications (4th ed.). New York, NY, US: Cambridge University Press.
- Stern, T. A., Freudenreich, O., Fricchione, G., Rosenbaum, J. F., & Smith, F. A. (2018). Massachusetts General Hospital handbook of general hospital psychiatry. Edinburgh: Elsevier.
- Whalen, K., Finkel, R., & Panavelil, T. A. (2015). Lippincotts illustrated reviews: pharmacology. Philadelphia, PA: Wolters Kluwer.
- Hales et al. The American Psychiatric Association Publishing Textbook of Psychiatry. 6th
- Goldberg & Ernst. Managing Side Effects of Psychotropic Medications. 1st 2012. APP.
- Benjamin J. Sadock, Virginia A. Sadock. Kaplan & Sadock’s Comprehensive Textbook of Psychiatry. Philadelphia :Lippincott Williams & Wilkins, 2000.
- Ebenezer, Ivor. Neuropsychopharmacology and Therapeutics. John Wiley & Sons, Ltd. 2015.
- Puzantian, T., & Carlat, D. J. (2016). Medication fact book: for psychiatric practice. Newburyport, MA: Carlat Publishing, LLC.
- Meyer, Jerrold, and Quenzer, Linda. Psychopharmacology: Drugs, the Brain, and Behavior. Sinauer Associates. 2018.