Premature utilization of MRI in the workup of mild hyperprolactinemia

Hyperprolactinemia is a common biochemical finding detected in primary care, and guidelines suggest confirmation with a second prolactin measurement to rule out spurious elevation prior to further workup. Premature magnetic resonance imaging (MRI) is a costly potential consequence of improperly worked-up hyperprolactinemia. We aimed to quantify the proportion of prematurely ordered MRI for isolated hyperprolactinemia without confirmation.

A retrospective chart review was performed between 2012-2021 in Alberta, Canada. We identified cases of mildly elevated serum prolactin (<100mcg/L, females ≥25.0mcg/L, males ≥21.0mcg/L) in patients >18 years who underwent MRI brain or sella following prolactin measurement. MRI was classified as "clinically appropriate" or "premature" based on clinical indication. Clinically appropriate and premature groups were compared based on patient age, sex, and scan year.

We identified 1,730 cases meeting inclusion criteria with a single prolactin measurement prior to MRI; over half (56.1%, n = 970) were categorized as "premature." Of the MRIs in the premature cohort, 39.4% (n = 382) reported at least one abnormal finding, most commonly microadenoma (n = 200). There was no statistically significant difference between premature and clinically appropriate groups for patient sex (p = 0.12) or year of MRI (p = 0.35), but patients in the premature group were significantly older (p < 0.01, mean difference 1.52 years, 95% CI:[0.45,2.49]).

MRI for investigation of mild hyperprolactinemia is often ordered prematurely without confirmation by repeat prolactin level and generates incidental findings of uncertain clinical significance to the presenting issue. To reduce patient stress and healthcare system burden, providers should ensure proper workup of hyperprolactinemia with repeat prolactin measurement prior to ordering MRI.