Autoimmune Thyroid Disease and Pregnancy Clinical Presentation

Symptoms of hyperthyroid can be easily confused with symptoms of the hypermetabolic state of pregnancy. Mild hypothyroid symptoms can be difficult to distinguish from the common aches and pains of pregnancy. Obtaining a careful patient history is essential in the evaluation of women thought to have thyroid dysfunction.

Hyperthyroidism

• Patients with hyperthyroidism usually report loss of concentration, nervousness, and emotional lability.

• Tremor, heat intolerance, excessive sweating, palpitations, and hyperdefecation are also common findings.

• Patients may report having difficulty with climbing stairs; this is a sign of proximal muscle weakness.

• Some patients may report that their neck is getting bigger than it was before. This change is caused by the enlarged thyroid gland.

Hypothyroidism

• Untreated patients with moderate-to-severe hypothyroidism have impaired fertility. As a result, women with this disease are rarely pregnant at the time of presentation.

• Symptoms of mild hypothyroidism can mimic those of normal pregnancy, making diagnosis difficult.

• Lethargy, weight increase, and constipation are commonly reported.

• Patients frequently report having cold intolerance, stiffness, muscle cramping, carpal tunnel syndrome, dry hair and skin, and a deepened voice.

Postpartum thyroiditis

• PPT has 3 phases:

  1. Hyperthyroid phase, when thyroid hormones are being released because of thyroid destruction

  2. Hypothyroid phase

  3. Resolution, or euthyroid, phase

• The most common time for women present with PPT is 1-8 months after delivery, with a peak incidence at 6 months. This timing is important because the process may overlap with the next pregnancy in women who have short pregnancy intervals.

• Depending on the stage of disease at the time of presentation, patients may have symptoms of hyperthyroid or hypothyroid, as outlined above.

Subclinical hypothyroidism

• Subclinical hypothyroidism affects 2-3% of women in pregnancy.

• The symptoms of subclinical hypothyroidism are vague and nonspecific.

• The diagnosis is based on a normal level of free thyroxine (FT4) and an elevated TSH level.

Hyperthyroidism

• General appearance: In general, patients with hyperthyroidism are restless, anxious, and fidgety.

• Skin and hair: The patient's skin is warm and moist, with a velvety texture, and their hair is fine and silky.

• Eyes

  • The eyes usually have a characteristic stare, with a widened palpebral fissure.

  • Lid lag and failure to wrinkle the brow during the upward gaze are common findings.

  • With careful observation, infrequent blinking is noted.

  • With the infiltrating ophthalmopathy of Graves’ disease, potential findings include proptosis, ophthalmoplegia, chemosis, conjunctivitis, periorbital swelling, corneal ulceration, optic neuritis, and optic dystrophy.

• Thyroid

  • A goiter is present in almost every pregnant patient with Graves’ disease.

  • The gland is diffusely enlarged, usually 2-4 times normal.

  • The gland can be soft or firm, and it is seldom tender to palpation.

  • A thrill or bruit may be present.

  • Thoroughly examine the thyroid gland for nodules. The presence of a nodule requires further workup during pregnancy to rule out malignancy.

• Heart

  • Findings on cardiac examination include a wide pulse pressure due to increased systolic pressure and decreased diastolic pressure.

  • Sinus tachycardia is common. A resting tachycardia greater than 100 bpm that does not change with Valsalva is helpful in distinguishing hyperthyroid tachycardia from that of pregnancy.

  • Atrial arrhythmias can also be found on examination. These usually occur in the form of atrial fibrillation.

  • Other findings are systolic murmurs, an increased intensity of the apical first sound, cardiac enlargement, and cardiac failure.

• Nails

  • Separation of the nail from the distal nail bed, known as onycholysis or Plummer nail, can often be found when the extremities are examined. The ring fingers are most commonly affected.

  • Fine tremor of the fingers and hyperreflexia can also be noted.

Fetal thyroid dysfunction

• Suggestive findings

  • Fetal tachycardia (fetal heart rate >160 bpm)

  • Intrauterine growth restriction

  • Fetal goiter

  • Hydrops

• Causes

  • The risk of fetal or neonatal thyrotoxicosis is related to the mother's level of thyroid receptor–stimulating antibodies because the antibodies freely cross the placenta.

  • Fetal or neonatal hypothyroidism may also be due to maternal use of antithyroid drugs (ATDs), as these cross the placenta.

• Diagnosis and screening

  • Fetal diagnosis may rarely require umbilical cord sampling to differentiate hyperthyroidism from hypothyroidism. Amniotic fluid levels can be used for diagnosis.

  • In women with a past or current history of autoimmune thyroid disease, thyroid antibody values should be checked at the end of the first pregnancy. For those with positive results for thyroid receptor–stimulating antibodies or those taking ATDs, fetal ultrasonography should be performed at least monthly after 20 weeks of gestation.

• Treatment

  • Fetal thyroid dysfunction is treated with adjustment of maternal ATD therapy.

  • Fetal hypothyroidism may require intra-amniotic administration of T4.

Hypothyroidism

• Motor function and cognition: Patients with hypothyroidism appear to have slowing of speech and movement. They can also be forgetful and exhibit difficulty with concentration.

• Skin: The skin is usually dry, pale, and yellowish.

• Hair: Hair is thin, brittle, and sparse.

• Head, eyes, ears, nose, and throat

  • Auditory acuity may be decreased.

  • Eye examination may reveal periorbital puffiness.

  • A large tongue and an expressionless face can be observed in patients with severe disease.

• Thyroid gland

  • A goiter associated with Hashimoto thyroiditis is firm, diffusely enlarged, and usually painless to palpation.

  • In patients with atrophic chronic thyroiditis, the thyroid gland may be normal or not palpable.

• Heart

  • A low-normal heart rate is common.

  • The heart can be enlarged if it is dilated.

  • Pericardial effusion is present in severe cases.

• GI tract

  • Bowel sounds may be decreased or absent.

  • Paralytic ileus has been reported in severe cases of hypothyroidism.

• Extremities: Examination of the extremities may reveal nonpitting edema and hyporeflexia, with prolongation of the relaxation phase of the reflex response.

• Fetus: Fetal examination usually reveals normal findings in mild cases.

Postpartum thyroiditis

• Presenting findings: Patients with PPT can present with symptoms of hyperthyroidism or hypothyroidism, depending on the stage of disease.

• Phases of disease: As many as one third of women with PPT present with hyperthyroidism at 1-4 months after birth. This period is followed by a hypothyroid phase lasting as long as 2 months. Recovery then ensues.

• Physical stigmata of Graves disease will be absent (goiter with a bruit, endocrine ophthalmopathy).