Diagnosis of insulin autoimmune syndrome using polyethylene glycol precipitation and gel filtration chromatography withex vivoinsulin exchange

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.

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Discrepancy between Cardiac Troponin Assays Due to Endogenous Antibodies

Clinical Chemistry ◽

10.1093/clinchem/hvz032 ◽

2020 ◽

Vol 66 (3) ◽

pp. 445-454 ◽

Cited By ~ 3

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.

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[43] Isolation of soluble immune complexes from human serum: Combined use of polyethylene glycol precipitation, gel filtration, and affinity chromatography on protein A-sepharose

Methods in Enzymology - Immunochemical Techniques - Part C ◽

10.1016/0076-6879(81)74045-x ◽

1981 ◽

pp. 644-663 ◽

Cited By ~ 9

Author(s):

Gabriel Virella ◽

J. Michael Kilpatrick ◽

Francoise Chenais ◽

H. Hugh Fudenberg

Keyword(s):

Polyethylene Glycol ◽

Affinity Chromatography ◽

Human Serum ◽

Immune Complexes ◽

Protein A ◽

Gel Filtration ◽

Combined Use ◽

Soluble Immune Complexes ◽

Polyethylene Glycol Precipitation

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Macro-alkaline phosphatase due to IgG κ complex: demonstration with polyethylene glycol precipitation and immunofixation

Annals of Clinical Biochemistry International Journal of Laboratory Medicine ◽

10.1258/000456302320314584 ◽

2002 ◽

Vol 39 (5) ◽

pp. 523-525 ◽

Cited By ~ 5

Author(s):

MC Owen ◽

LS Pike ◽

PM George ◽

ML Barclay ◽

CM Florkowski

Keyword(s):

Alkaline Phosphatase ◽

Polyethylene Glycol ◽

Gel Filtration ◽

Light Chains ◽

Elevated Plasma ◽

Plasma Alkaline Phosphatase ◽

Polyethylene Glycol Precipitation

An otherwise unexplained, persistently elevated plasma alkaline phosphatase concentration in a 71-year-old woman was found to be attributable to the presence of macro-alkaline phosphatase using polyethylene glycol precipitation. Gel filtration showed two high MW peaks with masses of about 330 kDa and 560 kDa. The alkaline phosphatase (ALP) complex was characterized by immunoelectrophoresis as a complex with IgG with κ light chains.

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Variability in the detection of macro TSH in different immunoassay systems

Acta Endocrinologica ◽

10.1530/eje-15-0883 ◽

2016 ◽

Vol 174 (1) ◽

pp. 9-15 ◽

Cited By ~ 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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Specificity and Clinical Utility of Methods for the Detection of Macroprolactin

Clinical Chemistry ◽

10.1373/clinchem.2005.065854 ◽

2006 ◽

Vol 52 (7) ◽

pp. 1366-1372 ◽

Cited By ~ 60

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.

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