Hormone medication and weight gain

Hello, I have recently been diagnosed with prolactinoma and starting taking dostinex. I noticed a weight gain lately even though I am exercising...What would you suggest on how to decrease the weight whilst taking hormone medication? Thank you

18 August 2015

As you are probably aware a prolactinoma is a benign tumor of the pituitary gland that produces too much of a natural hormone, prolactin. 

Dostinex tablets contain the active ingredient cabergoline, which is a type of medicine called a dopamine agonist. It works by mimicking the action of a substance in the brain called dopamine. It is not a hormone. 

Prolactin is important for normal production of breast milk in women who are nursing, but otherwise it is present at low levels in both men and non-pregnant or non-nursing women. For reasons that are not well understood, prolactinomas are the most common pituitary tumor producing a hormone.

Excess production of prolactin caused by prolactinoma can have different effects on men and women. In women these effects differ in pre-menopausal and post menopausal women.

Pre-menopausal women  are very sensitive to the effects of prolactin.  These women may start producing breast milk abnormally, or have breast enlargement and tenderness even though they are not pregnant. In others, menstrual periods may become irregular or stop completely, and infertility is common. 

Postmenopausal women are not as sensitive to the effects of prolactin and as a consequence the tumor will typically present when it has grown large enough to cause compression of the normal pituitary gland which may stop functioning properly. 

This usually leads to loss of normal hormone function, which can show symptoms of hypothyroidism  such as fatigue, constipation, muscle pain, depression, cold intolerance, weight gain. In extreme causes low cortisol which can be life-threatening, with symptoms such as low blood pressure, confusion, nausea, vomiting and fever.

Unlike other pituitary tumors, most prolactinomas can be successfully treated medically, with either cabergoline (Dostinex®) or bromocriptine (Parlodel®). These drugs often reduce the size of the tumor and at the same time decrease the abnormally high level of prolactin in the blood very rapidly. Cabergoline or bromocriptine may control the tumor and bring the levels of prolactin in the blood back to normal, and they can make the tumor disappear especially if the tumor is very small. Treatment with these drugs may be continued for many years or indefinitely, but if the prolactin becomes normal or the tumor disappear these treatments can be discontinued with evidence of cure in about half of the patients treated.

The pituitary gland is responsible for balance of all hormones. Any imbalance in any of the hormones can have an effect on other hormones. For this reason I suggest that your weight gain is unlikely to be caused by Dostinex but it may be caused by imbalance in the hormones such as thyroid or cortisol. For this reason I think that you need to return to your doctor and have further investigations.

Once you know the results of the investigations and have identified the possible cause for the weight gain you can then start to look at your diet and exercise regime. Once you have the results, please feel free to contact us and we can help you further.

Answered by the Health at Hand nurses  

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