scholarly journals Specificity and Clinical Utility of Methods for the Detection of Macroprolactin

2006 ◽  
Vol 52 (7) ◽  
pp. 1366-1372 ◽  
Author(s):  
Lucille Kavanagh ◽  
T Joseph McKenna ◽  
Michael N Fahie-Wilson ◽  
James Gibney ◽  
Thomas P Smith
Keyword(s):  
Polyethylene Glycol ◽  
Clinical Utility ◽  
Protein A ◽  
Gel Filtration ◽  
Protein G ◽  
Serum Concentrations ◽  
Gel Filtration Chromatography ◽  
Common Cause ◽  
Choice Alternative ◽  
First Choice

Abstract Background: Increased serum concentrations of macroprolactin are a relatively common cause of misdiagnosis and mismanagement of hyperprolactinemic patients. Methods: We studied sera from a cohort of 42 patients whose biochemical hyperprolactinemia was explained entirely by macroprolactin. Using 5 pretreatments, polyethylene glycol (PEG), protein A (PA), protein G (PG), anti-human IgG (anti-hIgG), and ultrafiltration (UF), to deplete macroprolactin from sera before immunoassay, we compared residual prolactin concentrations with monomer concentrations obtained by gel-filtration chromatography (GFC). A monomeric prolactin standard was used to assess recovery and specificity of the pretreatment procedures. Results: Residual prolactin concentrations in all pretreated sera differed significantly (P <0.001) from monomeric concentrations obtained after GFC. PEG underestimated (mean, 75%), whereas PA, PG, anti-hIgG, and UF overestimated (means, 178%, 151%, 178%, and 112%, respectively) the amount of monomer present. Of the 5 methods examined, PEG correlated best with GFC (r = 0.80) followed by PG (r = 0.78), PA (r = 0.72), anti-hIgG (r = 0.70), and UF (r = 0.61). After UF or pretreatment with anti-hIgG or PEG, recovery of monomeric prolactin standard was low: 60%, 85%, and 77% respectively. In contrast, pretreatment with PA or PG gave almost quantitative recovery. Conclusions: None of the methods examined yielded results identical to the GFC method. PEG pretreatment yielded results that correlated best and is recommended as the first-choice alternative to GFC.

scholarly journals Discrepancy between Cardiac Troponin Assays Due to Endogenous Antibodies

2020 ◽  
Vol 66 (3) ◽  
pp. 445-454 ◽  
Author(s):  
Leo Lam ◽  
Lisa Aspin ◽  
Robert Campbell Heron ◽  
Leah Ha ◽  
Campbell Kyle
Keyword(s):  
Regression Analysis ◽  
Polyethylene Glycol ◽  
Cardiac Troponin ◽  
Protein A ◽  
Gel Filtration ◽  
Interquartile Range ◽  
Clinical Use ◽  
Gel Filtration Chromatography ◽  
Polyethylene Glycol Precipitation

Abstract Background Despite well-described analytical effects of autoantibodies against cardiac troponin (cTn) I on experimental assays, no study has systematically examined their impact on cTn assays in clinical use. We determined the effects of endogenous antibodies on 5 different cTnI assays and a cTnT assay. Methods cTn was measured by 6 methods: Siemens hs-cTnI Centaur, Siemens hs-cTnI Vista, Abbott hs-cTnI Architect, Beckman hs-cTnI Access, Beckman cTnI Access, and Roche hs-cTnT Elecsys. Measurements were repeated on 5 assays (all except Siemens hs-cTnI Vista) following immunoglobulin depletion by incubation with protein A. Low recovery of cTnI (<40%) following immunoglobulin depletion was considered positive for macro-cTnI. Protein A findings were validated by gel filtration chromatography and polyethylene glycol precipitation. Results In a sample of 223 specimens selected from a community laboratory that uses the Siemens hs-cTnI Centaur assay and from which cTn was requested, 76% of samples demonstrated increased cTnI (median, 88 ng/L; interquartile range, 62–204 ng/L). Macro-cTnI was observed in 123 (55%) of the 223 specimens. Comparisons of cTnI assays markedly improved once patients with macro-cTnI were removed. Passing-Bablok regression analysis between hs-cTnI assays demonstrated different slopes for patients with and without macro-cTnI. In patients with macro-cTnI, 89 (72%) showed no effect on the recovery of cTnT, whereas 34 (28%) had reduced recovery of cTnT. The proportion of results above the manufacturers' 99th percentile varied with the cTn assay and macro-cTnI status. Conclusion We suggest that the observed discrepancy between hs-cTnI assays may be attributed in part to the presence of macro-cTnI.

Screening for macroamylase in a community hospital.

1984 ◽  
Vol 30 (5) ◽  
pp. 741-742 ◽  
Author(s):  
C A Isham ◽  
N A Ridgeway ◽  
R Hedrick ◽  
J C Cate
Keyword(s):  
Polyethylene Glycol ◽  
Community Hospital ◽  
Serum Amylase ◽  
Gel Filtration ◽  
Screening Procedure ◽  
Gel Filtration Chromatography ◽  
Polyethylene Glycol Precipitation ◽  
Precipitation Test

Abstract We evaluated the polyethylene glycol precipitation test (Gastroenterology 83: 378-382, 1982), looking for macroamylase in the serum of 66 patients whose values for serum amylase were above normal. Three patients (4.5%) were identified by this method as having macroamylase , and this was confirmed by gel-filtration chromatography and electrophoresis. We find this to be the test of choice as a screening procedure for macroamylasemia because of its speed, simplicity, and apparent reliability. Diagnosis of macroamylasemia is important in preventing needless treatment and investigation for pancreatitis.

A possible cause of the variable detectability of macroprolactin by different immunoassay systems

2016 ◽  
Vol 54 (4) ◽  
Author(s):  
Naoki Hattori ◽  
Kohzo Aisaka ◽  
Akira Shimatsu
Keyword(s):  
Polyethylene Glycol ◽  
Gel Filtration ◽  
Protein G ◽  
Normal Range ◽  
Serum Samples ◽  
Chemiluminescence Immunoassay ◽  
Factors Influencing ◽  
Group 2 ◽  
Possible Cause ◽  
Group 1

AbstractMacroprolactinaemia is a major cause of hyperprolactinaemia. The detectability of macroprolactin varies widely among different immunoassay systems, but the causes are not fully known. This study aimed to identify the factors influencing the detectability of macroprolactin by immunoassay systems.The study included 1544 patients who visited an obstetric and gynaecological hospital. Macroprolactinaemia was screened using the polyethylene glycol (PEG) method and confirmed using gel filtration chromatography and the protein G method. The prolactin (PRL) values determined by enzyme immunoassay (EIA) were compared with those of a chemiluminescence immunoassay system (Centaur) that is known to cross-react the least with macroprolactin.Macroprolactinaemia was found in 62 of 1544 patients (4.02%) who visited an obstetric and gynaecological hospital. The ratio of EIA-determined total PRL to free PRL in the supernatant after PEG precipitation was significantly elevated in all 62 serum samples with macroprolactin compared to those in 1482 serum samples without macroprolactin. In contrast, the ratio of Centaur-determined total PRL to free PRL was significantly elevated in 32 serum samples (group 1) and was within the normal range in 30 (group 2) of 62 serum samples with macroprolactin. The prevalence of non-IgG-type macroprolactin was significantly higher in group 1 than in group 2. Centaur diagnosed hyperprolactinaemia less frequently than EIA (n=2 vs. 16) in 62 patients with macroprolactinaemia. Those two hyperprolactinaemic patients diagnosed by Centaur had non-IgG-type macroprolactin.Macroprolactinaemia was present in 4% of patients visiting an obstetric and gynaecological hospital. The nature of macroprolactin (IgG-type or non-IgG-type) may partly explain why macroprolactin detectability varies among different immunoassay systems.

scholarly journals Macroprolactinaemia: Contribution to Hyperprolactinaemia in a District General Hospital and Evaluation of a Screening Test Based on Precipitation with Polyethylene Glycol

1997 ◽  
Vol 34 (3) ◽  
pp. 252-258 ◽  
Author(s):  
M N Fahie-Wilson ◽  
S G Soule
Keyword(s):  
Polyethylene Glycol ◽  
Screening Test ◽  
Reference Range ◽  
Gel Filtration ◽  
District General Hospital ◽  
Serum Prolactin ◽  
Common Phenomenon ◽  
Common Cause ◽  
Upper Limit ◽  
Polyethylene Glycol 6000

For a period of 12 months all samples submitted for serum prolactin (PRL) assay and with PRL>700mU/L were examined by gel filtration chromatography. In 17 (25%) of 69 samples we found macroprolactin. The Delfia and Immuno 1 immunoassay systems gave similar PRL results with samples containing macroprolactin whereas the ACS 180 system gave lower results. With the Delfia and Immuno 1 systems samples containing substantial quantities of macroprolactin showed low recovery of PRL after precipitation with polyethylene glycol 6000 (PEG 6000) and this technique can be used as a screening test for macroprolactinaemia. We conclude that macroprolactinaemia is a common phenomenon and, in assays which detect this species, is a common cause of hyperprolactinaemia. Macroprolactinaemia may contribute to the difficulty in establishing an upper limit of the reference range for serum PRL. In our experience, patients with macroprolactinaemia do not exhibit features of the hyperprolactinaemia syndrome and it is important to recognize macroprolactin as the cause of hyperprolactinaemia to avoid unnecessary investigation and treatment.

scholarly journals Frequency of Macroprolactinemia Due to Autoantibodies against Prolactin in Pregnant Women

2001 ◽  
Vol 86 (2) ◽  
pp. 924-929 ◽  
Author(s):  
Dalila Pascoe-Lira ◽  
Genoveva Duran-Reyes ◽  
Iris Contreras-Hernández ◽  
Leticia Manuel-Apolinar ◽  
Francisco Blanco-Favela ◽  
...  
Keyword(s):  
Polyethylene Glycol ◽  
Pregnant Women ◽  
Molecular Mass ◽  
Chromatographic Separation ◽  
Protein A ◽  
Gel Filtration ◽  
Serum Levels ◽  
The Other ◽  
Positive Correlation ◽  
Before And After

The frequency of macroprolactinemia related to the presence of anti-PRL autoantibodies in the serum of 209 healthy women at different stages of pregnancy was studied. Measurements were taken of serum PRL concentrations before and after chromatographic separation (gel filtration and affinity with proteins A and G) and extraction of free PRL with polyethylene glycol (PEG). Sera from 8 of the 209 women (3.8%) were found to have a significantly high proportion of precipitated PRL by PEG (macroprolactinemia); in these patients, gel filtration showed that a substantial amount of big big PRL (molecular mass >100 kDa) was present (19.0–78.2% vs. 3.8–4.9%, P = 0.009 in normal pregnant women with a normal proportion of precipitated PRL by PEG). The presence of macroprolactinemia was attributable to anti-PRL autoantibodies in 5 of the 8 women. Comparison of serum levels of direct and free PRL between women with macroprolactinemia related to anti-PRL autoantibodies and women without macroprolactinemia showed significant differences (direct PRL: 270.2 ± 86.9 vs. 203.4 ± 69.0 μg/L, P = 0.04; and free PRL: 107.0 ± 75.9 vs. 173.3 ± 67.6 μg/L, P = 0.002). On the other hand, there was no difference between women with macroprolactinemia not related to anti-PRL autoantibodies and women with macroprolactinemia caused by anti-PRL autoantibodies, nor was there a difference between women with macroprolactinemia not related to anti-PRL autoantibodies and women without macroprolactinemia. There was a positive correlation between titers of the anti-PRL autoantibody and serum PRL levels (r = 0.82, P = 0.09). The presence of the anti-PRL autoantibody had no relation to the patient’s age, stage of gestation, or number of previous pregnancies. We concluded that the frequency of macroprolactinemia was 3.8% among healthy, pregnant women, which was caused by a anti-PRL autoantibodies in 62.5% of the cases. The autoantibodies were found in the bloodstream, forming a PRL-IgG complex, in accordance with the following observations: 1) immunoreactive PRL on gel filtration was eluted in the fractions corresponding to the molecular mass of IgG (150 kDa); 2) a significantly high proportion of immunoreactive PRL was retained on an affinity gel for IgG (proteins A and G); and 3) a significantly high proportion of serum PRL bound to IgG was precipitated by protein A. There was a positive correlation between titers of anti-PRL autoantibodies and serum PRL levels. Serum levels of total PRL were higher, and serum levels of free PRL were lower, in pregnant women with anti-PRL autoantibodies than in pregnant women without macroprolactinemia.

scholarly journals Variability in the detection of macro TSH in different immunoassay systems

2016 ◽  
Vol 174 (1) ◽  
pp. 9-15 ◽  
Author(s):  
Naoki Hattori ◽  
Takashi Ishihara ◽  
Akira Shimatsu
Keyword(s):  
Hormone Replacement Therapy ◽  
Polyethylene Glycol ◽  
Subclinical Hypothyroidism ◽  
Hormone Replacement ◽  
Elevated Serum ◽  
Gel Filtration ◽  
Cross Reactivity ◽  
Serum Samples ◽  
Gel Filtration Chromatography ◽  
Serum Tsh

DesignMacro TSH is a large molecular-sized TSH that is mostly a complex of TSH and IgG. Patients with macro TSH have elevated serum TSH and normal free thyroxine levels, mimicking subclinical hypothyroidism. The aim of this study was to clarify the degree of cross-reactivity of macro TSH to different commercial immunoassay systems.MethodsScreening for macro TSH was done using a polyethylene glycol (PEG) method and confirmed with gel filtration chromatography in serum samples from 1901 patients with subclinical hypothyroidism. Interference due to human anti-mouse antibodies (HAMA) was examined using HAMA blockers. TSH was measured with an enzyme immunoassay for the analysis of macro TSH. Serum TSH values in patients with macro TSH were also determined with the widely used commercial immunoassay platforms Elecsys, Centaur and Architect, and the detectability of macro TSH was compared among them.ResultsGel filtration chromatography was performed with 174 serum samples with PEG-precipitable TSH ratios >75%. Twenty serum samples were found to contain large molecular-sized TSH, five of which were due to interference by HAMA. The prevalence of macro TSH was eventually 0.79% (15/1901). Commercial immunoassay systems variably recognized macro TSH. The Architect TSH immunoassay platform was the least reactive to macro TSH, but still recognized it in 60% of macro TSH-containing serum samples.ConclusionsThere were no commercial TSH immunoassay platforms that did not cross-react with macro TSH. Screening for macro TSH should be performed before hormone replacement therapy is initiated for subclinical hypothyroidism.

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