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Prolactin hook effect dilution. 5, 45 +/- 6, and 53 +/- 3 yr, for the patients with the hook effect, macroprolactinoma and non-functioning adenoma Jan 5, 2022 · In order to avoid unnecessary surgery (treatment of choice for nonfunctioning tumors), prolactin assays with serum dilution are recommended in patients with macroadenomas who may harbor a prolactinomas . This assay should demonstrate no high-dose hook effect at prolactin concentrations up to approximately Jan 11, 2015 · [Show full abstract] prolactin level, dilution of samples need to be performed to eliminate a possible high dose hook (HDH) effect. Conclusion: Clinicians should be aware of this laboratory phenomenon when evaluating large pituitary or parasellar masses. This assay should demonstrate no high-dose hook effect at prolactin concentrations up to approximately The immunoradiometric PRL assay must be performed with serum dilution in order to overcome the high-dose PRL hook effect in all new patients with pituitary macroadenomas who may have a prolactinoma. She had been operated 4 times earlier and received Jan 6, 2022 · This “hook effect” is due to saturation of the assay antibodies and prolactin levels should always be remeasured at 1:10 or 1:100 dilution in patients with large macroadenomas and normal to modestly elevated prolactin levels . It is an immunologic phenomenon whereby the effectiveness of antibodies to form immune complexes can be impaired when concentrations of an antibody or an antigen are very high. Feb 21, 2023 · 5) Analysis for the hook effect, if suspected, by serial dilution prolactin testing (see above). Some immunoassays do not support sample dilution because of the matrix effect or because they “resist” dilution (e. Jan 6, 2022 · This “hook effect” is due to saturation of the assay antibodies and prolactin levels should always be remeasured at 1:10 or 1:100 dilution in patients with large macroadenomas and normal to modestly elevated prolactin levels . The hook effect occurs in very high levels of prolactin; however, false low levels can also happen in normal levels of the hormone. Feb 1, 2011 · 1. The hook effect should be excluded in patients with prolactin levels less than 200 ng/mL and macroadenomas. Methods: In the current study, implementation of this guideline One tested assay was sensitive to the high-dose hook effect leading to a falsely lower prolactin concentration when measuring native serum (150 µg/L compared to 17,900 µg/L after dilution). 3. 17,22-24 The last method is a computerized kinetic rate analysis in order to establish the need for dilution. Sometimes prolactin levels are elevated due to increased amounts of macroprolactin. Our study demonstrates about at least one-fifth of hyperprolactinemic patients have misdiagnosis from the presence of The high-dose hook effect can be averted by a change of the sample antigen to reagent antibody ratio either by assay reformulation or dilution of the sample. It is identified by re-measuring the prolactin level after performing a serum dilution. Marshfield Clinic Public WebSite Search Test Code May 6, 2020 · Errors in PRL measurement from falsely lowered levels or hook effect and falsely elevated levels or macroprolactinemia result in unnecessary investigation and inappropriate treatment in hyperprolactinemic patients [1,9]. prolactin ; prostate-specific antigen Doctors can detect the hook effect if the 100-fold dilution sample gives a higher result than May 3, 2021 · The best method to avoid the “hook effect” and to correctly interpret prolactin values would be to obtain prolactin levels in appropriately diluted serum specimens (10-100-fold dilution of the sample). For example, a prolactin concentration of 1500 mU/L increased to 950,000 mU/L when dilutions of the sample were reassayed. 1. In summary, the Hook effect is a phenomenon that gives falsely low results in the presence of excess amounts of analyte. Dilution reduces the concentration of prolactin, thus enabling accurate measurement. Sep 27, 2022 · The hook effect is responsible for the discrepancy between tumor size and PRL levels, which generally requires a further diagnostic step based on serum sample dilution . Three results will be reported as follows. 22 Hook effect in prolactin assays is uncommon, but can lead to incorrect diagnosis and management of The high-dose hook effect is mentioned in most recent articles discussing prolactin assay and management of pituitary prolactin adenomas [1-3]. Apr 28, 2018 · The hook effect is a cause for discrepancy between prolactin level and the size of the adenoma. 1. In all patients assay was performed after serum dilution, and only in patients with the hook effect the median PRL levels increased significantly to 5795. 25592 Hook Effect Prolactin Marshfield Lab Public WebSite. 7 ng/mL 10 years and older 2. e rW eport this phenomenon in a patient with a large macroprolactinoma. Quantifying prolactin in serum specimens where the high-dose hook effect is suspected (eg, presence of pituitary tumor with symptoms of prolactinoma, and lower than expected serum prolactin concentration) A pituitary adenoma should be identified by imaging studies prior to ordering this test. ARUP:0020724. If no high-dose hook effect is observed, the following report comment will be included with the prolactin result: 10-, 100-, and 400-fold dilutions produced results consistent with the absence of high-dose hook effect. 1,2 The 100-fold dilution will overcome a potential hook effect and can help to distinguish between a large prolactinoma and a large nonfunctioning Jul 1, 2002 · Both prolactin samples demonstrated the hook effect. Jul 1, 2002 · The hook effect was confirmed when prolactin levels significantly increased after dilution testing of the original serum sample. 21 The third is to dilute the sample, this seems to be the preferred one for its efficacy and simplicity. The hook effect may be unmasked by repeating PRL measurement after a 1:100 serum sample dilution. This will lead to appropriate immune complex formations and increase the sensitivity and specificity of the prolactin assay. Sep 1, 2010 · Hook effect needs to be suspected in every patient with a giant pituitary or parasellar mass and serum prolactin <200 ng/ml. This test is intended for patients with prolactin-secreting macroadenomas, where a high-dose hook effect is a consideration. This could be an orienting assay and an adapted diluent must be used. Reporting • Prolactin results should be interpreted in relation to gender-specific reference intervals. However, articles describing case reports or series of high-dose hook effects in prolactin assay are mostly old or poorly documented [1,7-13]. Interpretation of serum prolactin concentration between 20 and 200 ng/mL in the presence of macroadenoma due to hook effects should be done with caution. 5, 45 +/- 6, and 53 +/- 3 yr, for the patients with the hook effect, macroprolactinoma and non-functioning adenoma Sep 1, 2010 · Europe PMC is an archive of life sciences journal literature. The high-dose hook effect still exists in a very small minority of prolactin assays. In suspected cases of the hook effect, healthcare providers may request a dilution study or employ alternate In all patients assay was performed after serum dilution, and only in patients with the hook effect the median PRL levels increased significantly to 5795. Discover the world's The high-dose hook eect is referred to in most recent papers and book chapters that discuss prolactin assays and the management of prolactin-secreting pituitary adenomas [5–8]. The following years a series of cases was published on the high dose hook effect in patients with macroprolactinomas (1, 2, 5-11), in which dilution of samples was most often advocated as the solution to this effect. The secretion rate of prolactin is about 200 to 536 mcg/day/meter square[1] and the half-life is 25 to 50 minutes. prolactin) was 120 ng/mL, then 1:1 dilution of the specimen should produce a value of 60 ng/mL; but if the observed value was 90 ng/mL (which was significantly higher than the expected value), the Test Components. The mean age at diagnosis was 38 +/- 6. 2 ng/mL Note: This test is intended for patients with prolactin -secreting macroadenomas, where a high dose hook effect is a consideration. 8-29. macroprolactinomas and the hook effect adeno mas, respectively. Falsely low PRL levels may result from the so-called "hook effect," which should be considered in all cases of large (≥3 cm) pituitary adenomas associated with normal or mildly elevated PRL levels (≤250 ng/mL). Jul 1, 2002 · When the hook effect is suspected, dilution testing of prolactin samples may prevent incorrect diagnosis and unnecessary surgical intervention in patients with prolactinomas. A lactogenic effect from injecting anterior pituitary extracts into castrated virgin rabbits was first demonstrated in 1928 by Stricher and Greuter. 2 Since that time prolactin has been shown to have more than 300 actions across reproduction Sep 29, 2023 · The hook effect occurs in very high levels of prolactin; however, false low levels can also happen in normal levels of the hormone. Without upfront dilutions, hook effect was observed in samples with ferritin concentrations as low as 86,028 µg/L. Conclusion. Both prolactin samples demonstrated the hook effect. 0 (2097. . Macroprolactin is an isoform of PRL with a greater molecular weight but reduced biological activity, occurring in about 20% of cases and associated with asymptomatic Jul 6, 2022 · The objective of our study was to evaluate if the high-dose hook effect remains relevant in current practice, when using currently available assays. In this article, we focus these two pitfalls in the laboratorial diagnosis of the hyperprolactinemia, remembering that they could occur and interfere Jul 6, 2022 · One tested assay was sensitive to the high-dose hook effect leading to a falsely lower prolactin concentration when measuring native serum (150µg/L compared to 17,900µg/L after dilution). Dilution testing can counteract this assay phenomenon. 005) than 54 nonfunctioning adenomas and 11 macroprolactinomas not demonstrating the hook effect. As previously, described (3) a dilution for prolactin Jan 1, 2022 · Serial dilution of the sample is the simplest approach when interference is suspected (or for a hook effect). Jul 12, 2011 · Two-site immunometric assays, particularly those in which signal and capture antibody are added simultaneously, are vulnerable to the high-dose hook effect at very high analyte concentration. Clinical Presentation and Intervention: A 45-year-old Feb 2, 2018 · Results. Jul 31, 2023 · Patients can have very high prolactin levels; however, when measured, they can be reported as falsely low due to a phenomenon called the “Hook effect. 64,65 Free analyte and bound analyte compete for the limited number of solid-phase antibody-binding sites, yielding inappropriately low results which may Patients who show neither a decrease in prolactin levels nor tumor shrinkage might require additional therapeutic measures. where a high-dose hook effect is a consideration. The best way to eliminate the hook effect is serial dilution. 0. Serum or Plasma. Importantly, these two distinct issues have often been confused, especially in prolactin (PRL) immunoassays, where inappropriately low levels of prolactin A high-dose hook effect is ruled out if the result generated from the diluted sample (after correcting for dilution) is not significantly greater than the result obtain from the undiluted sample. In this patient, the correct estimate of serum prolactin (PRL) was obtained only after appropriate dilution of serum. Other suggested remedies for the hook effect include the use of an excess antibody, a cumbersome two-step procedure, and the use of a computer to Jul 24, 2023 · Prolactin hormone is exclusively synthesized and secreted from lactotrophs of the anterior pituitary gland. Sample will be analyzed undiluted (1:1), as well as at 1:10, 1:100 and 1:1000 dilutions. Assaying a diluted serum will usually unmask this phenomenon and allow Aug 1, 2022 · One tested assay was sensitive to the high-dose hook effect leading to a falsely lower prolactin concentration when measuring native serum (150 µg/L compared to 17,900 µg/L after dilution Oct 1, 2000 · It is suggested that patients with high dose PRL hook effect are generally younger, more frequently males with very large pituitary adenomas (grade III–IV according to Hardy), and it is necessary, whenever performing IRMA for serum prolactin measurement, to dilute samples routinely (1:1 and 1:10 dilutions) in every patient with pituitsary tumor. Objectives: To describe a patient who was misdiagnosed as having a nonfunctional pituitary tumor due to the hook effect on prolactin measurements. In patients where a discrepancy between pituitary tumor size and prolactin elevation is observed, a test for false-low serum prolactin (hook effect) should be performed by serial dilution. The Hook effect only exists in one-step heterogeneous immunoassays. Despite the efforts, the Hook effect still exists in modern assays. The hook effect refers to the prozone phenomenon, also known as antibody excess or the Postzone phenomenon, also known as antigen excess. Specimen Type. We report this phenomenon in a patient with a large macroprolactinoma. Hook effect. Prolactin is metabolized by the liver (75%) and the kidney (25%). Pregnancy, lactation, and the administration of oral contraceptives can increase prolactin concentrations. However, articles describing case reports or series of high-dose hook eects in the prolactin assay are mostly old or poorly-documented [6, 9–15]. The basal level of prolactin in women averages 13 ng/ml and in men, it averages 5 ng/ml. When there is a discrepancy between a very large pituitary tumor and a mildly elevated prolactin level, we recommend serial dilution of serum samples to eliminate an artifact that can occur with some immunoradiometric assays leading to a falsely low prolactin value (“hook effect”) (1|⊕⊕⊕⊕). May 1, 2004 · Hook effect needs to be suspected in every patient with a giant pituitary or parasellar mass and serum prolactin <200 ng/ml and Assaying a diluted serum will usually unmask this phenomenon and allow accurate diagnosis and management. Serum from a patient with a giant macroprolactinoma was assayed using all of the available prolactin assays in France in 2020, using native serum and after dilution. This is called the ‘high dose hook effect’. Hook Effect • If an unexpectedly low/normal prolactin result is obtained on a patient with a prolactinoma, serial dilution of the serum sample can aid in identifying the hook effect. HEPRL: Hook Effect Prolactin (Presence or Absence of Hook Effect) PROLAC: Prolactin (Final Prolactin result reported) PRLDIL: Hook Effect Final Dilution. Dopamine agonist therapy was initiated, and the prolactin level and size of the tumor decreased substantially. See PLPMA / Prolactin, Pituitary Macroadenoma, Serum. Clinical Presentation and Intervention: A 45-year-old female was admitted with visual disturbances, panhypopituitarism and central diabetes insipidus due to pituitary tumor recurrence. This is called the 'high dose hook effect'. Conclusion Introduction. , free thyroid hormone assays) [ 175 ]. Although few changes in the principles of immunoassays have Mar 20, 2019 · The hook effect is an assay artifact caused by an extremely high level of PRL, which saturates the detecting antibody used in the PRL assay, thus resulting in a falsely low reported value [16, 99, 100]. Sep 5, 2023 · The hook effect is rarely encountered in current assays, but should be considered when prolactin level is only mildly elevated and clinical suspicion for a macroprolactinoma is high 61. The 4 macroprolactinomas demonstrating the hook effect were significantly larger ( P < 0. 1-17. When the hook effect is suspected, dilution testing of prolactin samples may prevent incorrect diagnosis and unnecessary surgical intervention in patients with prolactinomas. The evolution of assay methods may lead to new assays that remain Feb 1, 2008 · Accurate prolactin values should be obtained after serum sample dilution in order to overcome the "hook effect" due to very high antigen levels [12, 13]. Pregnancy, lactation, and May 7, 2021 · Furthermore, the “hook effect” should be considered in patients with normal or mildly elevated prolactin concentration and large pituitary adenomas (≥ 3 cm), particularly in laboratories Jul 1, 2002 · Both prolactin samples demonstrated the hook effect. Evidence For prolactinomas, serum prolactin levels generally Aug 6, 2008 · Abstract. The Hook effect can be easily detected and corrected by serial dilution of a sample. 92 To detect a high dose hook effect in Tg assays, it is Epic Test Code LAB4939 Prolactin, Dilution Study Additional Codes. Causes of hyperprolactinemia. The hook effect most commonly occurs when excess antigen (for example, prolactin) is present during testing. With upfront dilutions, samples with ferritin concentrations as high as 126,050 µg/L yielded values greater than the measurement interval and would have been diluted until an accurate value was obtained. A Interpretation. Thus, despite the accuracy and specificity Oct 29, 2023 · To mitigate the hook effect and obtain accurate prolactin measurements, dilution of the blood sample is recommended. 22,000 ng/mL. 2-12722. 1 Then in 1933 Riddle and colleagues purified the responsible hormone and named it prolactin in recognition of its major role in lactation. Although there have Oct 10, 2017 · The hook effect or the prozone effect is a type of interference which plagues certain immunoassays and nephelometric assays, resulting in false negatives or inaccurately low results . Sep 1, 2010 · Firstly, the 'hook' effect that occurs when a very high serum prolactin level (>5000 mg/L) saturates both the capture and signal antibodies used in measurement assays preventing the binding of the In patients where a discrepancy between pituitary tumor size and prolactin elevation is observed, a test for false-low serum prolactin (hook effect) should be performed by serial dilution. g. Prolactin Age Male Female, nonpregnant 1-9 years 2. Jul 6, 2022 · One tested assay was sensitive to the high-dose hook effect leading to a falsely lower prolactin concentration when measuring native serum (150 µg/L compared to 17,900 µg/L after dilution). in whom the hook effect lead to misdiagnosis of a large macroprolactinoma. To mitigate the hook effect and obtain accurate prolactin measurements, dilution of the blood sample is recommended. ” When there is a suspicion, serial dilution of the serum sample and re-measuring the prolactin levels will be helpful. 2. We suggest that in order to avoid the high dose hook effect, the serum PRL be estimated in appropriate dilution Prolactin, Pituitary Macroadenoma, Serum. We describe a young female patient with giant invasive sellar and suprasellar tumor and modest elevation of prolactin to 165 ng/ml (normal range 3-29). Recent assays do not present hook effect at PRL concentrations as high as 295,000 mIU/L (around 14,750 ng/mL) . The effect can also occur because of antigen excess, when both the capture and detection antibodies become saturated by the high analyte concentration. 2) micrograms/l. We suggest that in order to avoid the high dose hook effect, the serum PRL be estimated pituitary tumor and a mildly elevated prolactin level, we recommend serial dilution of serum samples to eliminate an artifact that can occur with some immunoradiometric assays leading to a falsely low prolactin value (“hook ef-fect”) (1 QQQQ). eliminate the hook effect. In all patients assay was per formed after serum dilution, and only in patients with the hook effect the median PRL levels in-INTRODUCTION In the last few years it has been increasingly rec ognized that immunoradiometric assay (IRMA) for Aug 1, 2008 · 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. 7 ng/mL 2. For example, if the hook effect is present and the original value of an analyte (e. The upper normal Jan 11, 2015 · Among the potential flaws involving immunoassays are the hook effect, also known as prozone phenomenon, and the reporting of concentrations outside the dynamic (linear) range of the assay. 6) Anterior pituitary panel: Testosterone, estradiol, free thyroxine ( FT 4 ), luteinizing hormone ( LH ), follicle-stimulating hormone ( FSH ), adrenocorticotropic hormone ( ACTH ), cortisol, insulin-like growth factor 1 ( IGF-1 ; for GH excess Oct 1, 2015 · The Endocrine Society’s Clinical Guideline “Diagnosis and Treatment of Hyperpro lactinemia” (2011) recommends that in case of discrepancy between a very large pituitary tumor and a mildly elevated prolactin level, dilution of samples need to be performed to eliminate a possible high dose hook (HDH) effect. Feb 21, 2020 · The hook effect in pregnancy is a false-negative result. em cs xw wc dw wl ua ry mh xh