Rate of hypothyroidism higher in adults after schizophrenia diagnosis
A cohort of adults with schizophrenia in Israel had a higher rate of hypothyroidism after diagnosis than controls without schizophrenia, although no difference was found before diagnosis between the two groups, according to study data.
“There is no significant alternation in thyroid functions in patients suffering from schizophrenia before diagnosis,” Joseph Meyerovitch, MD, professor at the Sackler School of Medicine, Tel Aviv University, and attending physician at the Institute for Endocrinology and Diabetes, Schneider Children's Medical Center of Israel, told Healio. “After diagnosis of schizophrenia and initiation of antipsychotic treatment, the rate of hypothyroidism was significantly higher in the schizophrenic patients.”
In a study published in Psychiatry Research, Meyerovitch and colleagues conducted a retrospective study of 1,252 adults with schizophrenia who were aged 18 to 64 years at diagnosis, and 3,576 controls selected from the Clalit Health Services database in Israel from 2002 to 2015. Demographics, height, weight, chronic medical diagnoses, laboratory data and annual drug prescriptions issued were recorded. All participants in the schizophrenia group had a diagnosis in their electronic health records, and individuals were considered to have hypothyroidism if there was a diagnosis in their health records or if they had at least two annual replacement prescriptions for levothyroxine. Researchers compared the rates of hypothyroidism in the schizophrenia group before and after diagnosis and with the control group.
Before diagnosis, 2.3% of participants in the schizophrenia group had hypothyroidism, similar to the 2.4% hypothyroidism rate in the control group. After a mean follow-up period of 4.3 years after diagnosis, the schizophrenia group had a hypothyroidism rate of 9.7%, higher than the 5.1% rate found in the control group (P < .001).
Hypothyroidism rates did not change after stratification according to lithium prescription. There was no significant difference found between the schizophrenia and control groups in the number of participants with antithyroid peroxidase antibodies or antithyroglobulin antibodies.
“Our study provides several important insights into the potential association between schizophrenia and hypothyroidism,” the researchers wrote. “Our finding of a higher rate of hypothyroidism only after the diagnosis of schizophrenia and initiation of treatment, and the different characteristics of the hypothyroid patients with and without schizophrenia, suggest that hypothyroidism may have a different cause in patients with schizophrenia, either disease- or treatment-related, compared to hypothyroidism in the general population.”
Meyerovitch said the findings reveal the importance of screening for thyroid disorders in individuals with schizophrenia who are undergoing antipsychotic treatment.
“We need to assess the clinical response of the mental status to the treatment of hypothyroidism of patients suffering from schizophrenia,” Meyerovitch said about future research.
For more information
Joseph Meyerovitch, MD, can be reached at firstname.lastname@example.org.