Section 6: The Medical Workup: Ruling Out Organic Mimics

Before confirming a primary psychiatric diagnosis of bipolar disorder, the clinician should exclude medical conditions that can produce manic-like symptoms. The medical workup also establishes baseline parameters for the medication treatment that will follow diagnosis.

6.1 Medical Conditions That Mimic Mania

Several medical conditions can present with symptoms indistinguishable from primary mania.

**Hyperthyroidism. **The most important organic mimic to exclude. An overactive thyroid (thyrotoxicosis) produces rapid heart rate, weight loss, tremor, anxiety, restless agitation, insomnia, and irritability, all of which overlap with manic presentation. Thyroid function testing (TSH) is universally mandated as the single most important endocrine test in bipolar evaluation, serving the dual purpose of ruling out thyroid-driven mood disturbance and establishing a baseline before lithium therapy, which frequently induces underactive thyroid function (BAP 2016, Goodwin et al., Journal of Psychopharmacology; NICE CG185).

**Cushing's syndrome. **Excess cortisol production (hypercortisolism) produces mood lability, irritability, anxiety, and psychosis that can closely resemble bipolar presentation. Corticosteroids directly influence the body's stress hormone system (HPA axis) and alter brain chemical signaling.

**Multiple sclerosis. **MS lesions in the frontal and temporal lobes can produce euphoria, disinhibition, and mood instability that mimic mania. New-onset psychiatric symptoms in a young adult, particularly when accompanied by neurological findings, should prompt neuroimaging.

**Traumatic brain injury (TBI). **TBI-associated mania occurs through disruption of brain circuits connecting the frontal and temporal lobes. Any acute psychiatric presentation following head trauma warrants neuroimaging.

**Anti-NMDA receptor encephalitis. **This autoimmune condition, in which the body's immune system attacks a specific receptor in the brain, presents with psychiatric symptoms (psychosis, agitation, mood instability) that can dominate the early clinical picture before neurological features emerge. It is particularly relevant in young women and should be considered when psychiatric presentation includes altered consciousness, movement abnormalities, or rapid cognitive decline.

**Delirium. **In acute medical settings, delirium with hyperactive features (agitation, disorientation, fluctuating consciousness) can be mistaken for acute mania, particularly in older adults or patients with medical comorbidities.

6.2 The Minimum Medical Workup

Synthesizing recommendations across the major guidelines, the following laboratory battery reflects BAP's explicit pre-treatment baseline checklist and is broadly consistent with the evaluation recommendations of NICE, CANMAT, and VA/DoD, though each guideline differs slightly in which specific tests it explicitly mandates versus implies (BAP 2016, Goodwin et al., Journal of Psychopharmacology; NICE CG185; VA/DoD 2023):

**Complete blood count (CBC) with differential. **Rules out infection-driven altered mental status and severe anemia mimicking bipolar depression.

**Comprehensive metabolic panel (CMP). **This panel covers several critical checks. Electrolytes rule out low sodium (hyponatremia) and high calcium (hypercalcemia), both of which cause neuropsychiatric symptoms that can mimic mood disorders. Renal function (BUN/creatinine) is a prerequisite before lithium initiation, because lithium is cleared entirely by the kidneys and has a very narrow margin between a therapeutic dose and a toxic one. Liver function tests are a prerequisite before valproate or carbamazepine, which carry risk of liver damage.

**Fasting glucose/HbA1c and fasting lipid panel. **Establishes cardiometabolic baseline before initiating second-generation antipsychotics, which carry significant risk of metabolic syndrome (a cluster of conditions including weight gain, elevated blood sugar, and abnormal cholesterol levels), abnormal lipid levels, and medication-induced diabetes.

**Thyroid function tests (TSH). **Universally mandated. Rules out hyperthyroidism (mimics mania) and hypothyroidism (mimics or exacerbates depression). Establishes baseline for lithium monitoring.

**Toxicology screen (urine drug screen and blood alcohol level). **Rules out substance-induced mood disorders. Stimulant intoxication (cocaine, amphetamines) and synthetic cannabinoids can replicate acute mania.

**Pregnancy test (serum or urine beta-hCG). **Mandatory for all female patients of childbearing potential. Valproate carries severe risk of birth defects (particularly neural tube defects such as spina bifida), and lithium carries risk of a specific heart defect called Ebstein's anomaly, requiring absolute confirmation of pregnancy status before prescribing.

In plain language for families: Before starting medication for

bipolar disorder, doctors need to run blood tests. These tests do two things at once. First, they check whether a medical condition like a thyroid problem might be causing the mood symptoms, because an overactive thyroid can look exactly like mania, and an underactive thyroid can look like depression. Second, they establish a "starting point" for the body's kidney function, liver function, blood sugar, and cholesterol, because the medications used to treat bipolar disorder can affect all of these over time. If your doctor orders these tests, it does not mean something else is wrong. It means they are being thorough about both the diagnosis and the safety of the treatment plan.

6.3 Indication-Driven Additional Testing

Beyond the minimum workup, the patient's history and examination dictate further investigations:

• ECG: Recommended for patients over 40, those with cardiovascular history, or before initiating medications known to prolong the QTc interval (a measure of the heart's electrical recovery time; prolongation increases the risk of dangerous heart rhythm abnormalities), including lithium and specific antipsychotics like ziprasidone

• Serum prolactin: When initiating antipsychotics known to cause hyperprolactinemia (abnormal elevation of the hormone prolactin, which can cause menstrual irregularities, breast enlargement, or sexual dysfunction), particularly risperidone and paliperidone

• Neuroimaging (MRI/CT brain): Indicated for new-onset mania in patients over 50, focal neurological deficits, post-TBI presentations, or highly atypical psychiatric presentations (treatment refractoriness, visual or olfactory hallucinations)

• CSF analysis and EEG: When autoimmune encephalitis, infectious meningoencephalitis, or seizure-related psychosis is suspected

6.4 Pediatric Considerations

The medical evaluation of early-onset bipolar disorder carries specific requirements. AACAP and AAP mandate multidisciplinary, prospective longitudinal observation by a child psychiatrist rather than cross-sectional single-visit diagnosis. Pediatric populations show heightened sensitivity to the metabolic effects of atypical antipsychotics, requiring more rigorous and frequent metabolic monitoring (weight, lipid profiles, HbA1c) (AACAP Practice Parameter, 2007, JAACAP).

6.5 Older Adult Considerations

Evaluating bipolar disorder in adults over 50 presents distinct challenges. New-onset mania after age 50 is more frequently secondary to medical conditions (cerebrovascular disease, neurodegenerative disorders, medications) than in younger patients, and neuroimaging should be strongly considered for any first manic episode in this age group. Cognitive impairment, which may reflect neuroprogression from longstanding bipolar illness or comorbid neurodegenerative disease, can confound mood assessment and functional evaluation.

Standard functional assessments used in general psychiatry often focus on occupational performance, which is irrelevant for retired individuals. The ISBD Task Force on Older Adult Bipolar Disorder recommends the FAST-O (Functioning Assessment Short Test for Older Adults with Bipolar Disorder), a validated tool that replaces workplace metrics with societal and volunteer functioning domains to provide a more accurate picture of daily performance.

Pharmacotherapy in older adults also requires adjusted evaluation targets. The ISBD Delphi consensus recommends that for patients aged 60-79, the therapeutic lithium serum level target should be 0.4 to 0.8 mmol/L, lower than the 0.6-1.0 mmol/L range used in younger adults, to reduce the risk of neurotoxicity (Shulman et al., 2019, Bipolar Disorders). Baseline evaluation should include careful assessment of renal function, cognitive status, and medication interactions, as polypharmacy is common in older populations.

Clinical Pearl: The Primary Care Medical Workup as a Referral

Accelerator A practical workflow consideration rather than a specific guideline recommendation: if you suspect bipolar disorder in a depressed patient and plan to refer to psychiatry, ordering the baseline medical workup concurrently with the referral can significantly expedite care. Having TSH, metabolic panel, renal function, lipid panel, and ECG results ready allows the receiving psychiatrist to initiate mood-stabilizing pharmacotherapy without additional delay. This is especially valuable in settings where the referral wait time for psychiatry is measured in weeks or months.

Section 7: Primary Care Recognition: When to Suspect Bipolar in a

Depressed Patient

The majority of patients with bipolar disorder make their initial clinical presentation not to a psychiatrist, but to a primary care physician, nurse practitioner, pediatrician, or therapist. Translating the diagnostic framework into practical decision rules for these clinicians is essential for reducing the 5-to-10-year diagnostic delay.

7.1 The Clinical Red Flags

Seven clinical features should raise suspicion for an underlying bipolar diathesis (a biological predisposition toward bipolar disorder) in a patient presenting with depression. These are not diagnostic, but each significantly raises the likelihood that the depression is part of a bipolar pattern.

Red Flag 1: Antidepressant non-response (two or more adequate trials). A patient who has not responded to two or more adequate SSRI/SNRI trials may have unrecognized bipolar depression. Bipolar depression is characteristically resistant to antidepressant monotherapy because the underlying disease mechanism is fundamentally different from unipolar MDD. Persistent non-response to antidepressants is one of the most common clinical pathways that eventually reveals a bipolar diagnosis.

Red Flag 2: Antidepressant-associated mood elevation or agitation. When a patient starts an SSRI and rapidly develops unusual energy, irritability, insomnia, racing thoughts, pressured speech, or grandiosity, this is rarely a standard medication side effect. It is very likely the diagnostic unmasking of latent bipolar disorder. The evidence on whether youth are at higher risk than adults for antidepressant-induced manic switch is mixed: some observational data suggests modestly elevated risk in younger patients (Martin et al., 2004, Archives of Pediatrics and Adolescent Medicine), while RCT data shows low absolute rates and a recent large cohort study found no increased incidence compared to untreated youth (Martin et al., 2004; AACAP Practice Parameter, 2007). Regardless of the comparative magnitude, close monitoring for mood elevation is essential when initiating antidepressants in pediatric populations, and the threshold for suspecting bipolar unmasking should be low in any young patient who develops activation symptoms on an antidepressant.

**Red Flag 3: Highly recurrent depression (three or more episodes). **A patient with multiple recurrent depressive episodes, particularly five or more, has a substantially elevated probability of an underlying bipolar spectrum condition. Highly recurrent depression is one of the CANMAT features "suggestive of bipolarity" (CANMAT/ISBD 2018, Yatham et al., Bipolar Disorders).

**Red Flag 4: Early-onset depression (before age 25). **The earlier the first depressive episode, the higher the probability of eventual bipolar conversion. This is one of the strongest longitudinal predictors (Hedges' g = -0.33).

**Red Flag 5: Psychotic depression. **The presence of psychotic features during a depressive episode is among the strongest predictors of bipolar conversion (pooled OR = 4.76, 95% CI: 1.79-12.66).

**Red Flag 6: Family history of bipolar disorder. **A positive first-degree family history of bipolar disorder carries a pooled OR of 2.89 (95% CI: 2.01-4.14) for eventual bipolar diagnosis. This is one of the most accessible and reliable clinical data points.

**Red Flag 7: Postpartum mood episode. **Severe depression or psychosis with onset in the postpartum period has a strong association with bipolar spectrum disorders and should prompt careful evaluation for a history of mood elevation (CANMAT/ISBD 2018, Yatham et al., Bipolar Disorders).

7.2 When to Refer to Psychiatry

While stable, well-characterized bipolar disorder can be co-managed with psychiatry, certain presentations require direct psychiatric evaluation:

• First episode of suspected mania or hypomania

• Psychotic features in any mood state

• Mixed features (concurrent manic and depressive symptoms)

• Active suicidality or recent suicide attempt

• Rapid cycling (four or more mood episodes per year)

• Inadequate response to two or more mood-stabilizing medications

• Pregnancy or planned pregnancy in a patient on mood stabilizers

• Diagnostic uncertainty between bipolar disorder and BPD or schizoaffective disorder

NICE CG185 specifies that any patient presenting in primary care with depression who reports a history of overactivity or disinhibited behavior lasting four or more days should be referred for specialist mental health assessment (NICE CG185).

In settings where psychiatric referral waitlists are long, primary care providers may need to take interim measures while awaiting specialist evaluation: complete the minimum medical workup described in Section 6 so that results are available when the specialist appointment occurs, conduct a safety assessment (particularly for suicidality, which is covered in Section 4.6), exercise caution about initiating or continuing antidepressant monotherapy if bipolar disorder is suspected, and schedule closer follow-up intervals to monitor for mood destabilization. The decision to initiate a mood stabilizer in the absence of specialist consultation depends on the clinical urgency and the provider's comfort level, and is beyond the scope of this evaluation module (see Module 3 for pharmacotherapy guidance).

An additional consideration: the evaluation approaches described in this module were developed and validated primarily in English-speaking, Western research populations. Cultural norms around emotional expression may affect how patients describe mood states, and screening instruments have variable validation across languages. The collateral history approach (Pillar 2) assumes family accessibility and willingness to participate, which varies across cultural contexts. Clinicians serving diverse populations should be aware of these limitations and adapt their approach accordingly.

7.3 The Primary Care Provider's Ongoing Role

For patients diagnosed and stabilized by psychiatry, primary care plays a critical ongoing role in metabolic and medication monitoring:

**Metabolic monitoring for atypical antipsychotics. **Second-generation antipsychotics carry significant metabolic risk. Primary care should monitor weight, fasting glucose/HbA1c, and fasting lipids at regular intervals per guidelines. This monitoring is often more effectively managed in primary care than in psychiatry due to visit frequency and access to laboratory infrastructure.

**Lithium monitoring. **Lithium requires ongoing monitoring of serum levels (therapeutic range typically 0.6-1.0 mmol/L for acute treatment, 0.4-0.8 mmol/L for maintenance, with lower targets of 0.4-0.8 mmol/L recommended for patients aged 60-79 to avoid neurotoxicity) (Shulman et al., 2019, Bipolar Disorders; BAP 2016, Goodwin et al., Journal of Psychopharmacology). Renal function and thyroid function should be monitored at baseline and at regular intervals given lithium's nephrotoxic potential and its tendency to induce hypothyroidism.

**Medication adherence. **Non-adherence is the most common cause of bipolar relapse. Primary care providers who see patients more frequently than psychiatrists are well positioned to detect early signs of non-adherence and to address barriers.

In plain language for families: If you are seeing a family doctor,

nurse practitioner, or therapist about depression, and the depression has come back multiple times, started young (before age 25), does not get better with antidepressants, or runs in a family where someone has bipolar disorder, these are signs that the depression might be part of a bipolar pattern rather than straightforward depression. This does not mean you definitely have bipolar disorder. It means the doctor should look more carefully, ask detailed questions about past periods of high energy or unusual behavior, and consider whether a specialist evaluation is needed. Catching this early changes the treatment plan and can prevent years of being on the wrong medications.

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Medical Workup & Primary Care Recognition