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Clinical and radiological features of patients with macroprolactinaemia
Mark W J Strachan1, Wei Leng Teoh, Andrew C Don-Wauchope
1Metabolic Unit, Western General Hospital, Edinburgh and Department of Clinical Biochemistry, Royal Infirmary of Edinburgh, Edinburgh, UK. mark.strachan@luht.scot.nhs.uk
Objectives:
Macroprolactin is a complex of prolactin (PRL) and IgG and may account for a significant proportion of cases of 'idiopathic hyperprolactinaemia'. In this study, we sought to determine the prevalence and clinical features of macroprolactinaemia in patients diagnosed with hyperprolactinaemia in our region, with a view to determining how patients with macroprolactinaemia should be investigated and managed.
Patients And Methods:
An Immuno-1 automated immunoassay system with polyethylene glycol (PEG) precipitation was used to identify macroprolactin, with a recovery of 700 mU/l. The clinical records of 51 (44 female) were available for retrospective review.
Results:
The mean (range) age of patients was 39.5 (18-82) years. The median (range) concentrations for the various forms of PRL were: total PRL 1130 mU/l (728-5116), monomeric PRL 240 mU/l (50-656) and macroprolactin 895 mU/l (381-4854). Classical symptoms of hyperprolactinaemia were present in 39% of patients, although in many there were other possible explanations for their symptomatology. Pituitary adenomas were identified in six out of 36 people who underwent neuroimaging. Five of these patients had a microadenoma and one had a 10-mm macroadenoma (although, in this patient macroprolactin was identified after the discovery of the tumour). There was no relationship between macroprolactin concentrations and the presence of hyperprolactinaemic symptoms or neuroimaging abnormalities.
Conclusions:
Macroprolactinaemia is a common occurrence in patients with hyperprolactinaemia, but associated symptomatology may not necessarily be linked. The neuroimaging abnormalities were also probably incidental findings and it is questionable whether neuroimaging is necessary when significant macroprolactinaemia is identified and the concentration of monomeric PRL is not elevated (using the Immuno-1 assay system, following PEG precipitation).
Insights
Macroprolactinaemia, a complex of prolactin (PRL) and IgG, is common in hyperprolactinaemia patients. Its presence doesn't always correlate with symptoms or require neuroimaging if monomeric PRL is normal.
Area of Science:
- Endocrinology
- Clinical Chemistry
Background:
- Macroprolactin, a complex of prolactin (PRL) and IgG, is implicated in idiopathic hyperprolactinaemia.
- Understanding its prevalence and clinical significance is crucial for patient management.
Purpose of the Study:
- To determine the prevalence and clinical features of macroprolactinaemia in hyperprolactinaemic patients.
- To guide the investigation and management strategies for patients with macroprolactinaemia.
Main Methods:
- Utilized polyethylene glycol (PEG) precipitation with an automated immunoassay to detect macroprolactin.
- Identified macroprolactin in 21% of patients with elevated total PRL (>700 mU/l).
- Conducted a retrospective review of clinical records for 51 patients.
Main Results:
- Macroprolactinemia was identified in 58 (21%) of 273 patients.
- Classical hyperprolactinaemia symptoms were present in 39% of patients, with other potential causes.
- Pituitary adenomas were found in 6/36 patients undergoing neuroimaging, likely incidental findings.
Conclusions:
- Macroprolactinaemia is a frequent finding in hyperprolactinaemia but may not correlate with symptoms.
- Neuroimaging may not be necessary for macroprolactinaemia if monomeric PRL levels are normal.