A clinical study to determine the prevalence of thyroid disease in association with iron deficiency and diabetes among Tasmanian pregnant women

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Current practice at LGH and generally in Tasmania is selective case based antenatal testing for thyroid disease. This is often conducted in a very ad hoc manner and the actual current incidence and prevalence of thyroid disease within the pregnant population is not yet known. Many professional bodies advocate testing for thyroid dysfunction in pregnancy only if symptoms exist, in the setting of prior personal or family history or in the presence of an antecedent or associated medical condition. Iron deficiency has been shown to have a negative impact on maternal thyroid function, which is compounded in areas of borderline iodine deficiency. Serum ferritin, transferrin receptor and body iron stores all significant predictors of TSH. A joint statement by the American Thyroid Association, the American Association of Clinical Endocrinologists and the Endocrine Society in 2005 made firm recommendations for universal screening for thyroid dysfunction in pregnancy as soon as pregnancy is diagnosed.5 Guidelines on management of thyroid disorders during pregnancy published by LeBeau et al in 2006 is in further support of this. The trial will be offered to pregnant women during their attendance at the antenatl clinic at the LGH. The midwives will assist in the study by conducting the questionnaire and organizing blood tests and consenting participants during the booked visits. Obstetric, medical, family, social history along with demographic, and perinatal information would entered into the Obstetrix Database as per routine. A further questionnaire addressing detailed thyroid history will be administered. The questions have been derived and modified from Abalovich et al and their recommended approach for case finding. Recruits will then be referred to the Pathology service at the LGH to have their blood and urine taken. Each recruit should have phlebotomy at the same time each day, i.e 8-10 am to eliminate diurnal variations. Fasting serum/plasma collected would be tested for TSH, FT4, FT3, TPO antibodies, FBC, Fe studies also by the Launceston General Hospital pathology service when usually present for 26 weeks Oral Glucose Tolerance Test (OGTT). TSH, FT3, FT4 & Ferritin (part of Fe studies) to be assayed using Ortho Clinical Diagnostics ECI. The Beckman Coulter LH500 analyzer to be used for the FBC, and iron studies to be performed using an Abbott C8000 analyzer. Remaining serum will be divided into 5 aliquots of 1-2ml each and stored frozen at -70 degree for future reference. Furthermore, we assessed of the utility of HbA1c when used as a screening tool in pregnancy. A direct comparison of HbA1c levels with results of the OGTT test in targeted gravid women, tested concurrently at the 24-28 gestational week and was undertaken in a subset of 480 pregnant women. This amendment was approved the Ethics committee. An informed consent was obtained from all women.