Frequency of Macroprolactin in Hyperprolactinemia

To determine the frequency of Macroprolactin (MaPRL) in patients with increased total prolactin and its clinical and financial impact.

Cross-sectional study.

Section of Clinical Chemistry, Department of Pathology and Laboratory Medicine, The Aga Khan University Hospital, Karachi, from March to May 2015.

Patients with high total prolactin were screened by polyethylene glycol (PEG) precipitation for determination of MaPRL. Clinical history, imaging work-ups, and cost incurred in further investigations were collected by telephonic interview after verbal consent. Patients were stratified into true hyperprolactinemia and macroprolactinemia after PEG treatment, based on monomeric prolactin levels. Medical records of cases registered with AKUH were reviewed to confirm the diagnosis.

Two hundred and thirty-nine patients were identified with high prolactin levels. Macroprolactinemia was identified in 145 (60.7%) and true hyperprolactinemia in 94 (39.3%) patients. Galactorrhea was significantly more in true hyperprolactinemic females (p=0.022), followed by visual disturbances (p=0.01) and headache (p=0.006). Moreover, as majority of population were females, the clinical features in the macroprolactinemia group as compared to true hyperprolactinemic group were mostly related to non-pituitary causes like drug intake [42.5% (54) vs. 37% (30)], heat intolerance due to thyroidal illness [41.7% (53) vs. 38.3% (31)] and surgery [26.8% (34) vs 22.2% (18)] in females. Further radiological workup (MRI, CT) were conducted in 35 (37.2%) patients with true hyperprolactinemia. Twenty-one (60%) of the patients were confirmed to have pituitary adenomas. In eight (5.5%) patients with MaPRL, only one had pituitary microadenoma on radiological workup. Total cost impact on the basis of investigations, was significantly higher in the group undergone imaging, despite 7 out of 8 individuals found to have normal imaging results. The median total cost in true hyperprolactinemic group undergone imaging was Rs. 4370 (IQR=2412.5, 22850) as compared to macroprolactinemic groups; Rs. 3,250 (IQR=2150, 4278). There was significant difference in the cost burden of both the groups (p <0.001).

High frequency of MaPRL was identified in patients with hyperprolactinemia. Screening with PEG precipitation in hyperprolactinemic sera is simple and cost-effective.