One of my patients has just attended for a routine eye examination. When I asked about her general health she told me she felt tired all the time and her skin had become dry. Her friends had told her that she had a low mood and had put on some weight. She denied taking any medication and had no eye disease. What is going on?

This sounds like an underactive thyroid, also known as hypothyroidism. This is where the thyroid gland doesn’t produce enough of the thyroid hormones.

Most cases are caused by the immune system attacking the thyroid gland and damaging it, or by damage that occurs during some treatments for an overactive thyroid or thyroid cancer.

Both men and women can have an underactive thyroid, but it’s more common in women.

An underactive thyroid can cause a wide range of symptoms, including:

• tiredness
• sensitive to cold
• weight gain
• constipation
• depression
• slow movements and thoughts
• muscle aches and weakness
• muscle cramps
• dry and scaly skin
• brittle hair and nails
• loss of libido
• pain, numbness and a tingling sensation in the hand and fingers also known as carpal tunnel syndrome
• irregular periods or heavy periods.

Symptoms usually develop slowly and a person may not realise they have a medical problem for several years.

An underactive thyroid (hypothyroidism) isn’t usually associated with eye disease. In severe cases, however, hypothyroidism may cause swelling around the eyes and a loss of the hairs in the outer part of the eyebrows.

Patients may mention these types of symptoms when asked about their general health during an eye examination.

Note them in the clinical records, take heed of them and refer the patient to their general practitioner.

The diagnosis can be tricky as many of symptoms of underactive thyroid are the same as those of other conditions, so it can easily be confused for something else.