While the link between clinical thyroid dysfunction and postpartum psychosis (PP) has been established, researchers are uncertain whether clinical thyroid dysfunction is a biological response to psychosis (with or without postpartum onset) or an expected outcome related to the delivery of a child. This 2021 study at the Central Institute of Psychiatry in Jharkhand, India, compared the thyroid function of those with psychosis with postpartum onset (PPO), psychosis without postpartum onset (PWPO), and normal postpartum female controls (HC). The authors hoped the examination of thyroid function amongst the three different groups would provide information that might assist in effectively predicting and treating PP.
The study sample consisted of 20 women from each group (PPO, PWPO, and HC), for a total of 60 participants. Women were eligible for the PPO group if they were between the ages of eighteen to forty and were diagnosed with psychosis onset within six months of delivery (according to a hospital-based diagnostic code called the ICD-10 DCR criteria). Women were eligible for the PWPO group if they had been diagnosed with psychosis at any time in their life outside of the postpartum period according to that same diagnostic code. Finally, women were eligible for the HC group if, within the six-month postpartum period, they scored low on a scale that measured psychological stress (called the GHQ 12). Women were deemed ineligible for the study if they had a history of thyroid abnormality or alteration including the complete or total removal of the thyroid, a family history of thyroid disorders, a history of neurological disorders, or exposure to certain drugs that could affect their thyroid functioning. All women were similar in sociodemographic information including age, sex, ethnicity, education, and employment status.
Over the course of the study, the subjects’ thyroid function was measured using biochemistry and ultrasound methods. The study determined the volume of each participant’s thyroid. It also tested for levels of various indicators of the thyroid’s effectiveness at regulating growth and energy levels. These indicators included: thyroid-stimulating hormones (TSH), free thyroxine (FT4), and free triiodothyronine (FT3). Participants were also surveyed to assess any psychiatric symptoms they may have been experiencing. Several of the scales administered in the interview include: the Comprehensive Psychopathological Rating Scale (CPRS), which measures and rates the severity of psychiatric symptoms, and the Hamilton Depression Rating Scale (HDRS), widely used to assess clinical depression.
Once accounting for possible differences in the groups, the study found that PPO patients reported that they experienced more psychiatric symptoms than the participants from either of the other two groups. In terms of the physical differences between the thyroid glands of the three groups, the PPO group was found to have greater total thyroid volume, right lobe volume, and right lobe length, breadth, and height in comparison to the PWPO group. Additionally, the HC group was found to have a greater left lobe thyroid length than the PWPO group. An increase in thyroid growth is known to affect the production of thyroid hormones, either causing an increase or decrease in their production.
While there was no significant difference in the TSH and FT3 levels of the three groups, FT4 levels (a hormone produced by the thyroid that indicates how efficiently the thyroid gland works in the body) were significantly higher in the PPO group than the HC group. Possible explanations for the FT4 elevation include the body’s redistribution of T4 (thyroxine that is attached to protein in the blood), temporary resistance to T4 in the pituitary thyrotroph, and an increase in difficulty clearing T4. Additionally, the differences in thyroid measurements between the three groups could be attributed to physiological changes during pregnancy, for example, an increase in body mass. While the right thyroid lobe is more likely to increase due to a variety of health conditions, differences in right lobe volume across the groups in the study (largest among the PPO group) suggest the right lobe of the thyroid may be the most specific in finding that seems to indicate postpartum psychosis.
The study is limited because of its small sample size, but its findings are meaningful in that the researchers have identified several additional potential biomarkers for PP: increased in FT4 hormone and right thyroid lobe volume. Future research will be necessary to clarify the thyroid’s role as a biomarker for PP.
Written by Hannah Dineen, Clinical Research Intern
Sethy RR, Garg S, Ram D, Tikka SK. Thyroid function in postpartum psychosis: An exploratory study. Asia Pac Psychiatry. 2021;13:e12465. https://doi.org/10.1111/appy.12465