Summary
The authors report a case of a patient with giant, invasive skull base tumor extending to the parasellar area discovered incidentally during the work-up for decreased memory. The patient’s neurological exam was otherwise unremarkable. Endocrine evaluation performed at a local hospital showed a moderate hyperprolactinemia 103 ng/ml (normal up to 20 ng/ml). Given the large size of the tumor, the elevated prolactin (PRL) was interpreted to be secondary to stalk effect and patient underwent debulking surgery through a transcranial approach. Immunostaining of the excised tumor tissue was strongly positive for prolactin. His prolactin was found to be 13,144 ng/ml in our lab after surgery confirming the diagnosis of invasive giant prolactinoma. The patient developed a complete right third, fourth and sixth nerve palsy postoperatively. He was started on Cabergoline with normalization of his prolactin level and more than 50% decrease in residual tumor size over 9 months periods. There has been no clinically significant improvement in his right eye ophthalmoplegia since surgery. This case highlights the importance of ‘Hook Effect’ resulting in falsely low prolactin level, which may have significant therapeutic implication.
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Delgrange E, de Hertogh R, Vankrieken L, Maiter D,: Potential hook effect in prolactin assay in patients with giant prolactinoma Clin Endocrinol 1996, 45(4):506–507
Al Sifri S, Raef H,: The hook effect in prolactin immunoassays Saudi Med J 2004, 25(5):656–659
Barkan A, Chandler W,: Giant pituitary prolactinoma with falsely low serum prolactin: the pitfall of the “high-dose hook effect”: case report. Neurosurgery (Baltimore) 1998, 42(4):913–915 discussion 915–916
Petakov M, Damjanovic S, Nikolic-Durovic M, Dragojlovic Z, Obradovic S, Gligorovic M, Simic M, Popovic V,: Pituitary adenomas secreting large amounts of prolactin may give false low values in immunoradiometric assays. The hook effect. J Endocrinol Invest 1998, 21(3):184–188
Schofl C, Schofl-Siegert B, Karstens J, Bremer M, Lenarz T, Cuarezma J, Samii M, von zur Muhlen A, Brabant G,: Falsely low serum prolactin in two cases of invasive macroprolactinoma Pituitary 2002, 5(4):261–265
Haller B, Fuller K, Brown W, Koenig J, Eveland B, Scott M,: Two automated prolactin immunoassays evaluated with demonstration of a high-dose“hook effect”in one Clin Chem (Washington, DC, United States) 1992, 38(3):437–438
Comtois R, Robert F, Hardy J,: Immunoradiometric assays may miss high prolactin levels Ann Intern Med 1993, 119(2):173
Papik K, Molnar B, Fedorcsak P, Schaefer R, Lang F, Sreter L, Feher J, Tulassay Z,: Automated prozone effect detection in ferritin homogeneous immunoassays using neural network classifiers Clin Chem Lab Med : CCLM/FESCC 1999, 37(4):471–476
Garcia-Webb P, Watson F, Whiteside N,: High-dose“hook”effect in measurement of somatotropin by two-site immunoradiometric assay Clin Chem 1986, 32(11):2102
Sapin R, Schlienger J,: [Thyroglobulin assay ambiguities] Annales de Biologie Clinique 1998, 56(1):41–47
Ooi D, Escares E,: “High-dose hook effect”in IRMA–Count PSA assay of prostate-specific antigen Clin Chem 1991, 37(5):771–772
St-Jean E, Blain F, Comtois R,: High prolactin levels may be missed by immunoradiometric assay in patients with macroprolactinomas Clin Endocrinol 1996, 44(3):305–309
Mendes ABV VJ, Kasamatu T,Oliveira JHA, Abucham J: Falsely low prolactin values in hyperprolactinemic patients due to high dose hook effect. Proceedings of the 79th Annual Meeting of the Endocrine Society, Abstract P1–17 1997
Unnikrishnan A, Rajaratnam S, Seshadri M, Kanagasapabathy A, Stephen D,: The ‘hook effect’ on serum prolactin estimation in a patient with macroprolactinoma Neurol India 2001, 49(1):78–80
Butch A,: Dilution protocols for detection of hook effects/prozone phenomenonClin Chem (Washington, DC, United States) 2000, 46(10):1719–1721
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Fleseriu, M., Lee, M., Pineyro, M.M. et al. Giant invasive pituitary prolactinoma with falsely low serum prolactin: the significance of ‘hook effect’. J Neurooncol 79, 41–43 (2006). https://doi.org/10.1007/s11060-005-9108-7
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DOI: https://doi.org/10.1007/s11060-005-9108-7