Attention Deficit Hyperactivity Disorder (ADHD) Workup

Updated: Mar 31, 2022
  • Author: Stephen Soreff, MD; Chief Editor: Glen L Xiong, MD  more...
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Approach Considerations

The diagnosis requires the symptoms of ADHD to be present both in school and at home. Furthermore, all patients must have a full psychiatric evaluation and physical examination. Here is a cautionary note underscoring the need for a full assessment for late-onset ADHD in adolescents and young adults.

Adolescents and young adults without childhood ADHD often present to clinics seeking stimulant medication for late-onset ADHD symptoms and there is, indeed, a valid diagnosis of late-onset ADHD in many cases. However, diagnosis based on the traditional parameters for ADHD may be incomplete in their ability to make the proper determination. Researchers have found that a more thorough psychiatric history is called for.

In one study, researchers administered 8 assessments to 239 individuals without childhood ADHD. Assessments included parent, teacher, and self-reports of ADHD symptoms, impairment, substance use, and other mental disorders, with consideration of symptom context and timing. Results show that of the individuals who initially screened positive on symptom checklists, 95% were excluded from late-onset ADHD diagnosis. The most common reason for diagnostic exclusion was symptoms or impairment occurring exclusively in the context of heavy substance use. These findings suggest that clinicians should consider alternative causes of symptoms and carefully assess impairment, psychiatric history, and substance use. [30]


Laboratory Studies

The diagnosis of attention deficit hyperactivity disorder (ADHD) is based on clinical evaluation. No laboratory-based medical tests are available to confirm the diagnosis.

Basic laboratory studies that may help confirm diagnosis and aid in treatment are as follows:

  • Serum CBC count with differential

  • Electrolyte levels

  • Liver function tests (before beginning stimulant therapy)

  • Thyroid function tests


Imaging Studies

Brain imaging, such as functional MRI or single photon emission computed tomography (SPECT) scans have been useful for research, but no clinical indication exists for these procedures because the diagnosis is clinical.

However, in the largest imaging study of ADHD conducted to date, investigators found that five regions of the brain were slightly smaller in children with ADHD compared to children without the disorder. The study included 1713 individuals with ADHD and 1529 unaffected controls. Participants ranged in age from 4 years to 63 years (median age, 14 years). Researchers used MRI scans to assess the differences in the subcortical structures and intracranial volume of patients' brains. Patients with ADHD were found to have reductions in the volumes of the accumbens, the amygdala, the caudate, the hippocampus, and the putamen, as well as reductions in intracranial volume. Effect sizes were highest in most subgroups of children (< 15 years) versus adults (>21 years). [31]


Other Tests

The Conners Parent-Teacher Rating Scale is a questionnaire that can be given to both the parents and the child's teachers.

Barkley Home Situations Questionnaire may be useful.

The Wender Utah Rating Scale may be helpful in diagnosing ADHD in adults. In 2017, a new machine-learning algorithm was used to build a screening scale from responses to 6 questions in the World Health Organization (WHO) Adult Attention-Deficit/Hyperactivity Disorder Self-Report Scale (ASRS) using optimal integer scoring rules. The new measure is short, easily scored, and detects the vast majority of general population cases. [32]

The Continuous Performance Tests (CPTs) are computer-based tasks that often are used to test attention and may be used in conjunction with clinical information to make a diagnosis. A currently popular example is the Test of Variable Attention (TOVA). While these tests can be supportive of the diagnosis in a full clinical evaluation, they have low sensitivity and specificity and should not be the sole basis for diagnosis.

Vision and hearing should be checked.