Thyroid disease in Pregnancy

Thyroid disease in pregnancy

Dr. Hem Nath Subedi, ResidentOBGYN

COMS TH , BHARATPUR, NEPAL

Objectives

• To explain anatomic structure and physiologic function of the gland.

• To explain role of thyroid hormone in Pregnancy

• To Explain disease entity of thyroid in pregnant woman.

• To give knowledge to participants about clinical features and management regarding thyroid disease.

Contents

• Anatomy • Physiology• Changes in thyroid physiology in pregnancy • Hyperthyroidism in pregnancy• Hypothyroidism in pregnancy • Management • Screening in pregnant women• Postpartum thyroiditis• Thyroid nodules and pregnancy

Anatomy

• The thyroid gland is anterior in the neck below and lateral to the thyroid cartilage.

• It consists of– Two lateral lobes – Isthmus

Richard F .Thyroid anatomy In GRAY’S Anatomy, third edition , Elseveir, uk , 2015

Histology

Kim E. Thyroid Physiology In Ganong’ Review of Medica Physiology, 24th edition, New York, Mac Graw Hill , 2012.

Physiology


Iodine Metabolism


Thyroid hormone biosynthesis


Thyroid hormone in circulation


Regulation of thyroid hormone secretion


Changes in Pregnancy

• Physiological changes of pregnancy cause the thyroid gland to increase production of thyroid hormones by 40 to 100 percent to meet maternal and fetal needs.

• mean thyroid volume increased from 12 mL in the first trimester to 15 mL at delivery pregnancy-induced changes.

• TRH levels are not increased during normal pregnancy.• Due to beta-hcg, initially TSH level decrease in

pregnancy, which give false report of subclinical hypothyroidism.

Cunninghams . Endocrine disorders: In Williams Obstetrics, 24th Edition, New York, Mac Graw Hill , 2014 pp 1147.

Hyperthyroidism

• Hyperthyroidism affects 0.2 % of pregnant women and 95% of these will have diagnosis of Grave’s disease .

• The incidence of thyrotoxicosis or hyperthyroidism in pregnancy is varied and complicates between 2 and 17 per 1000 births when gestational-age appropriate TSH threshold values are used.

• In Nepal incidence of hyperthyroidism is 1.59%.

Graves disease

• Graves' disease, also known as toxic diffuse goiter is an autoimmune disease that affects the thyroid.

• A long-acting thyroid stimulator (LATS), distinct from pituitary thyrotropin (TSH), is found in the serum of some patients with Graves' disease.

• Graves' hyperthyroidism was found to contain a long-acting thyroid stimulator (LATS)

https://en.wikipedia.org/wiki/Autoimmune_disease

Incidence


Possible causes of hyperthyroidism• Graves Disease• Toxic Multinodular Goiter• Toxic nodule/adenoma • Subacute thyroiditis• Acute thyroiditis• Iordine treatment• Amiodarone therapy• Lithum therapy• Hyperfunctioning ovarian teratoma• TSH producing adenoma• hCG producing tumor• Thyroid carcinoma James, Steer, Weiner.Thyroid disease: in High risk pregnancy management option, fourth

edition, uk , elsevier, 2006 pp 813-829.

Clinical features

• Suggestive findings include tachycardia that exceeds that usually seen with normal pregnancy, thyromegaly, exophthalmos, and failure to gain weight despite adequate food intake.

• Diagnosing hyperthyroidism in early pregnancy may be difficult.

• Some time associated with Hyperemesis.James, Steer, Weiner.Thyroid disease: in High risk pregnancy management option, fourth edition, uk , elsevier, 2006 pp 813-829.

Maternal effect

• Prepregnacy – Infertility

• 1st trimester – Miscarriage – Hyperemesis

• Second and third trimester – Heart failure– Preeclampsia – Adverse perinatal outcome- perinatal mortality rate is 6-

12%.(IUGR, placental abruption, still birth)James, Steer, Weiner.Thyroid disease: in High risk pregnancy management option, fourth edition, uk , elsevier, 2006 pp 813-829.

Fetal Effects

• Fetal thyrotoxicosis ( Goitorous)• Nonimmune hydrops • Goitrous hypothyroidism• Nongoitrous hypothyroidism

Fetal effect


Diagnosis • Thyrotoxicosis usually presents in the late first or early

second trimester.• Symptoms are as for thyrotoxicosis outside pregnancy, but

these may be unhelpful and commonly reported by many euthyroid pregnant women (e.g., palmar erythema, emotional lability, vomiting, goiter. and heat intolerance).

• Discriminatory symptoms may be weight loss, tremor, lid lag, lid retraction. and a persistent tachycardia greater than 100 beats/min.

• Diagnosing hyperthyroidism in early pregnancy may be difficult.

• The diagnosis of hyperthyroidism is confirmed by an elevated free T4 and/or free T3 with suppressed TSH levels.Cunninghams . Endocrine disorders: In Williams Obstetrics, 24th Edition, New York, Mac

Graw Hill , 2014 pp 1147.

Therapeutic modalities for hyperthyroidism can be divided into five categories

• Thionamides (propylthiouracil, carbimazole, methimazole)- Prevent conversion of T4 to T3 and reduces the peroxidase function and block coupling of the idotyrosine.

• β-Blockers-Decrease palpitation as well as reduces the peripheral conversion of T4 to T3.

• Iodides• Radioactive iodoine• Surgery.

James, Steer, Weiner.Thyroid disease: in High risk pregnancy management option, fourth edition, uk , elsevier, 2006 pp 813-829.

Management


Management contd….


Thyroid Storm and Heart Failure

• Both are acute and life-threatening in pregnancy.

• Thyroid storm is a hypermetabolic state and is rare in pregnancy.

• In these women, cardiomyopathy is characte rized by a high-output state, which may lead to a dilated cardiomyopathy.

• Heart failure develops in 8% of the patient with uncontrolled hyperthyroidism.Cunninghams . Endocrine disorders: In Williams Obstetrics, 24th Edition, New York, Mac

Graw Hill , 2014 pp 1147.

Thyroid Storm management Protocol


Hypothyroidism

• Hypothyroidism affects 1% of pregnant women, and as with hyperthyroidism, many of the symptoms are encountered in normal pregnancy.

• 2 and 10 pregnancies per 1000.• Incidence in nepal is 2.26%

Causes

• Autoimmune (hashimoto thyroiditis)• Iatragenic (lithium, amiodarone )• Transient(de Quervain’s thyroiditis or

postpartum thyroiditis)


Clinical features

• Fatigue• Constipation• Cold intolerance• Muscle cramps• Weight gain


Diagnosis

• Hypothyroidism may be diagnosed in those with a reduced free T4 concentration in association with an elevated TSH, which outside pregnancy, is a sensitive indicator of the degree of thyroid hormone deficiency.

• Identifying TPO autoantibodies can confirm the diagnosis, but these are nonspecific, being present in 20% to 30% of the normal population.


Maternal effect • Myxoedema coma -extremely rare in

pregnancy, but it represents a true medical emergency with a 20% mortality rate.

• The clinical picture of myxedema coma includes hypothermia, bradycardia, decreased deep tendon reflexes, and altered consciousness.

• Hyponatremia, hypoglycemia, hypoxia, and hypercapnia may also be present.


Maternal effect


Fetal effect

• Low IQ Level • Crentinism • Neonatal or fetal

hypothyroidism• Congenital absence of the

thyroid gland


Management


Subclinical hypothyroidism

• If normal thyroid hormone level but elevated TSH level.

• This thyroid condition is common in women, but its incidence can be variable depending on age, race, dietary iodine intake, and serum TSH thresholds used to establish the diagnosis.

• its prevalence in pregnancy has been estimated to be between 2 and 5 percent.

• 17% of subclinical hypothyroid women will develop hypothyroidism in next 20 years.


Subclinical Hypothyroidism and Pregnancy


TSH Level Screening in Pregnancy• The American College of Obstetricians and Gynecologists (2013)

has reaffirmed that although observational data were consistent with the possibility that subclinical hypothyroidism was associated with adverse neuropsychological development, there have been no interventional trials to demonstrate improvement.

• College thus has consistently recommended against implementation of screening until further studies are done to validate or refute these findings.

• The American Thyroid Association, and the American Association of Clinical Endocrinologists now uniformly recommend screening only those at increased risk during pregnancy


Isolated Maternal Hypothyroxinemia• Women with low serum free T4 values but a normal range TSH

level are considered to have isolated maternal hypothyroxinemia.• 2.1-percent incidence in the FASTER Trial.• Offspring of women with isolated hypothyroxinemia have been

reported to have neurodevelopmental difficulties at age 3 weeks, 10 months, and 2 years.

• CATS study did not find improved neurodevelopmental outcomes in women with isolated hypothyroxinemia who were then treated with thyroxine.

• Because of this, routine screening for isolated hypothyroxinemia is not recommended.


Postpartum thyroiditis

• Transient autoimmune thyroiditis is consistently found in approximately 5 to 10 percent of women during the first year after childbirth.

• Postpartum thyroid dysfunction with an onset within 12 months includes hyperthyroidism, hypothyroidism, or both.

• Up to 50 percent of women who are thyroid-antibody positive in the first trimester will develop postpartum thyroiditis.


Nodular Thyroid Disease

• Thyroid nodules can be found in 1 to 2 percent of reproductiveaged women.

• Management of a palpable thyroid nodule during pregnancy depends on gestational age and mass size.

• An important consideration is that, although rare overall,90% of thyroid cancers present as thyroid nodules.


• Carcinomas derived from thyroid epithelium may be papillary, follicular (differentiated), or undifferentiated.

• Only those nodules thought to be malignant need further investigation or treatment, which is usually by surgery with or without radioiodine.


Diagnosis

• Outside pregnancy, radioiodine is used to distinguish “cold” (more likely to be malignant) from “hot” (functioning) nodules. Which is contraindicated in pregnancy.

• Ultrasound, therefore, forms the main investigative tool.

• Fine-needle aspiration should be reserved for rapidly enlarging nodules, cystic nodules larger than 4 cm or solid nodules larger than 2 cm.55


Management


Take home message

• Thyroid disorder is common in general population as well as common in pregnant mother.

• By treating and preventing thyroid condition we can preserve maternal as well as fetal life.

• Treatment is easy only things required is early diagnosis and proper management.

Thank you

• James, Steer, Weiner.Thyroid disease: in High risk pregnancy management option, fourth edition, uk , elsevier, 2006 pp 813-829.

• Cunninghams . Endocrine disorders: In Williams Obstetrics, 24th Edition, New York, Mac Graw Hill , 2014 pp 1147.

• Richard F .Thyroid anatomy In GRAY’S Anatomy, third edition , Elseveir, uk , 2015

• Kim E. Thyroid Physiology In Ganong’ Review of Medica Physiology, 24th edition, New York, Mac Graw Hill , 2012.

Thyroid disease in Pregnancy

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