hypothyroidism%20(pediatric)
HYPOTHYROIDISM (PEDIATRIC)
Hypothyroidism is due to decreased or absent production of thyroid hormone.
Primary hypothyroidism is caused by generalized tissue resistance to thyroid hormone and disorders that affect the thyroid gland directly. It is responsible for majority of hypothyroid cases.
Central hypothyroidism is caused by hypothalamic or pituitary disorders.

Introduction

  • Congenital hypothyroidism is one of the most common preventable causes of mental retardation
  • Acquired hypothyroidism is the absence or decrease in the production of thyroid hormone

Etiology

Acquired Hypothyroidism

  • Primary acquired hypothyroidism: Caused by generalized tissue resistance to thyroid hormone & disorders that affect the thyroid gland directly
    • Responsible for majority of hypothyroid cases
    • Etiologies: Chronic autoimmune (Hashimoto’s) thyroiditis, iodine deficiency/excess, thyroid surgery, radioactive iodine therapy, external irradiation, infiltrative disorders, drugs, agenesis/dysgenesis of the thyroid
  • Central acquired hypothyroidism: Caused by hypothalamic or pituitary disorders
    • Etiologies: Pituitary tumors, metastasis, hemorrhage, necrosis, aneurysms, surgery/trauma, infiltrative disorders, infectious diseases, chronic lymphocytic hypophysitis, other brain tumors, congenital abnormalities, defects in thyrotropin-releasing hormone (TRH), thyroid-stimulating hormone (TSH) or both
  • May also be classified as congenital or acquired (symptoms manifest after a period of normal functioning)

Congenital Hypothyroidism

  • Permanent cases result from dysgenesis/agenesis of thyroid gland or a defect in thyroid hormonogenesis
  • Transient cases due to transplacental passage of maternal medication, maternal blocking antibodies or iodine deficiency/excess
  • Rare cases due to central hypothyroidism

Signs and Symptoms

Acquired Hypothyroidism

  • Goiter
  • Lethargy, ataxia, dull facial expressions
  • Slow growth & short stature, delayed bone age & dentition
  • Immature upper to lower body proportions
  • Cool, dry, jaundiced skin; dry, coarse hair, brittle nails
  • Obstructive sleep apnea (OSA)
  • Cold intolerance
  • Constipation, galactorrhea
  • Hoarseness
  • Memory & mental impairment, decreased concentration, depression
  • Precocious sexual development, irregular or heavy menses, infertility
  • Hyperlipidemia
  • Myxedema
  • Weight gain despite decreased appetite
  • Bradycardia

Congenital Hypothyroidism

  • Large fontanelles
  • Prolonged indirect jaundice, constipation
  • Hypothermia; cool, dry skin
  • Noisy respirations, hoarse cry
  • Goiter
  • Delayed relaxation of deep tendon reflexes, decreased activity level
  • Elevated birth weight despite poor feeding
  • Pooling of secretions, large protruding tongue
  • Myxedema of eyelids, hands, scrotum
  • Bradycardia
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