Isolated Maternal Hypothyroxinemia May be Associated with Insulin Requirement in Gestational Diabetes Mellitus.

An insulin regimen may be necessary for about 30% of the patients with gestational diabetes mellitus (GDM). We aimed to investigate the association of free T4(fT4) levels with insulin requirement in pregnant women with GDM. We included pregnant women whose TSH levels were within the normal range and who were diagnosed with GDM, and excluded patients with thyroid dysfunction, chronic illnesses, or any previous history of antithyroid medication, levothyroxine, or antidiabetic medication use. The diagnosis and treatment of GDM were based on American Diabetes Association guidelines. Demographic features, previous history of GDM and gestational hypertension were recorded. Baseline (at diagnosis of GDM) fasting blood glucose, HbA1c, TSH, fT4, and fT3 levels were analyzed. We grouped the patients according to their baseline fT4 levels: isolated maternal hypothyroxinemia (IMH) (group A) vs. in the normal range (group B). We grouped those also based on insulin requirement in 3rd trimester. Of the patients (n=223), insulin requirement was present in 56, and IMH in 11. Insulin requirement was more frequent in group A than in group B (p=0,003). HbA1c (≥47,5 mmol/mol) and fT4 level (lower than normal range) were positive predictors for insulin requirement (OR:35,35, p=0,001; and OR:6,05, p=0,008; respectively). We showed that IMH was closely associated with insulin requirement in GDM. Pregnant women with IMH and GDM should be closely observed as regards to glycemic control. If supported by future large studies, levothyroxine treatment might be questioned as an indication for patients with GDM and IMH.

Differences in Clinical Aspects Between Subacute Thyroiditis Associated with COVID-19 Vaccines and Classical Subacute Thyroiditis.

Subacute thyroiditis (SAT) developed after SARS-CoV-2 vaccines has been less studied. We aimed to compare classical SAT and SAT developed after SARS-CoV-2 vaccines in the context of clinical aspects. Adults with SAT detected in 90 days of COVID-19 vaccination (CoronaVac or Pfizer/BioNTech) were grouped as Vac-SAT. Those with a history of SARS-CoV-2 or upper respiratory tract infection in 6 months before the vaccination, or vaccination with another antiviral vaccine after COVID-19 vaccination were excluded. Those with SAT detected before COVID-19 pandemic were grouped as Classical-SAT. Of total (n=85), female/male (54/31) ratio and age [43 (23-65)] were similar in Vac-SAT (n=23) and Classical-SAT (n=62). Duration between vaccine and SAT was 45 (7-90) days, and similar in CoronaVac-SAT (n=5) and BioNTech-SAT (n=18). SAT-duration was 28 (10-150) days, and higher in Vac-SAT than in Classical-SAT (p=0.023). SAT was developed after the 1st dose vaccine in minority in CoronaVac-SAT (n=2) and BioNTech-SAT (n=3) (p=0.263). Previous LT4 use, and TSH elevation after resolution were more frequent in Vac-SAT than in Classical-SAT (p=0.027 and p=0.041). We included a considerable number of patients with SAT occurred after COVID-19 vaccines. We cannot provide clear evidence regarding the association of COVID-19 vaccines with SAT. SAT associated with CoronaVac or BioNTech seems unlikely to be occurred after the 1st dose, and to have a longer duration, more likely to be associated with previous LT4 use and lead TSH elevation after resolution than Classical-SAT. TSH should be followed-up after the resolution of SAT detected after COVID-19 vaccination.