An update on thyroid disorders in the postpartum period

PURPOSE

To review the pathophysiology, diagnosis and management of postpartum thyroid dysfunction, and related management of thyroid disorders during lactation.

METHODS

We reviewed the literature on postpartum thyroid dysfunction and management of thyroid disorders during lactation.

RESULTS

The postpartum period is characterized by a rebound from the immunotolerance induced by pregnancy. Routine thyroid function screening is not recommended for asymptomatic women in the postpartum period. Testing thyroid function should be considered at 6-12-week postpartum for high-risk populations, including women with a previous episode of postpartum thyroiditis, Graves' disease, or those with Hashimoto's thyroiditis on thyroid hormone replacement, known thyroid peroxidase antibody positivity, type 1 diabetes mellitus, other nonthyroidal autoimmune disease, or chronic hepatitis C. A serum TSH should also be checked in the setting of postpartum depression or difficulty lactating. If patients have thyrotoxicosis, new-onset or recurrent Graves' disease must be differentiated from postpartum thyroiditis, because the management differs. Periodic thyroid function testing is recommended following recovery from postpartum thyroiditis due to high lifetime risk of developing permanent hypothyroidism. Levothyroxine, and the lowest effective dose of antithyroid drugs, (propylthiouracil, methimazole, and carbimazole) can be safely used in lactating women. The use of radiopharmaceutical scanning is avoided during lactation and radioactive iodine treatment is contraindicated.

CONCLUSIONS

Diagnosing postpartum thyroid dysfunction is challenging, because symptoms may be subtle. A team approach involving primary care providers, endocrinologists, and obstetricians is essential for transitioning thyroid care from the gestational to the postpartum setting.

A case of postpartum thyroiditis following SARS-CoV-2 infection

Postpartum thyroiditis (PPT) is characterized by mild thyrotoxicosis occurring within one year of parturition commonly followed by transient hypothyroidism. Having genetic background of autoimmune thyroid disorders is a risk factor for it because the immune reactivation during postpartum period is a trigger for PPT. Pandemic of COVID-19: caused by SARS-CoV-2 infection is a global health problem, and occurrence of Graves' disease and Hashimoto's thyroiditis after the viral infection have been reported but occurrence of PPT with COVID-19 has never been reported. A 29-year-old woman developed general fatigue four and a half months after parturition, and was diagnosed as having PPT: one month before, she had COVID-19. Hereafter, we define the date of delivery as Day 0 to make timeline clear. SARS-CoV-2 infection was diagnosed by PCR on Day 103, its disappearance from the upper airway confirmed on Day 124, and the thyroiditis diagnosed on Day 136. She had been euthyroid on Day 0 and 95, but thyrotoxic on Day 136. Serum thyroglobulin (Tg) concentration was normal in the presence of anti-Tg antibody, other thyroid-related autoantibodies were negative, and by ultrasonography, the thyroid gland was normal in size and no evidence of increased vascularity. Thyroid function returned to normal by Day 172 without any specific drug therapy. In conclusion, although a clear causal relationship could not be found, we documented the world's first case of PPT developed following COVID-19.

[Thyroid and pregnancy]

During pregnancy thyroid hormones have profound effects on embryonal/fetal development and maternal health. Therefore, thyroid gland disorders should be immediately diagnosed and adequately treated. Pregnancy-specific physiological alterations during pregnancy cause changes in the reference interval for thyroid-stimulating hormone levels and trimester-specific thresholds must be taken into account. This article summarizes the most important diagnostic and therapeutic aspects before, during and after pregnancy. With reference to the period prior to pregnancy, the article discusses iodide supplementation, preconceptional examination of thyroid gland metabolism and the importance of thyroid gland functional disorders for fertility and fulfilling the desire to have children. With a view to the period during pregnancy, the effect of hypothyroxinemia, hypothyroidism, and hyperthyroidism as well as the effects of their treatment on the development of the child are explained. Finally, a description is given of what must be paid attention to in the breast-feeding period and in postpartum thyroiditis.

Assessment of serum thyroid hormone autoantibodies in the first trimester of gestation as predictors of postpartum thyroiditis

Background

Measurement of serum thyroperoxidase autoantibodies (TPOAb) during gestation as a classical marker for the risk of postpartum thyroiditis (PPT) predicts PPT in 1/3 to 1/2 of women. Very few studies have measured serum thyroid hormone Ab (THAb) during gestation, and none as a possible marker for PPT.

Methods

In 412 women who were followed up from 7 to 11 weeks of gestation through 12 months after delivery, we measured THAb (T3.IgM, T3.IgG, T4.IgM, T4.IgG), thyroglobulin autoantibodies (TgAb) and TPOAb at study entry (7–11 week of gestation).

Results

Sixty-three women (15.3%) developed PPT, which progressed to permanent hypothyroidism (PH) in 34/63 (54%). THAb+ve were 21/412 women (5.1%), the frequency being greater in those who then developed PPT (12/63 [19.0%] vs. 9/349 [2.6%], P = 4.6 × 10⁻⁸), and in the PH subgroup (26.5% [9/34] vs. 10.3% [10/29], P = 0.12). THAb positivity occurred in 9/76 women (11.8%) who were TgAb and/or TPOAb+ve compared to 12/336 women who were TgAb and TPOAb negative (3.6%, P = 0.0031). Of these 9 THAb+ve, TgAb and/or TPOAb+ve women, all (100%) developed PPT compared to 3/11 (27.3%, P = 0.0011) THAb+ve, TgAb and/or TPOAb negative women. Of these 9 and 3 PPT women, 8 and 1 progressed to PH (88.9% and 33.3%, respectively, P = 0.12).

Conclusions

Gestational positivity of THAb enhance enormously the predictivity for PPT of gestational positivity of TPOAb/TgAb. However, their low frequency (5.1%) and their sensitivity (17.5% [21/63]) go against their application in lieu of TPOAb/TgAb.

Stable consumption of swordfish favors, whereas stable consumption of oily fish protects from, development of postpartum thyroiditis

PURPOSE

In 236 pregnant women, we showed that selective or predominant consumption of swordfish (group A) was associated with high rates of positivity for serum thyroid autoantibodies (TPOAb and TgAb) throughout day 4 postpartum. In contrast, selective or predominant consumption of oily fish (group B) was associated with TPOAb and TgAb negativity. Rates were intermediate in group C (scanty consumption of swordfish) and group D (consumption of fish other than swordfish and oily fish). Gestational TPOAb positivity is a risk factor for postpartum thyroiditis (PPT), which evolves into permanent hypothyroidism (PH) in about 50% of cases. Purpose of this study was to verify that the different rates of thyroid autoantibodies in the four groups translated into different PPT rates.

METHODS

We expanded our previous cohort (n = 412) and duration of follow-up (month 12 postpartum), and measured frequency of PPT and PH.

RESULTS

At first timester of gestation, we confirmed the different Ab positivity rates in group A vs. group B (TPOAb = 21.7% vs. 4.7%, P < 0.0001; TgAb = 14.1% vs. 2.4%, P < 0.05). Overall, PPT prevalence was 63/412 (15.3%), but 22/92 in group A (23.9%), 4/85 in group B (4.7%; P < 0.0001 vs. group A), 17/108 (15.7%) in group C, and 16/117 (13.7%) in group D. Approximately half of the PPT women had PH, regardless of fish group.

CONCLUSIONS

In conclusion, stable consumption of oily fish (which is enriched in polyunsaturated omega-3 fatty acids) protects from PPT, while stable consumption of swordfish (which is enriched in pollutants) favors PPT. Thus, a dietary prophylaxis of PPT is possible.

Relatively high rate of postpartum thyroiditis in the Straits of Messina area. Predictivity of both postpartum thyroiditis and permanent hypothyroidism by performing, in the first trimester of gestation, thyroid ultrasonography and measurement of serum thyroperoxidase and thyroglobulin autoantibodies

The prevalence of postpartum thyroiditis (PPT) averages 5%, with a range from 1% (Thailand) to 22% (Wales, UK, and Liguria, Italy), but 3.6% in another Italian region (Puglia). Evolution of PPT into permanent hypothyroidism (PH) occurs in approximately 50% of cases. Positive thyroperoxidase autoantibodies (TPOAb) in a pregnant woman is a strong predictor of PPT. Because in previous gestational cohorts we found an approximate 12% rate of TPOAb positivity, which compares with 15% in the Liguria cohort and 6% in the Puglia cohort, we hypothesized that the currently unknown prevalence of PPT in Sicily would approximate the said Liguria prevalence. We also explored the predictive value of serum thyroglobulin Ab (TgAb) positivity and ultrasonographic signs suggestive of thyroiditis (UST) at first trimester of gestation for PPT.

Of 412 pregnant women who were followed-up for 1 year after delivery, 63 (15.3%) developed PPT, and 54% of them had PH. Gestational rates of TPOAb positivity alone, TgAb positivity alone or UST were 11.4%, 7.8% or 35.0%, with associated PPT rates of 66%, 45% or 36%. TgAb assay allowed detection of 9/63 PPT women (14.3%) who were TPOAb-negative. However, TPOAb remained a better predictor compared to TgAb or UST (odds ratio = 32 vs 10 or 13). Lowering the positivity threshold for either Ab to ≥61 U/ml, Ab-positive were 23.8% of PPT women and 17.7% of pH women. UST was detected in 82.5% of women who developed PPT, precisely 88% of those who evolved into PH and 75.9% of those who did not.

Ours is the second study of the new millennium showing a PPT frequency >10%. The dual Ab and lowered threshold strategy correctly predicts more cases of PPT and PH compared to the sole TPOAb strategy. We confirm that half of the PPT women will have PH.

[Thyroid dysfunction in pregnancy. Consensus document. Andalusian Society of Endocrinology and Nutrition (SAEN)]

A position statement on the diagnosis and treatment of thyroid dysfunction in pregnancy has been agreed on behalf of The Sociedad Andaluza de Endocrinología y Nutrición (SAEN), based on a review of the literature to date and all good clinical practice guidelines. The document is set out in different sections as regards the diagnosis and treatment of, overt and subclinical hypo- and hyperthyroidism, isolated hypothyroxinaemia and postpartum thyroiditis. It also justifies the implementation of universal screening for thyroid dysfunction in pregnancy, and provides practitioners who care for these patients with tool for rational decision making.

Development of postpartum Graves' disease and type 1 diabetes after delivery in a patient with gestational diabetes

Pregnancy and the postpartum period are associated with changes of the immune system. These changes might eventually result in autoimmune diseases, such as Graves’ disease and type 1 diabetes mellitus, in the postpartum period. We describe a case of a patient with gestational diabetes who developed both Graves’ disease and type 1 diabetes mellitus in the postpartum period. The pathology of gestational diabetes (GDM) is close to that of type 2 diabetes mellitus. However, the present case emphasizes the importance of screening and monitoring high‐risk GDM patients for all available autoimmune antibodies throughout pregnancy and the postpartum period, as GDM has a risk of developing into type 1 diabetes and multiple autoimmune diseases. In addition, only Graves’ disease was transient, whereas type 1 diabetes mellitus remained permanent in the present case. Thus, the present case shows etiological differences between these two autoimmune diseases. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2010.00089.x,2011)