Q I am a 67-year-old woman. I had both my thyroid glands removed earlier this year due to cancer. I am on thyroxine 50mg, a thyroid hormone replacement therapy.

Since the surgery, I have not been able to sleep without the help of Lexotan. Doctors tell me it is due to my mind and not the medication.

I completed my radioactive iodine treatment a couple of months ago. Since all my treatments are done, there should be no more worries.

But I still cannot sleep.

My doctor has given me a week's worth of Lexotan. My main worry is running out of Lexotan and not being able to sleep.

Where should I get help?

A Cancer occurs when normal cells undergo certain changes which cause the cells to grow and multiply rapidly in an abnormal manner.

The accumulated abnormal cells then form a tumour, which has the potential to spread and invade nearby normal tissue and elsewhere in the body.

There are several forms of thyroid cancers. The most common type is known as papillary thyroid cancer, which has a good prognosis and survival rate, especially if detected and treated early.

But, as with all cancers, the overall risk depends on the type of thyroid cancer, the size of the tumour and whether it has spread to other tissues in the body.

Thyroid cancer commonly occurs in adults. Although previous exposure to radiation in the neck is a risk factor, no risk factors can be found in many patients.

The standard treatment after surgery for thyroid cancer is to go for radioactive iodine to wipe out any remaining cancer cells.

This treatment will result in low thyroid hormone levels, which means patients have to be put on life-long thyroxine (thyroid hormone) replacement.

One other important reason for thyroxine replacement is to suppress a hormone called the thyroid-stimulating hormone or TSH.

Studies have shown that TSH suppression can reduce the risk of a relapse.

Even with surgery, radioactive iodine and TSH suppression with thyroxine, thyroid cancer can still recur.

Relapses often occur within the first few years after surgery.

Although the risk gets lower with time, relapses can still occur many years later, which is why thyroid cancer patients need to go for follow-up checks for life.

Importantly, if detected early, most recurrences can be treated.

The dose for the thyroxine must be high enough to minimise the risk of a relapse, yet not so high as to result in side effects that are intolerable to the patient.

Some of the effects of overtreatment may include palpitations, anxiety, osteoporosis, heat intolerance, sweating and weight loss.

It is possible that your insomnia may be related to the thyroxine and a simple blood test to measure the thyroid hormone level may be a helpful first step to understand if your thyroxine is contributing to the insomnia.

Another possibility is that the insomnia is unrelated to the thyroxine.

Hence, I would suggest having a detailed discussion with your doctor regarding both these possibilities.

Finally, it is important to remember that maintaining a healthy and active lifestyle - through eating healthy, well- balanced meals, engaging in regular exercise, having adequate rest and learning how to manage simple life stressors - can go a long way in improving your overall well-being.

Dr Goh Kian Peng

Medical director and endocrinologist at the St Julien Clinic for Diabetes and Endocrinology at Mount Alvernia Hospital.

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