Author/Authors :
Yener, Serkan Dokuz Eylul University - School of Medicine - Department of Internal Medicine, Division of Endocrinology and Metabolism, Turkey , Comlekci, Abdurrahman Dokuz Eylul University - School of Medicine - Department of Internal Medicine, Division of Endocrinology and Metabolism, Turkey , Arda, Nuri Dokuz Eylul University - School of Medicine - Department of Neurosurgery, Turkey , Men, Suleyman Dokuz Eylul University - School of Medicine - Department of Radiology, Turkey , Yesil, Sena Dokuz Eylul University - School of Medicine - Department of Internal Medicine, Division of Endocrinology and Metabolism, Turkey
Abstract :
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.
