Hypothyroidism (myxoedema)

Clinical Description

Hypothyroidism is a condition associated with reduction in thyroid hormone production.

Thyroid hormone is required for normal metabolism and growth. Its deficiency has major consequences on fetal development as well as intellectual and physical development in infants and children (cause of cretinism). In adults, it may be the cause of several problems.

Causes:

• Antibody-related thyroid gland destruction (Hashimoto thyroiditis)
• Subtotal thyroidectomy
• Pituitary surgery or lesions
• Congenital
• Severe iodine deficiency
• Drug induced (e.g., radioiodine therapy, amiodarone etc.)

Signs and Symptoms

• Cretinism in infants: Poor growth, development, and poor school performance in

Children

• Signs Neonate: Prolonged neonatal jaundice, Excessive sleep, Feeding problems
• Cretinism in Children: mental sub-normality, short stature, large tongue, dry skin, sparse hair, protuberant abdomen, umbilical hernia, abnormal facies)
• Adults: menstrual irregularity and infertility, mental health conditions and dementia.
• General fatigue, constipation, cold intolerance, dry and coarse skin, hoarse voice, weight gain, bradycardia (slow heart rate, slow relaxing reflexes, hyperlipidaemia, goitre (+/-), dementia, pallor, puffy face, hair loss and eyebrow loss

Investigations

• Thyroid function tests T3, T4, TSH.
• Fasting blood lipids (for elevated cholesterol level)
• Full blood count

Treatment

• Treatment objectives are to correct blood level of thyroid hormones and to maintain lifelong normal levels of thyroid hormones

Pharmacological

• Start treatment with a low dose of Levothyroxine, especially in the elderly, those with heart disease and Children (e.g., 25-50 microgram), and adjust dose as appropriate every 2-8 weeks until TSH levels are within normal reference range.

Treatment is often life-long.

Adults

• 25-200 microgram daily (can start with dose 25 to 100mcg daily)

Children

• > 12 years; 25 micrograms daily (max. 200 micrograms)
• 2-12 years; 25 micrograms daily (max. 100 micrograms)
• < 2 years; 25-75 micrograms daily.

Monitor thyroid function tests where possible to avoid over or under treating.

Complications and Referral Criteria

• All cases need to be managed by a doctor/specialist