Thanks to Drs. Gih, Bostwick, and Casher for their valuable reminder about the use of triiodothyronine (T3) in treatment-resistant depression (“Augmenting antidepressants with triiodothyronine: An underutilized strategy,” Current Psychiatry, July 2011, p. 43-44).
The authors note “If TSH [thyroid-stimulating hormone] is elevated, a free thyroxine (T4) level should be ordered to detect clinical hypothyroidism.” I have found a significant number of patients with normal TSH levels but low free T4 levels, which is perhaps because of the number of traumatic brain injuries (TBI) in the veteran population I see. I realize a TSH screening alone is more cost-effective than both a TSH and free T4, but I wonder if this is the best course in evaluating treatment-resistant depression, particularly in patient populations where subtle brain damage may confound a normal TSH value. How many cases of hypothyroidism might be missed in the interest of economy?
Scott D. Mendelson, MD, PhD
Consultation Liaison Psychiatrist
Roseburg VA Medical Center
Roseburg, OR
The authors respond
Thank you for your interest in our article. Our opinion is TSH alone is a sufficient screening laboratory in “routine” depressed populations. Although a case could be made for adding free T4 (with TSH), economics and clinical guidelines would argue otherwise. In patients who are asymptomatic but have abnormal thyroid values, referral to an endocrinologist is highly advised.
Although we do not routinely see brain traumatized patients, a 2007 article by Rothman et al1 affirms your astute clinical observations about TBI and associated neuroendocrine findings.
Many clinicians are checking and supplementing vitamin D levels, in addition to including omega-3 fatty acids in their psychotropic regimens. Although the jury remains out on these interventions, preliminary data suggest these may be helpful adjuncts for depressed patients and have a low burden of side effects. Let us not forget that evidence-based psychotherapies also should be included in the armamentarium for treating “resistant” depressed patients. Psychosocial interventions should be given the same “adequate dose and duration” guidance as psychotropics.
Daniel E. Gih, MD
Clinical Assistant Professor of Child
and Adolescent Psychiatry
Department of Psychiatry
University of Michigan Health System
Ann Arbor, MI
Jolene Bostwick, PharmD, BCPS, BCPP
Clinical Assistant Professor of Pharmacy
Clinical Pharmacist
University of Michigan Health System
Ann Arbor, MI
Michael I. Casher, MD
Clinical Assistant Professor of Psychiatry
Director, Adult Inpatient Unit
University of Michigan Health System
Ann Arbor, MI