(GP)

Overview

• Condition in which the thyroid gland is underactive, resulting in deficiency of the thyroid hormones T3 & T4
• Congenital → thyroid dysplasia or aplasia
• Acquired → hashimoto's thyroiditis (autoimmune), postpartum thyroiditis, de quervain thyroiditis, Iatrogenic (post-surgery)
• Secondary Hypothyroidism → pituitary disorders (eg. pituitary adenoma) → TSH deficiency
• Lithium Toxicity can cause hypothyroidism
• F>M (6:1)
• Amboss Summary Image

Subclinical Hypothyroidism (may occur in inter-currant illness) ⇒ high TSH with normal T3 and T4. TFTs should be repeated in 3-6 months.

Making Diagnosis

Clinical Features:

• Decreased Basal Metabolic Rate → slow cognition, apathy, dry skin, cold intolerance
• Decreased Sympathetic Activity → decreased sweating, constipation, bradycardia
• Fatigue, hair loss, weight gain (despite poor appetitie)
• Depression