AbnormalTHYROID During Pregnancy Dr.Elwassiela Salih MD

What is thyroid disease? Thyroid disease is a disorder that results when the thyroid gland produces more or less thyroid hormone than the body needs Divided into two: -hyperthyroidism -hypothyroidism

How does pregnancy normally affect thyroid function? Two pregnancy-related hormones—(hCG) and estrogen—cause increased thyroid hormone levels in the blood. Made by the placenta, hCG is similar to TSH and mildly stimulates the thyroid to produce more thyroid hormone.

Increased estrogen produces higher levels of thyroid-binding globulin, a protein that transports thyroid hormone in the blood. These normal hormonal changes can sometimes make thyroid function tests during pregnancy difficult to interpret.

1st trimester, the fetus depends on the mother’s supply of thyroid hormone, which it gets through the placenta. At 10 to 12 weeks, the baby’s thyroid begins to function on its own. The baby gets its supply of iodine, which the thyroid gland uses to make thyroid hormone, through the mother’s diet.

Women need more iodine when they are pregnant—about 250 micrograms (μg) a day Thyroid gland enlarges slightly in healthy women during pregnancy- enough to be detected by u/s . Higher levels of thyroid hormone in the blood, increased thyroid size, and other symptoms common to both pregnancy and thyroid disorders.

HYPerthyroidism Usually caused by Graves’ disease and occurs in 1:500 pregnancies In Graves’ disease, the immune system makes an antibody called thyroid stimulating immunoglobulin which mimics TSH and causes the thyroid to make too much thyroid hormone.

A woman with preexisting Graves’ disease usually improves in 2nd and 3rd trimester. It usually worsens again in the first few months after delivery.

How does hyperthyroidism affect the mother and baby? Uncontrolled hyperthyroidism during pregnancy can lead to -congestive heart failure -preeclampsia—a dangerous rise in blood pressure in late pregnancy -thyroid storm—a sudden, severe worsening of symptoms

-Diarrhoea -Vomiting -Abdominal pain -Psychosis -Cardiac arrhytmias including atrial fibrillation -Diarrhoea -Vomiting -Abdominal pain -Psychosis

- thyroid stimulating h - thyroid stimulating h. may cross the placenta and cause fetal thyrotoxicosis and goitre

Main complications for baby: -fetal growth restriction -stillbirth -fetal tachycardia -premature delivery -miscarriage

diagnosis Some symptoms are common features in early pregnancies, including mild maternal tachycardia, heat intolerance, fatigue, weight loss and heart murmur Other more indicative symptoms: rapid and irregular heartbeat, a fine tremor, unexplained weight loss or failure to have normal pregnancy weight gain, and the severe nausea and vomiting Confirmed by high level of T4 and T3, with reduced level of TSH

Treatment Mild hyperthyroidism in which TSH is low but free T4 is normal does not require treatment Propylthiouracil (PTU) or sometimes methimazole- use lowest dose as it cross placenta Beta-blockers may be indicated initially before antithyroid drugs take effects Radioactive iodines-contraindicated because it completely obliterates fetal thyroid gland Rarely, surgical used

Hypothyroidism Causes: -iodine deficiency - Hashimoto’s thyroiditis -atrophic thyroiditis - congenital absence of thyroid - inadequately treated existing hypothyroidism - treated hyperthyroidism : surgery, radioiodine or drugs(amiodarone,lithium,iodine,antithyroid drugs)

How does hypothyroidism affect the mother and baby? Some of the same problems caused by hyperthyroidism can occur in hypothyroidism. Uncontrolled hypothyroidism during pregnancy can lead to -congestive heart failure -pre-eclampsia -anemia -miscarriage -low birthweight -stillbirth -cognitive and developmental disabilities in the baby

Diagnose? High levels of TSH and low levels of free T4 Symptoms of hypothyroidism in pregnancy include -extreme fatigue -cold intolerance -muscle cramps -constipation -problems with memory or concentration. 

treatment Synthetic thyroxine-identical to the T4 made by the thyroid gland Women with pre-existing hypothyroidism will need to increase their prepregnancy dose of thyroxine Thyroid function should be checked every 6 to 8 weeks during pregnancy If the dx is made in px, in the absence of cardiac ds, consider a starting dose of 100 μg daily. In practice, aim for a TSH level <2.5mu/l Thyroxine can be safely taken during breast-feeding.

treatment Based on symptoms and not biochemical results Most recover spontaneously Hyperthyroid phase: Beta-blockers Hypothyroid phase: thyroxine – treatment should be withdrawn after 6 months to check for recovery Long term follow up should be with annual TFT

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