LETTER TO EDITOR: RESPONSE: Importance of screening for macroprolactin in hyperprolactinaemic sera

Dear Editor, We thank Dr Wiwanitkit for his comments on our paper. As in many other clinical cases, we cannot stress enough the importance of correlating the laboratory results with the patient’s clinical signs and symptoms. Whenever a very high result for prolactin level is seen in the absence of any clinical features of hyperprolactinaemia, a physician should be alerted to the possibility of the patient having a case of macroprolactinaemia. The polyethylene glycol (PEG) precipitation as a screening method to exclude the presence of macroprolactin is affordable and simple to perform. We agree that this method could be made available whenever a case of macroprolactinaemia needs to be excluded. The laboratory result should preferably contain the recovery value (in percentage- 40%)4 given together with the real value of PRL in mIU.