Medication Management

Which Lab Tests Do Psychiatric Medications Need?

By Dr. Stacey Forbes, DNP, APRN, PMHNP-BC · Updated October 12, 2026

Most antidepressants and many anxiety medications need no routine blood tests at all. A smaller group of psychiatric medications does: lithium, valproate and carbamazepine need regular labs because their safety margins are narrower or they can affect the liver, blood cells or kidneys, and antipsychotics need metabolic monitoring for weight, sugar and cholesterol. Clozapine still needs regular white-cell counts even though its federal REMS program ended in 2025. This guide explains what each set of labs is looking for and why skipping them is a real risk.

Safety labs are not the same as functional labs

It helps to separate two kinds of testing. Functional and advanced lab testing looks for things that may be contributing to how you feel, such as thyroid, inflammation, nutrients and hormones. Our article on six lab tests that can change mental health treatment covers that side.

Safety monitoring is different. It is driven by the medication, and the schedule usually comes from the FDA-approved prescribing information. The goal is to catch a known harm, such as a lithium level creeping too high, a liver reaction, a fall in white blood cells or a rise in blood sugar, before it becomes a problem. At Willow & Stone, the two kinds of testing can be planned together, which often means fewer separate blood draws.

The table below is a summary; details for each medication follow. It describes what labels and consensus guidance call for, not target numbers, which your prescriber will interpret for you.

Lithium: levels, kidneys, thyroid and calcium

Lithium is effective and well studied, and it is also the clearest example of why monitoring matters. Its label notes that toxic concentrations are close to the therapeutic range.

Before starting

The label recommends checking kidney function, vital signs, electrolytes and thyroid function, reviewing other medications, and confirming pregnancy status.

During treatment

• Blood levels after any dose change, after starting an interacting drug such as a diuretic, an NSAID like ibuprofen, an ACE inhibitor or ARB blood pressure medicine, or metronidazole, after a marked change in strenuous exercise, and during any significant illness.
• Kidney function, because long-term lithium is associated with chronic kidney disease.
• Thyroid function, regularly, because lithium can cause hypothyroidism.
• Calcium, because long-term lithium is associated with overactive parathyroid glands and high calcium.

Heat, vomiting, diarrhea and dehydration can all raise lithium levels. Our guide on psychiatric medication in extreme heat explains what to watch for in summer.

Valproate and carbamazepine

Valproate (Depakote)

Valproate carries a boxed warning for liver failure, which has usually occurred in the first six months. The label says serum liver tests should be performed before therapy and at frequent intervals afterward, especially during those first six months. It also calls for monitoring platelet counts and clotting tests, and for measuring ammonia if someone develops unexplained lethargy, vomiting or a change in mental status. Platelet problems become more likely at higher blood levels, which is one reason levels are checked. Because valproate can cause serious birth defects, pregnancy planning is part of monitoring for anyone who could become pregnant.

Carbamazepine (Tegretol)

Carbamazepine has two boxed warnings. The first is serious skin reactions, Stevens-Johnson syndrome and toxic epidermal necrolysis, strongly linked to a gene variant called HLA-B*1502. The label says to test for it before starting in patients whose ancestry includes populations where the variant may be present; it is found mainly in people of Asian ancestry. The second is rare aplastic anemia and agranulocytosis, so the label calls for complete pretreatment blood counts including platelets.

During treatment, the label recommends baseline and periodic liver function tests, watches for low sodium, which is more likely in older adults and people on diuretics, and recommends baseline and periodic eye exams, urinalysis and kidney tests. Blood levels may also be used to guide dosing.

Clozapine after the REMS

For years, clozapine could only be dispensed through a federal Risk Evaluation and Mitigation Strategy (REMS) that required white-cell results to be reported before each fill. In an August 2025 Drug Safety Communication, the FDA announced that it had removed the clozapine REMS effective June 13, 2025.

The monitoring itself did not go away. The FDA states that prescribers should continue to check the absolute neutrophil count (ANC) before starting clozapine and during treatment, following the schedule in the prescribing information, and the severe neutropenia warning remains in the boxed warning and a new Medication Guide. The change removed the reporting paperwork, not the safety need. Clozapine’s label also includes boxed warnings for low blood pressure on standing, seizures and myocarditis, and asks for monitoring of glucose, lipids and weight.

Clozapine is a specialized medication. If you take it and are transferring care, make sure your ANC history comes with you.

Antipsychotics: metabolic monitoring

Second-generation antipsychotics can increase weight, blood sugar and lipids. In 2004 the American Diabetes Association and the American Psychiatric Association, with endocrine and obesity groups, published a consensus on monitoring that is still the foundation for practice. A 2024 New York State prescriber education summary adapts it this way:

• At baseline (starting or switching): personal and family history, weight and BMI, waist circumference, fasting glucose or A1c, a lipid panel, and blood pressure and heart rate.
• Weight and BMI again at weeks 4, 8 and 12, then every three months.
• Glucose or A1c, lipids and blood pressure at week 12, then yearly; lipids may be repeated less often in people at lower cardiovascular risk.

The same applies when an antipsychotic is added to an antidepressant. Our guides to antipsychotics as add-on treatment and medication weight gain cover what to do if the numbers move.

ECGs, sodium and stimulant checks

ECG and QTc

Some medications can lengthen the QTc interval, a measure on an ECG that, when prolonged, raises the risk of a dangerous heart rhythm. Citalopram’s label is a useful example: it caps the dose because of QTc prolongation, sets a lower cap for people over 60, says to avoid it with other QTc-prolonging drugs and certain heart conditions, and recommends potassium and magnesium checks and ECG monitoring in higher-risk patients. Several antipsychotics carry similar cautions. An ECG is not routine for everyone, but it is reasonable when there is heart disease, a family history of sudden death, low potassium or magnesium, or more than one QTc-affecting medication.

Sodium on SSRIs

SSRIs can cause low sodium, and the citalopram label says older adults, people on diuretics and those who are volume-depleted are at greater risk. A sodium check after starting or increasing an antidepressant is sensible in those groups.

Stimulants

For ADHD stimulants, monitoring is mostly done in the office rather than the lab. The Concerta label asks prescribers to screen for heart disease before starting, including a family history of sudden death or ventricular arrhythmia, to monitor blood pressure and pulse, and to screen for risk of mania. Home blood pressure readings can be very useful between telehealth visits. See our guide to ADHD medication for adults.

Keeping track without extra burden

Monitoring works only if it happens. A few habits make it easier:

• Keep a simple log of lab dates and results, or ask for copies through your patient portal.
• Ask whether safety labs can be drawn at the same time as any functional tests or labs from your primary care clinician.
• For lithium and valproate levels, ask your prescriber when to time the blood draw relative to your last dose; it changes how the result is read.
• Tell your prescriber about new medications from other clinicians, especially diuretics, blood pressure medicines, NSAIDs and antibiotics.

At Willow & Stone, Dr. Stacey Forbes builds the monitoring schedule into your plan from the first visit and reviews results with you rather than just filing them. To see how monitoring fits the wider integrative medication management approach, or to bring an existing medication list for review, you can book a consultation.

Common Questions

Sources & Further Reading

• DailyMed — Lithium carbonate prescribing information
• DailyMed — Depakote (divalproex sodium) prescribing information
• DailyMed — Tegretol (carbamazepine) prescribing information
• FDA — FDA removes REMS program for the antipsychotic drug clozapine (Drug Safety Communication, Aug 2025)
• New York State Medicaid Prescriber Education Program — Metabolic Monitoring of Antipsychotic Medications (2024)
• DailyMed — Celexa (citalopram) prescribing information
• DailyMed — Concerta (methylphenidate) prescribing information

This article is general education, not advice for your situation. Do not start, stop, or change a medication or supplement without talking to the clinician who prescribes it.