What is the most appropriate test to order for a non-compliant adult patient with a history of Diabetes Mellitus (DM), Hypertension (HTN), Atrial Fibrillation (AF), depression, and anxiety, presenting with irritability and mood swings, currently taking medications for DM, HTN, and Amiodarone (amiodarone)?

Most Appropriate Test: TSH (Thyroid-Stimulating Hormone)

The most appropriate test to order is TSH, as amiodarone commonly causes thyroid dysfunction that can present with psychiatric symptoms including irritability and mood swings, and this is a critical medication-specific complication that requires monitoring. 1

Rationale for TSH Testing

Amiodarone-Induced Thyroid Dysfunction

• Amiodarone is well-known to cause both hyperthyroidism and hypothyroidism due to its high iodine content and direct effects on thyroid hormone metabolism 1
• Thyroid dysfunction from amiodarone can manifest with neuropsychiatric symptoms including irritability, mood swings, anxiety, and depression—symptoms that overlap significantly with this patient's presentation 1
• The patient's psychiatric symptoms (irritability, mood swings) combined with amiodarone use makes thyroid dysfunction a high-probability diagnosis that must be ruled out first 1

Clinical Context Supporting TSH Priority

• The patient has multiple risk factors for thyroid dysfunction: female gender, older age (implied by multiple comorbidities), and amiodarone therapy 2, 3
• Non-compliance with medications may have led to erratic amiodarone dosing, potentially triggering thyroid dysfunction 1
• Thyroid disorders are particularly important to screen for in patients with pre-existing depression and anxiety, as thyroid dysfunction can exacerbate these conditions 4, 2

Why Not LFT as First Priority

While liver function monitoring is important for patients on amiodarone, LFT abnormalities typically do not present with isolated psychiatric symptoms like irritability and mood swings:

• Amiodarone-related hepatotoxicity usually presents with elevated transaminases that may be asymptomatic or associated with non-specific symptoms like fatigue 1
• Psychiatric manifestations are not the primary presenting feature of amiodarone hepatotoxicity
• LFT monitoring is important but should be part of routine amiodarone surveillance rather than the immediate diagnostic priority for this specific presentation 1

Comprehensive Approach to This Patient

Immediate Testing Priority

1. TSH with reflex free T4 - to evaluate for amiodarone-induced thyroid dysfunction 2, 3, 1
2. Consider adding free T3 if TSH is abnormal, as amiodarone can cause complex thyroid hormone alterations 1

Secondary Testing Considerations

• LFT should be checked as part of routine amiodarone monitoring, but is not the primary test for this presentation 1
• Hemoglobin A1C to assess diabetes control, as poor glycemic control can contribute to mood symptoms 4, 2
• Comprehensive metabolic panel to evaluate electrolytes and renal function, particularly important given non-compliance with DM and HTN medications 2, 5
• Depression screening tools should be employed given the history of depression and anxiety 4

Common Pitfalls to Avoid

• Attributing all psychiatric symptoms to pre-existing depression/anxiety without ruling out medical causes, particularly medication-induced thyroid dysfunction 4, 1
• Ordering LFT first when psychiatric symptoms are the primary complaint—this misses the more likely diagnosis of thyroid dysfunction 1
• Failing to recognize amiodarone's unique thyroid effects that can occur at any time during therapy, not just at initiation 1
• Not considering medication non-compliance as a trigger for metabolic decompensation that could manifest with neuropsychiatric symptoms 4

Clinical Algorithm

Step 1: Order TSH immediately given amiodarone use and psychiatric presentation 2, 3, 1

Step 2: If TSH is abnormal, add free T4 and free T3 to characterize the thyroid dysfunction 1

Step 3: Simultaneously order routine monitoring labs (LFT, CMP, A1C) as part of comprehensive assessment of medication non-compliance 2, 5

Step 4: If thyroid function is normal, pursue other causes including uncontrolled diabetes, electrolyte abnormalities, or primary psychiatric decompensation 4, 2