For a child with a history of Disruptive Mood Dysregulation Disorder (DMDD), anxiety, and attentional issues, currently treated with Lexapro (escitalopram), are laboratory tests required as part of the initial psychiatric workup when considering Strattera (atomoxetine)?

Laboratory Testing for Pediatric Psychiatric Workup in a Child with DMDD, Anxiety, and ADHD

No routine laboratory tests are required for this child before starting Strattera (atomoxetine), as long as a thorough history and physical examination with vital signs are normal. 1, 2

Evidence-Based Approach to Laboratory Testing

The most recent and highest-quality guidelines establish that history and physical examination should guide ALL diagnostic decisions, with a pooled yield of 15.6% for detecting clinically significant conditions, while routine laboratory testing has an extremely low yield of only 1.1%. 1

When Labs Are NOT Needed

For a clinically stable child with DMDD, anxiety, and attentional issues already on escitalopram:

• No routine laboratory panels are required before initiating atomoxetine 1, 2
• No routine blood work is mandated by American Academy of Pediatrics or American Academy of Child and Adolescent Psychiatry guidelines for non-stimulant ADHD medications 2
• Routine testing is costly, low-yield, and increases false-positive results 1

Required Pre-Treatment Assessment (Not Labs)

Before starting atomoxetine, you must obtain 2, 3:

• Detailed cardiac history: Family history of sudden death, Wolff-Parkinson-White syndrome, hypertrophic cardiomyopathy, long QT syndrome, or ventricular arrhythmias 2
• Physical examination with vital signs: Blood pressure, heart rate/pulse, height and weight for growth baseline 2
• History of psychotic disorders: Absolute contraindication to stimulants (though atomoxetine is not a stimulant, screen for baseline psychosis/mania risk) 2, 3
• Current medications: Especially MAO inhibitors (absolute contraindication), CYP2D6 inhibitors like paroxetine, or other medications 3, 4
• History of pheochromocytoma: Atomoxetine is contraindicated 3
• Severe cardiovascular disorders: Atomoxetine should not be used if condition would deteriorate with modest BP/HR increases 3

When Labs ARE Indicated

Laboratory testing should be obtained ONLY when indicated by specific findings 1:

• Altered mental status or unexplained vital sign abnormalities 1
• New-onset or acute changes in psychiatric symptoms (not applicable here—chronic DMDD/anxiety) 1
• Abnormal neurologic findings on examination 1
• First symptom or sign of liver dysfunction after starting atomoxetine (pruritus, dark urine, jaundice, right upper quadrant tenderness, unexplained flu-like symptoms) 3

Special Considerations for This Case

Since this child is already on escitalopram:

• No additional labs needed for the combination of atomoxetine plus escitalopram 5
• Monitor blood pressure and pulse more carefully: Combined atomoxetine/SSRI therapy showed greater increases in BP and pulse than atomoxetine alone, though still well-tolerated 5
• The combination is safe and effective: A randomized controlled trial (N=173) demonstrated that atomoxetine combined with fluoxetine was well-tolerated in children and adolescents with ADHD and comorbid anxiety/depression 5

Common Pitfalls to Avoid

• Over-reliance on laboratory testing: History and physical examination are far superior for detecting clinically significant conditions 1
• Ordering "routine" test batteries: This approach is not evidence-based and wastes resources 1
• Inadequate attention to vital signs: Abnormal vital signs are critical predictors of medical pathology and must be documented 1
• Failing to obtain detailed cardiac history: This is the most important screening tool before atomoxetine 2, 3
• Not establishing growth baseline: Height and weight are essential for monitoring atomoxetine's effects on growth over time 2, 6

Monitoring After Initiation

Once atomoxetine is started 2, 3:

• Vital signs should be checked at follow-up visits (not requiring labs) 2
• Monitor for liver dysfunction symptoms: Discontinue immediately if jaundice or laboratory evidence of liver injury develops 3
• Watch for suicidal ideation: Especially in the first month of treatment, though risk is low (0.4% vs 0% placebo) 3, 6
• Growth monitoring: Height and weight at regular intervals, as decreases may occur but appear reversible long-term 6