Gibney J, Smith TP, McKenna TJ. The impact on clinical practice of routine screening for macroprolactin.
J Clin Endocrinol Metab 2005;
90:3927-32. [PMID:
15811931 DOI:
10.1210/jc.2004-2234]
[Citation(s) in RCA: 87] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
BACKGROUND
Macroprolactin has reduced bioactivity in vivo and accumulates in the sera of some subjects, resulting in pseudo-hyperprolactinemia and consequent misdiagnosis.
METHODS
We have audited our experience of routine screening for macroprolactin using polyethylene glycol (PEG) precipitation over a 5-yr period in a single center.
RESULTS
Application of a reference range for monomeric prolactin (the residual prolactin present in macroprolactin-depleted serum) for normal individuals revealed that 453 of 2089 hyperprolactinemic samples (22%) identified by Delfia immunoassay were explained entirely by macroprolactin. The percentage of hyperprolactinemic samples explained by macroprolactinemia was similar across all levels of total prolactin (18, 21, 19, and 17% of samples from 700-1000, 1000-2000, 2000-3000, and greater than 3000 mU/liter, respectively). Application of an absolute prolactin threshold after polyethylene glycol treatment of sera, rather than the traditional method, i.e. less than 40% recovery, minimizes the opportunity for misclassification of patients in whom macroprolactin accounted for more than 60% of prolactin and the residual bioactive prolactin was present in excess. Macroprolactinemic patients could not be differentiated from true hyperprolactinemic patients on the basis of clinical features alone. Although oligomenorrhea/amenorrhea and galactorrhea were more common in patients with true hyperprolactinemia (P < 0.05), they were also frequently present in macroprolactinemic patients. Plasma levels of estradiol and LH and the LH/FSH ratio were significantly greater in macroprolactinemic compared with true hyperprolactinemic subjects (P < 0.05). Reduced use of imaging and dopamine agonist treatment resulted in a net cost savings, offsetting the additional cost associated with the introduction of screening.
CONCLUSION
Routine screening of all hyperprolactinemic sera for macroprolactin is recommended.
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