Hyperprolactinaemia: when MRI is indicated?


Design This prospective study was carried out at the magnetic resonance imaging (MRI) unit at the department of diagnostic imaging of Al-Kadhmiya Teaching Hospital over a period of 26 months. Objective: To establish a strategy for the use of MRI of the pituitary region in patients with hyperprolactinaemia based on the possibility of finding a pathology in the pituitary region as a cause of hyperprolactinaemia with respect to serum prolactin (PRL) as well as the analysis of serum PRL in relation to the size of adenoma in the pre & post medical treatment evaluation to determine the need for MRI in the follow up in patients with pituitary adenoma. Subjects & Methods We selected 69 women recently found to have clinical & biochemical evidence of hyperprolactinaemia with serum PRL exceeding the double the upper normal level of the control. MRI of the pituitary region & serum PRL were assessed at the initial presentation for all patients & after the institution of bromocriptine (BRC) treatment for 28 patients who were shown to have either micro or macroadenomas at the initial MRI. The diameter of the adenoma served as a predictor for its size & was considered for correlation with serum PRL level at the follow up period of 3 , 6 & 12 months of treatment. Results At the initial MRI, 27 patients had microadenomas (39.1%), 12 patients had macroadenomas (17.4%), 9 patients had empty sella turcica (13.1%), and 21 patients (30.4%) had no obvious abnormality in the pituitary region The analysis of individual serum PRL level to establish a cut-off point of serum PRL above which all cases were positive for a pathology in the pituitary region on MR imaging, revealed a cut-off value = 84.6 ng/ml. A strong correlation has been found between the size of adenoma and serum PRL level at the initial presentation as well as at the follow up assessment that revealed a parallel reduction in adenoma diameter & serum PRL level. Conclusion MRI of the pituitary region is justifiable in women with hyper-prolactinaemia when serum PRL level is approximately two & a half folds of the upper normal level where its likely to reveal an abnormality , but it should not be used routinely for the follow up of patients on treatment as the assessment of serum PRL level will suffice as a predictor of tumor shrinkage unless there is no response to medical treatment or the patient developed new symptoms that suggest increase in the size of the adenoma or involvement of the surrounding structures.