Screening Labs

Depression (treatment resistant)

BASIC

TSH, LFT, Chem 10 (fasting), CBC, Ferritin, Folate, B12, Vitamin D (25-hydroxy), hs-CRP

OPTIONAL

Men: Morning total testosterone level (if depression, low energy, or low libido)
Women: Consider menopausal status but do not check female hormones
If at risk: Lyme, RPR, HIV-1/2 antigen/antibody, Syphilis (treponemal test, refer for CSF if reactive), urine drug screen

Psychosis (new onset)

BASIC

TSH, LFT, Chem 10, phosphorus, CBC, Folate, B12, Urine toxicology (drug screen)
Fasting lipids and hgba1c as a screen for antipsychotics

OPTIONAL

Risk for STDs: HIV-1/2 antigen/antibody, Syphilis (treponemal test, refer for CSF if reactive)
Delirium: Urinalysis
Liver disease or neurologic signs: Ceruloplasmin (to evaluate for Wilson’s disease, ie copper toxicity)
Autoimmune, or inflammatory disease: Antinuclear antibodies (ANA) and erythrocyte sedimentation rate (ESR)
Postpartum, neurologic signs, or autoimmune encephalitis suspected: Anti-NMDA antibody
Heavy metal exposure: Test levels (lead, mercury, arsenic, cadmium, thallium), eg exposure from houses built before 1978, industrial work, poisoning.

REFER OUT

Lumbar puncture, neuroimaging (MRI preferred over CT), and EEG when encephalitis, structural abnormality, or seizures are suspected.

Alcohol use disorder

SCREEN FOR DAMAGE

LFT, PT/INR, Chem 10, phosphate, CBC with differential, fasting lipids, hgba1c, B12, folate, Vitamin D (25-hydroxy),
Other causes of liver disease and STDs that travel with addiction: Hepatitis B triple panel (HBsAg, anti-HBs, total anti-HBc), Hepatitis C antibody with reflex RNA,HIV-1/2 antigen/antibody
GGT is optional, and is a more sensitive test for liver injury
Calculate the fibrosis level (FIB-4) from LFT and PLT

SCREEN FOR EXCESS USE

PEth (phosphatidylethanol) is the best. It reflects drinking over the past 2–5 weeks and isn’t affected by liver or kidney disease, age, sex, or BMI.

Dementia

BASIC

MOCA testing in office, Thinc-IT app at home (every few months)
TSH, LFT, Chem 10, CBC, Ferritin, Folate, B12
Calculate anticholinergic burden in med list

OPTIONAL

Alcohol use, malnutrition, or bariatric surgery: Methylmalonic acid (MMA), make the thiamine “whole blood” (and give B12 oral before testing), copper, ceruloplasmin, zinc, vitamin E
Renal disease: Magnesium, phosphorous
Liver disease: INR, platelets, ammonia; FIB-4 if cirrhosis status is unclear
Autoimmune disease: ESR, CRP, ANA ± ANCA; anti-TPO if Hashimoto encephalopathy (SREAT) is suspected
Known cancer: Paraneoplastic antibody panel (serum ± CSF); SPEP/UPEP
Risk for STDs: HIV-1/2 antigen/antibody, Syphilis (treponemal test, refer for CSF if reactive)

REFER OUT

Refer patients with suspected dementia to neurology for further testing, although you can start basic work-up while waiting that or if symptoms are mild. More timely referral is needed if rapid decline, unusual symptoms (eg delirium, psychosis), or neurologic signs (eg, unsteady gait). Neurology may perform:

Brain imaging: Noncontrast MRI is preferred; CT if MRI isn’t possible

Lumbar puncture and antibody panels

ALZHEIMER RISK

These tests, newly cleared in 2025, assess for risk but do not screen for reversible causes. Order only after the medical workup is done.

Lumipulse pTau217/Aβ42 ratio: for symptomatic adults
Elecsys pTau181: as a rule-out test in primary care

Comprehensive Metabolic Panel (14): LFTs, electrolytes, calcium

Basic Metabolic Panel (8): Electrolytes, calcium

Medication Labs

Antipsychotics

Fasting lipid panel and hgba1c
Prolactin if on risperidone, paliperidone, amisulpride, or breast enlargement

Lithium

Lithium, TSH, Basic metabolic panel (8)

Valproate

Valproate, LFT, CBC with PLT
Women: Pregnancy test required at start and periodically
If mental status change or confusion: Ammonia
If symptoms of pancreatitis: Lipase
If intellectual or developmental disability: Check POLG before starting it (high risk of liver injury if mitochondrial disease)
Target trough 50–100 for maintenance, 90-125 mcg/mL if manic

Carbamazepine

BASIC

Carbamazepine, TSH, Comprehensive metabolic panel (14), CBC with PLT, Vitamin D (25-hydroxy)
Check serum level 5-7 days after reaching stable dose, then again 3-5 weeks later (it tends to drop at that point due to autoinduction)
If Asian descent: Check HLA*B15:02 before starting it; do not start if positive (high rash risk)
Target trough: 4–12 mcg/mL, but dose by symptoms not serum level