|Year : 2022 | Volume
| Issue : 3 | Page : 165-167
Universal thyroid screening in maternal health care in India: The need of the hour
Santosh Kumar Singh1, Sanchita Chakrabarti2, AK Naik3, Barun Kumar Chakrabarty4, N Nagaraja5, Vimal Upreti6
1 Department of Medicine, CH (NC), Udampur, Jammu and Kashmir, India
2 Department of Political Science, Hooghly Women's College, Burdwan University, West Bengal, India
3 Department of Hospital Administration, AFMC, Pune, Maharashtra, India
4 Department of Pathology, 151 Base Hospital, Guwahati, Assam, India
5 Department of Gynecology and Obstetrics, CH (SC), Pune, Maharastra, India
6 Department of Endocrinology, AH (R&R), New Delhi, India
|Date of Submission||12-Dec-2020|
|Date of Decision||19-Dec-2020|
|Date of Acceptance||04-Feb-2021|
|Date of Web Publication||01-Apr-2022|
Lt Col (Dr) Barun Kumar Chakrabarty
Classified Spl (Path), Department of Pathology, 151 Base Hospital, Guwahati, Assam
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Singh SK, Chakrabarti S, Naik A K, Chakrabarty BK, Nagaraja N, Upreti V. Universal thyroid screening in maternal health care in India: The need of the hour. J Mar Med Soc 2022;24, Suppl S1:165-7
|How to cite this URL:|
Singh SK, Chakrabarti S, Naik A K, Chakrabarty BK, Nagaraja N, Upreti V. Universal thyroid screening in maternal health care in India: The need of the hour. J Mar Med Soc [serial online] 2022 [cited 2022 Nov 27];24, Suppl S1:165-7. Available from: https://www.marinemedicalsociety.in/text.asp?2022/24/3/165/342379
Several studies in the last two decades demonstrated adverse effects of thyroid dysfunction during pregnancy on the mother and the developing child. On the other side, there is tremendous advancement and expansion of facilities in the field of diagnostic medical services which resulted in the precise establishment of a trimester, method, and ethnicity-specific reference range for maternal thyroid function tests by several epidemiological studies. These changes in the understanding of the maternal thyroid physiology and its adverse long-term impact on socioeconomy of the country have led to a debate among various regulatory bodies, social scientists, scientific communities, and national policy formulators on the introduction of universal thyroid screening instead of high-risked case-based approach as a part of regular antenatal checkup.
At present, India is considered iodine sufficient though several new studies are emerging questioning the iodine status, particularly for the vulnerable population like pregnant and lactating mothers. Prevalence of hypothyroidism during pregnancy in India reported ranging from 4.8% to 13%. Recent research showed maternal thyroid dysfunction, either hyper or hypothyroidism leads to various detrimental outcomes in the mother and offspring.
The National Health Mission (NHM) was launched in 2013 to achieve the goals and objectives on India's flagship health program National Rural Health Mission. National surveys demanded further articulation of the strategic approach rather than several vertical approaches leading to the introduction of RMNCH + A under NHM. The launching of National Guidelines for Screening of Hypothyroidism during Pregnancy under the flagship of RMNCH + A is an important step in that direction. The available national programs for the prevention and treatment of thyroid diseases are National Guidelines for Screening of Hypothyroidism during Pregnancy and National Iodine Deficiency Disorders Control Programme. As per program recommendation with an intake of 10 g of iodized salt which contains 150 mcg of iodine, physiological requirements are meeting sufficiently in normal conditions. ATA 2017 guideline and the WHO recommend 250 μg daily iodine intakes for pregnant and lactating women.
There is no universal consensus amongst varoius policy enforcing bodies for universal screening of maternal thyroid disorders during pregnancy period. In 2017, ATA reiterated the proposals of 2011 mentioning the inability to provide recommendations, as there is insufficient evidence for or against universal screening with several riders to select the high-risk group. The American College of Obstetricians and Gynecologists, Society of Maternal-Fetal Medicine, American Association of Clinical Endocrinologists, and Cochrane Collaboration are authorities which are supporting for high-risk selective screening instead of universal screening. The European Thyroid Association in their 2014 guidelines recommended aggressive case finding high-risk-targeted approach, but they took note that the practice of universal screening is going to help to detect the large undetected hypothyroid pregnant population and improve the pregnancy outcome with treatment. However, the Spanish Society of Endocrinology and Nutrition and Indian Thyroid Society (ITS) recommended universal maternal thyroid-stimulating hormone (TSH) screening. Recently, various researchers such as Stagnaro-Green A also published their research highlighting the advantages of universal screening. Though there is lack of consensus among various regulatory bodies, but on ground surveys conducted among European and American practitioners showed that many of them had already practised routine TSH testing in pregnant women. If we analyze all the risk factors in the perspective of the entire Indian population of childbearing age women, a significant percentage of them will be considered as at high risk which will be further increased if we assess with ATA 2017 guideline criteria which are more stringent and aggressive; therefore, universal screening is ideal.
TSH screening for thyroid disorder in pregnancy fits with the characteristics of active screening as thyroid disorder is highly prevalent in pregnant women; TSH measurement is simple, precise, accurate, and cheap; and if the disorder is detected in time, it may be treated safely with clinically detectable favorable outcome depicting clear cost–benefit ratio. The study of thyroid disorder requires a single blood sample collection which can be easily compiled with the other regular tests performed during pregnancy.
The ultimate goal of universal screening of maternal TSH level is the diagnosis of dysfunction at the prenatal or early gestational stage so that therapeutic intervention can be done before crucial irreversible stages of fetal development. Studies were performed to evaluate the cost-effectiveness of universal screening demonstrated favorable outcomes. Universal TSH screening would help to diagnose and treat women with autoimmune subclinical hypothyroidism (SCH). It would also help in close monitoring of euthyroid antithyroid antibody-positive women, who may develop hypothyroidism or postpartum thyroiditis.
The screening should be done in such a manner that intervention can be done within the time-based therapeutic window to get the optimum benefit. It has been shown that 6–10 weeks delay of levothyroxine therapy in early pregnancy increases the probability of neurodevelopmental anomaly of the offspring. Therefore, the screening period should be in the early pregnancy period preferably within 1st trimester. Trimester-specific reference ranges maternal serum TSH testing is a reasonably economical, widely available, and reliable test. Endocrine Society guidelines recommend the free T4 index along with TSH rather than free T4 assays during pregnancy. None of the guidelines recommend universal thyroid peroxidase (TPO) antibody screening or treatment of euthyroid antithyroid antibody-positive women.
There is a general consensus among clinical scientists regarding pregestational hypothyroidism treatment goal preconception TSH target level. However, the paradox of the same is while the screening program treatment requirement target was set at the same level it was not agreed upon. The knowledge of positive thyroid antibody status is helpful as it is considered as criteria for high-risk pregnancy. With the severity of clinical consequences and the present prevalence rate, a universal screening program would be justified for identifying women with overt hypothyroidism.
Anemia, especially iron deficiency anemia, affects about 60% of pregnant mothers with hypothyroidism. In an iron-deficient patient with the presence of concomitant iron deficiency, the iron salt treatment is found to be ineffective without a levothyroxine supplement. Therefore, the high prevalence of iron deficiency and its effects on mother and fetus also warrants universal thyroid screening in countries like India.
With the advent of medical science, improvement in economic conditions, increase in educational level, small family norm adaptation, and political consciousness, there is a “felt demand” appreciated in the society regarding the best level of care for pregnant mothers with all possible amenities available. Therefore, the need for universal screening of thyroid disorders in pregnancy and its aftermath are not only limited to the research activities within scientific communities but debated in social forums generating social demand.
There is clear cut evidence of multiple adverse outcomes of overt hypothyroidism on the feto-maternal unit. However, the effects of SCH and antithyroid antibodies are controversial. The major disagreement against universal screening is due to a lack of evidence on the treatment benefit of SCH. The clinical entity of isolated maternal hypothyroxinemia is not being accepted as an independent thyroid disease and its pathologic significance is under review. Thus, the ATA 2017 guidelines do not recommend routine screening or treatment and Endocrine Society 2012 guidelines do not mention for isolated hypothyroxinemia in pregnancy.
Studies demonstrated contradictory evidence for the association between thyroid autoimmunity and maternal pregnancy-related complications with mostly exhibiting positive association. Gestational hyperthyroidism may be associated with hyperemesis gravidarum but most of the time, it disappears spontaneously without treatment. Moreover, as the fetus is protected from excess FT4 by the counter effect of placental type 3 deiodinase, untreated subclinical hyperthyroidism does not have adverse maternal or fetal outcomes unlike hypothyroidism. Universal screening can result in overtreatment in this group of pregnant mothers resulting in serious clinical implications.
One of the most significant changes in the 2017 ATA guidelines is the recommendation on the defining criteria of a pregnancy-specific TSH reference range. In India, in our national guideline, the previous recommendation was adopted and the management plan was formulated in absence of any established national reference range. However afterward, in subsequent studies, many centers across the world reported that using these fixed cutoffs led to false high reporting of hyperthyrotropinemia (7.4%–27.8%). Therefore, there is an urgent need for the rectification of defining criteria of TSH level as well as a treatment protocol.
2017 ATA guideline changed their position and now recommended that in cases of TPO Ab positivity, levothyroxine therapy can be considered for pregnant women with TSH concentrations >2.5 mIU/L. ITS clearly recommends four specific high-risk groups of pregnant mothers for screening with anti-TPO antibodies. In our national guideline for sample analysis, different methods are mentioned (chemiluminescence assay/auto-analyzer/semi auto-analyzer) without clarification on assay-specific variations. Therefore, more clarifications are needed in the program vendetta.
In summary, in the factual analysis, it is evident that in a country like India, national universal TSH screening for the entire pregnant population is the need of the hour rather than a targeted high-risk approach. This argument is validated based on the high prevalence of thyroid disorders, the continued prevalence of iodine deficiency, the impact of iron deficiency, serious socioeconomic adverse effects of the disorder, and cost-effectiveness of the program.
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