Final answer:
The patient presenting with a history of fluctuating mood episodes and a family history of psychotic highs is at increased risk for hypomania if treated with a tricyclic antidepressant.
Step-by-step explanation:
The patient's history of episodes of fatigue, poor concentration, decreased appetite, and decreased interest in usual activities, combined with periods of increased energy and a family history of 'psychotic highs,' suggest a possible mood disorder such as bipolar disorder. If this patient is treated with a tricyclic antidepressant, she would be at increased risk for hypomania (C). This is because tricyclic antidepressants can precipitate manic or hypomanic episodes in patients with bipolar disorder. It is crucial to properly diagnose a patient before prescribing antidepressants, as the risk of inducing a switch into mania or hypomania is an acknowledged concern in bipolar disorder treatment.