Hypothyroidism in pregnancy

[diogenes]

This paper examines the relationships between TSH and FT4 as diagnostics in pregnancy (behind a paywall ). No FT3 done.

Hypothyroid symptoms throughout pregnancy are predominantly associated with thyroxine and not with thyrotropin concentrations       

 August 2022 

Thyroid        

DOI: 10.1089/thy.2022.0244

 Victor J.M. Pop, Lianne Hulsbosch Myrthe, GBM Boekhorst , Wilmar M Wiersinga et al

Hypothyroid symptoms throughout pregnancy are predominantly associated with thyroxine and not with thyrotropin concentrations        

 Background: It is unclear whether levels of hypothyroid symptoms in pregnant women with (sub)clinical thyroid dysfunction differ from euthyroid controls and whether FT4/TSH changes throughout pregnancy affect hypothyroid symptom levels. The objective was twofold: 1) To compare hypothyroid symptom levels between thyroid dysfunction subgroups and a carefully defined reference group; 2) to assess the association between FT4/TSH changes throughout pregnancy and hypothyroid symptom levels adjusted for depressive symptoms.

Methods: The current study was a longitudinal prospective cohort study in 1800 healthy pregnant women. At each trimester of pregnancy, hypothyroid symptoms were assessed with a 12-item symptom hypothyroidism checklist and depressive symptoms with the Edinburgh Depression Scale. Thyroid dysfunction was defined using the 2.5th-97.5th FT4/TSH percentile of TPO-Ab negative women. Euthyroid controls consisted of women with appropriate FT4 levels within the 10-90th percentile and with a normal TSH level. Hypothyroid mean symptom scores were compared between controls and several thyroid dysfunction subgroups. Growth mixture modeling was performed to evaluate possible longitudinal trajectories of hypothyroid and depressive symptoms. The association between hypothyroid symptom trajectories (adjusted for depression) and FT4/TSH changes was assessed with multivariate logistic regression analysis. Results: Women with overt hypothyroidism (FT497.5th) and hypothyroxinemia (FT497.5th), because 82% of these SCH women had FT4 levels in the euthyroid range. Two groups of hypothyroid and depressive symptoms were defined: a persistently low and persistently high symptom group. FT4 decreased in 98% of the women from the first to third trimester and per unit pmol/L FT4 decrease (not TSH increase), the likelihood to present persistently high hypothyroid symptoms increased with 46%, adjusted for depression.

Conclusion: A properly defined euthyroid control group distinguishes women with hypothyroid symptoms. A FT4 decrease towards end-term is associated with persistently high hypothyroid symptom levels. Clinicians should be aware of the importance of FT4 stratification in SCH women. 

[radd]

diogenes,

Thank you for posting.

[tattybogle]

"...and per unit pmol/L FT4 decrease (not TSH increase), the likelihood to present persistently high hypothyroid symptoms increased ..."

more proof that " TSH isn't all its cracked up to be" and that actual hormone levels should be given more weight in treatment decisions .

Finding it a bit difficult to get my head round exactly who they tested and definitions of sub groups etc from the summary .... but i think i get the gist .