Hypothyroidism

Notes
  • It is an endocrine disorder that results from deficiency of thyroid hormone.
  • It is more prevalent in elderly.
  • Its causes include:
    _Iodine deficiency (the major cause)

_Congenital hypothyroidism (crenitism)

_Drug-induced hypothyroidism (e.g. by

  lithium, amiodarone, interferon-alfa

  and tyrosine kinase inhibitors such as

  imatinib and erlotinib)

_After thyroidectomy

_Following radio-iodine therapy

_Following pituitary surgery or damage

_Auto-immune thyroiditis (Hashimoto disease)

Symptoms
  • Firm goiter that may progress to a shrunken fibrotic thyroid that is non-functional.
  • Intellectual disability
  • Lethargy
  • Prolonged neonatal jaundice
  • Delay mental and physical development
  • Weight gain
  • Myalgia
  • Joint pains
  • Macroglossia and resultant effects on

the speech

  • Apnoiec attacks
  • Constipation
  • Amnesia
  • Disturbance of menstrual cycle
  • Blurred vision
  • Psychiatric manifestations
  • Reduced fertility
  • Large abdomen
  • Umbilical cord hernia
  • Somnolence
  • Cold intolerance
  • Dry hair
  • Challenges in feeding
  • Bradycardia
  • Dry skin
  • Hoarse voice
  • Failure to thrive
  • Myxedema (non-pitting edema)
  • Pitting edema
  • Hypotension
Diagnosis
  • Physical examination.
  • TSH assays (elevated TSH).
  • Free thyroxine, T4, or the free thyroxine index, FTI (reduced levels).
  • Full Blood Count, FBC
Management
  • Levothyroxine (l-thyroxine) at the following dose:

_Neonate:Tabs 10µg/kg/day (increased at a dose of 5µg/kg/day fortnightly  to max. dose 25-37.5µg/day).

_Children one month to 12yrs:  Tabs 5-10µg/kg/day (increased at a dose of 25µg/kg /day2-4 weekly.

_Children 12-18yrs:  Tabs 50-100µg/day (increased at a dose of 50µg/day 3-4 weekly to a maintenance dose of 100-200µg/day

  • For myxedema coma: T4 IV and corticosteroids and other supportive measure.
  • Mass salt iodization to reduce endemic goiter.
  • After stabilization of dosage, patients need to be reviewed annually
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