Special Situations In Hyperthyroidism

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Thyroid Crisis or Thyroid STORM

Rapid deterioration of hyperthyrodism with Hyperpyrexia, severe tachycardia, extreme restlessness, Cardiac Failure & Liver Dysfunction.

Precipitated by:

Stress

Infection

Surgery in unprepared patient.

Radioiodine Therapy

Treatment is urgent:

Propranolol

Potassium Iodine

Anti-thyroid drugs

Corticosteroids

Control Cardiac Failure and Tachycardia

Complications

Thyrotoxic cardiomyopathy - Ischaemic changes in a 12-lead EKG (Reverse after reversion to euthyroidism)

T-wave Inversion

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Hyperthyroidism in Pregnancy and Neonatal Life

Pregnancy common occurs during Anti-thyroid treatment

PTU is preferred during pregnancy or in cases pregnancy is planned.

Congenital abnormalities have been described with Carbimazole

HCG (High in Pregnancy) - weak stimuator of TSH receptor

Suppressed TSH with slightly raised fT4/fT3 in first trimester.

Associated with Hyperemesis gravidarum.

Investigate using TSH levels

Pathology is usually always Graves' disease.

Thyroid Stimulating Immunoglobulins (TSI) cross the placenta and stimulate fetal thyroid.

Carbimazole and PTU also cross placenta.

T4 doens't cross very well.

Block and Replace regimen is contraindicated.

Use the smallest PTU dose possible - Monitor Fetus!

If neccesary, Surgery may be performed, preferably in 2nd trimester.

Radioactive Iodine is absolute contraindication.

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The Fetus and Maternal Grave's disease

Mother may have circulating TSI

Even if euthyroid after surgery or RAI

Fetus can thus become hyperthyroid

Monitor during pregnancy

Fetal Heart - monthly (rates above 160 bpm suggest hyperthyroidism

Maternal Treatment with Propranolol and/or PTU.

Direct measurement of TSHR-Ab may predict neonatal thyrotoxicosis.

Prevent euthyroid mother becoming hypothyroid

T4 is given (does not cross the placenta)

Contraindications

sympathomimetics - used to prevent premature labor

Informed Paedriatician and check infant after birth - over treatment with PTU or Carbimazole may cause goitre in baby.

Breast feeding while on anti-thyroid is safe.

Hypterthyroid manifestations in New born:

Irritability

failure to thrive

persisting weight loss

diarrhea

Eye Signs

TFTs are unreliable as they differ with age.

Untreated Neonatal Hyperthyroid is assocaited with hyperactivity in later life.

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Thyroid Hormone Resistance

Inherited

Mutations in thyroid hormone receptor

High Levels of T4 with Normal TSH levels

Two consequnences

TFTs appear abnormal even when patient is euthyroid and requires no treatment - Specialist review is required to differencitate between hyperthyroidism and inappropriate TSH secretion.

Certain tissues may have normal activity.

level of thyroid hormones at maintain euhyroidism at pituitary and hypothalamic levels may be higher than that required in other tissues e.g. heat and bone.

Tissues may exhibit thyrotoxic effects in spite of normal TSH .

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Long-Term Consequences of Hyperthyroidism

Sight increase in mortality

Increased risk of osteoprosis

AF - thromboembolic disease.

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