Criteria for dopamine agonist resistance Although various dopamine agonists are currently effective in lowering prolactin levels and reducing tumor size, there are still a small number of patients who fail to achieve their therapeutic goals, i.e., are resistant to dopamine agonists, even when treated with high doses of dopamine agonists. The definition of dopamine resistance is still more controversial. For example, the inability to reduce PRL levels to normal, or/and the inability to resume menstruation, or/and the lack of tumor size reduction can be called dopamine resistance. At present, most scholars agree that primary resistance is defined as a tumor that does not decrease in size by 50% or a tumor that does not return to a normal prolactin level after 3 months of continuous application of bromocriptine 15 mg per day. The tumor volume increases again under continuous bromocriptine treatment, even if the dose of bromocriptine is increased. The resistance rate of patients with microadenomas treated with bromocriptine was 21%, while the resistance rate of macroadenomas was 29%. Delgrange et al. used the markers of aggressive adenomas, proliferating cell nuclear antigen and Ki67 index, and found an increase in these markers in bromocriptine-resistant tumors.
Treatment of dopamine-resistant patients 1. Increase the dose of the drug In patients receiving bromocriptine for 24 months, 53% of large adenomas and 43% of small adenomas did not respond to treatment. However, by increasing the dose of bromocriptine to the highest dose of 20 mg/day, 87% of the patients recovered their gonadal function, but none of the patients had normalized their prolactin levels by 24 months of follow-up.
2. Change of medication If the increased dosage of bromocriptine is still resistant or not tolerated by the patient, consider changing bromocriptine to cabergoline. Although cartegolide has fewer side effects and is well tolerated, the FDA still does not recommend doses above 2 mg/day.
3. Transsphenoidal pituitary tumor resection When patients are intolerant or drug-resistant to drugs, transsphenoidal pituitary tumor resection can be considered to restore gonadal and neurological function. (6), patients with cerebrospinal fluid nasal leakage after drug treatment; (7), patients with obvious neurological functional symptoms, etc.