Related Experiment Video
Updated: Jul 3, 2026
Homogeneous Time-resolved Förster Resonance Energy Transfer-based Assay for Detection of Insulin Secretion
Published on: May 10, 2018
Misdiagnosis due to the hook effect in prolactin assay
Serkan Yener1, Abdurrahman Comlekci, Nuri Arda
1Department of Internal Medicine, Division of Endocrinology and Metabolism, School of Medicine, Dokuz Eylul University, Izmir, Turkey. serkan.yener@deu.edu.tr
Objectives:
To describe a patient who was misdiagnosed as having a nonfunctional pituitary tumor due to the hook effect on prolactin measurements.
Clinical Presentation And Intervention:
A 45-year-old female was admitted with visual disturbances, panhypopituitarism and central diabetes insipidus due to pituitary tumor recurrence. She had been operated 4 times earlier and received cranial irradiation for a suspected nonfunctional pituitary adenoma. Serum prolactin was moderately elevated (164.5 ng/ml), but increased markedly after 1:100 dilution to 14,640 ng/ml. Diagnosis of a giant macroprolactinoma was made and cabergoline was started. Prolactin level normalized and a mild shrinkage of the tumor was achieved after 12 months of therapy.
Conclusion:
The hook effect must be kept in mind while evaluating a giant pituitary adenoma with moderately elevated prolactin levels. This way unnecessary surgical procedures or irradiation may be avoided.
Related Concept Videos
01:10Documentation of Nursing Diagnosis
In some settings, data-driven computerized decision support systems are in place, allowing for more accurate nursing diagnoses. The database within one of these systems includes diagnostic labels defining characteristics, activities, and indicators for nursing. A nurse enters assessment...
01:22Effect of Hepatic Disease on Pharmacokinetics: Pathophysiologic Assessment and Liver Function Test
01:23Hypothyroidism II: Pathophysiology