Endocrinology and Metabolism

Original Articles

High-Dose Hook Effect in Patients with Macroprolactinoma.: Sung Yeon Kim, Chul Gu Park, Young Ju Choi, Eui Sil Hong, Sang Wan Kim, Chan Soo Shin, Hak Chul Jang, Seong Yeon Kim, Bo Youn Cho, Hong Kyu Lee; J Korean Endocr Soc. 2005;20(2):148-153. Published online April 1, 2005; DOI: https://doi.org/10.3803/jkes.2005.20.2.148

2,696 View
24 Download
1 Crossref

BACKGROUND
Large amounts of antigen may produce false low values on immunoradiometric assays due to the so-called high-dose hook effect. The physicians' awareness of the possibility of the "high-dose hook effect" will prevent preoperative misdiagnosis. The study was designed to identify the frequency and clinical features of patients with pituitary macroadenomas in whom a high-dose PRL hook effect was documented. METHODS: Our retrospective study involved 42 patients with non-functioning pituitary adenomas (tumor diameter >30mm) who underwent transsphenoidal microsurgery from between Jan 1999 to Aug 2004, and 6 patients with non-functioning pituitary adenoma(tumor diameter>30mm) were selected for prospective study from Sep 2003 to Feb 2004. Our retrospective study also involved 13 patients with macroprolactinoma for the comparison of the clinical features. RESULTS: 1) The presence of a high-dose hook effect was retrospectively suggested when the PRL levels increased in 4 out of the 42 patients with non- functioning adenomas(tumor diameter >30mm) after surgery. Post-operative immunohistochemical staining of their pituitary specimens revealed the tumors to be prolactinoma. 2) Prospectively, dilution testing of the specimens obtained before surgery was done in the 6 patients, and one patient presented with a case of the hook effect. The patient's prolactin level was measured at 53.1ng/mL before dilution and this was increased up to 22,600ng/mL upon the 1:1000 dilution. 3) Conclusively, the hook effect was seen in 5 of the 48 patients(10.4%) with non-functioning pituitary adenoma(tumor diameter >30mm) 4) Compared with other 2 patient groups(the macroprolactinoma(N=13) group, and the non-functioning pituitary tumor(N=43) group), the high-dose PRL hook effect is more likely to be observed in male patients with large pituitary tumors. CONCLUSION: In order to avoid the high-dose hook effect, PRL should be assayed at 1:100~1:200 or even higher dilutions of serum from all patients(and especially the male patients) with large pituitary tumors

Citations

Citations to this article as recorded by

Multiple Endocrine Neoplasia Type 1 Presenting with an Invasive Giant Prolactinoma
Jinhoon Cha, Jin Seo Kim, Jung Suk Han, Yeon Won Park, Min Joo Kim, Yun Hyi Ku, Hong Il Kim
The Korean Journal of Medicine.2016; 91(3): 300. CrossRef

Influence of Anti-thyroglobulin Antibody on the Measurement of Thyroglobulin using the Immunoradiometric Assay.: Byeong Cheol Ahn, Jin Ho Bae, Shin Young Jeong, Ho Yong Park, Jung Guk Kim, Sung Woo Ha, Jaetae Lee, Bo Wan Kim, Kyu Bo Lee; J Korean Endocr Soc. 2004;19(1):42-47. Published online February 1, 2004

1,653 View
24 Download

Abstract PDF: BACKGROUND
Serum thyroglobulin(Tg) is a valuable and sensitive tool needed in the follow-up of patients with differentiated thyroid cancer(DTC), but antithyroglobulin antibody(Anti-Tg), common in patients with DTC, can interfere with the assay for Tg. In this study, we evaluated the influence of Anti-Tg on the measurement of Tg using the immunoradiometric assay(IRMA). METHODS: In using ELSA-hTg in vivo test(CIS international, Schering, France), a solid phase two-site IRMA was used to measure Tg(23.5ng/mL, 62.5ng/mL) under the absence or presence of three concentrations of Anti-Tg(25U/mL, 50U/mL, 100U/mL). We also performed Tg measurement using patients serum that was mixed with patients serum containing high Anti-Tg. ANOVA and Scheffe tests were performed to evaluate the effect of Anti-Tg on Tg IRMA, and an inverse regression was made to calculate the level of Tg from measured Tg and used Anti-Tg levels and also to assess the degree of effect of anti-Tg on Tg IRMA. RESULTS: In measuring Tg using the standard solution, the presence of Anti-Tg resulted in a falsely suppressed Tg value. The IRMAs for 23.5ng/mL of the standard Tg solution resulted in 24.5+/-.1 ng/mL under no Anti-Tg, 11.8+/-.4ng/mL under 25U/mL of Anti-Tg, 7.7+/-.1ng/mL under 50U/mL of Anti-Tg, and 4.5+/-.4ng/mL under 100U/mL of Anti-Tg. IRMAs 62.5ng/mL of the standard Tg solution resulted in 65.9+/-.7ng/mL under no Anti-Tg, 36.3+/-.2ng/mL under 25U/mL of Anti-Tg, 23.7+/-.7ng/mL under 50U/mL of Anti-Tg, and 14.0+/-.0ng/mL under 100U/mL of Anti-Tg. (ANOVA test, p=0.000). The degree of suppression of the measured Tg value was positively correlated with the Anti-Tg level (Quadratic model regression, Sig T=0.000). The presence of Anti-Tg also resulted in a falsely suppressed Tg value for the Tg measurement using patient's serum. CONCLUSION: The presence of Anti-Tg could consist of the use of Tg as a tumor, therefore Anti-Tg should be measured in all patients diagnosed with DTC. The interpretation of the Tg level must be performed with extreme caution in patients with Anti-Tg.

First
Prev
Page of 1
Next
Last

Search