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Underactive thyroid

With an underactive thyroid, the body produces too little thyroid hormone. Symptoms often develop gradually and are non-specific; blood tests confirm the diagnosis. Levothyroxine helps when treatment is needed, but the dose and monitoring must be tailored to the individual.

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With an underactive thyroid, the body produces too little thyroid hormone. Symptoms often develop gradually and are non-specific; blood tests confirm the diagnosis. Levothyroxine helps when treatment is needed, but the dose and monitoring must be tailored to the individual.

  • Fatigue, feeling cold, slower thinking, low mood or needing more sleep.
  • Dry skin, hair loss, brittle nails, hoarseness or a puffy face.
  • Take levothyroxine the same way every day and follow the agreed interval before food and other products.
  • Keep iron, calcium, antacids and certain supplements separated from levothyroxine by the recommended interval.
  • Make an appointment for persistent compatible symptoms, an abnormal TSH/free T4 result or swelling in the neck.
  • For urgent GP care outside normal opening hours, call HAP 9252. Call Ambulance 912 only for an immediately life-threatening situation.

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Overactive thyroidWith an overactive thyroid, there is too much thyroid hormone in the body. Palpitations, weight loss, trembling and heat intolerance are common, but the cause must be established through blood tests; high fever, severe agitation and a very fast heart rate can indicate a rare thyroid storm.
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Raised TSH with normal thyroid hormoneRaised TSH with normal free T4 is often called subclinical hypothyroidism. It does not always mean the thyroid is permanently underactive: the result may be temporary and many people have no symptoms. Repeat testing and assessment in the individual's context prevent unnecessary treatment.
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