Understanding Hyperprolactinaemia: Causes, Diagnosis, and Treatment

Hyperprolactinaemia is a condition characterized by elevated levels of prolactin in the blood, particularly prevalent among women experiencing amenorrhoea or abnormal lactation (galactorrhoea). To confirm this condition, multiple stress-free blood tests are necessary. It is essential to rule out other potential causes, such as pregnancy, primary hypothyroidism, and various medications, before arriving at a diagnosis.

Several factors can contribute to hyperprolactinaemia. Moderate elevations in prolactin levels, ranging from 500 to 2000 mU/L (approximately 25–100 ng/mL), may be linked to primary hypothyroidism, certain medications—such as dopamine receptor antagonists, opioids, and some antihypertensives—stress, or chronic conditions like renal failure and cirrhosis. More significant increases, particularly above 3000 mU/L (around 150 ng/mL), often suggest the presence of a microprolactinoma, while levels exceeding 6000 mU/L (approximately 300 ng/mL) are indicative of a macroprolactinoma.

When diagnosing hyperprolactinaemia, it is crucial to assess overall pituitary health. A pituitary tumor, commonly a microprolactinoma in women of reproductive age, is often the underlying cause. In some cases, associated conditions like acromegaly or stalk disconnect syndrome can complicate the picture, necessitating a thorough evaluation of the anterior pituitary's function and potential imaging studies, such as an MRI.

Treatment for hyperprolactinaemia primarily targets the underlying cause. For instance, if the condition arises from certain medications, it may require a careful reassessment of the patient's drug regimen, often in collaboration with mental health professionals. In cases of primary hypothyroidism, appropriate hormone replacement therapy is essential. However, the cornerstone of treatment for prolactinomas is the use of dopamine agonists, such as cabergoline, which have proven highly effective in reducing prolactin levels and shrinking tumors.

Dopamine agonists are preferred over older medications like bromocriptine due to their improved tolerability and efficacy. Patients undergoing treatment for hyperprolactinaemia can expect rapid relief from symptoms, including the potential restoration of fertility and prevention of bone density loss, which can occur due to prolonged low estrogen or testosterone levels.

Overall, understanding hyperprolactinaemia involves recognizing its diverse causes, confirming diagnosis through appropriate testing, and implementing effective treatments tailored to the underlying issues.