Thyroid Stimulating Hormone in Acute Psychiatric Patients with Positive Urine Toxicology Drug Screen: A Retrospective Study

Abstract

Background: The effect of recent exposure to illicit substances on the hypothalamic-pituitary-thyroid axis hormones during acute psychiatric hospitalization remains largely unknown. The aim of this study was to examine thyroid stimulating hormone (TSH) levels in patients admitted to the Los Angeles County hospital psychiatric emergency room with positive urine toxicology screening [Utox(+)]. Methods: The medical records of all patients admitted to the psychiatric emergency room (ER) (2002-2007) were reviewed (n=18,836) to extract TSH and Utox data. Serum TSH levels are routinely measured by radioimmunoassay and Utox is routinely tested using the enzyme immunoassay technique as part of clinical care. A general linear model was used to compare geometric mean TSH values between Utox(+) and Utox(-) groups adjusting for age, sex, and race. Results: Utox data were available for 57% (n=4,470) of final study cohort. 39% (n=1,726) were Utox(+). A significant race effect on TSH levels was detected regardless of Utox(+) status, with African American patients having significantly lower mean TSH compared with non-Hispanic white patients: 0.98 ± 2.19 vs. 1.29 ± 2.43, mean ± SD, P<0.0001). Furthermore, TSH levels were significantly lower in the Utox(+) group compared with the Utox(-) group (1.01 ± 2.41 vs. 1.26 ± 2.26, P<0.0001) adjusted for age, gender, and race. Within the Utox(+) group, there was no significant gender difference observed (males vs. females: 1.00 ± 2.32 vs. 1.04 ± 2.57, P=0.1). Conclusion: We observed an association between Utox(+) status and low serum TSH levels in both males and females admitted for acute psychiatric conditions. While the stress caused by acute substance intoxication or withdrawal may play a role in altering TSH levels in this group of patients, the neuroendocrinological underpinnings of this observation require further research.