scholarly journals Hypeprolactinemia: still an insidious diagnosis

Endocrine ◽  
2020 ◽  
Author(s):  
Ludovica Aliberti ◽  
Irene Gagliardi ◽  
Romolo M. Dorizzi ◽  
Stefano Pizzicotti ◽  
Marta Bondanelli ◽  
...  
Keyword(s):  
Psychological Stress ◽  
Clinical Picture ◽  
Reference Interval ◽  
Rheumatoid Factors ◽  
Hormone Concentration ◽  
Hook Effect ◽  
Analytical Interference ◽  
Hormonal Evaluation ◽  
Very High ◽  
Endocrinology Clinic

Abstract Hyperprolactinemia can have different causes: physiological, pharmacological, and pathological. When investigating the etiology of hyperprolactinemia, clinicians need to be aware of several conditions leading to misdiagnosis. The most popular pitfalls are: acute physical and psychological stress, macroprolactin, hook effect, even though antibodies interferences and biotine use have to be considered. A 52-year-old woman was referred to Endocrinology clinic for oligomenorrhoea and headache. She worked as a butcher. Hormonal evaluation showed very high PRL (305 ng/ml, reference interval: <24 ng/ml) measured with the ECLIA immunoassay analyzer Elecsys 170. The patient’s pituitary MRI was normal and macroprolactin was normal. Hormonal workup showed LH: 71.5 mU/ml (2–10.9 mU/ml), FSH: 111.4 mU/ml (3.9–8.8 mU/ml), Estradiol: 110.7 pg/mL (27–122 pg/ml). Since an interference was suspected, the sample was sent to another laboratory using a different assay. After antibody blocking tubes treatment (Heterophilic Blocking Tube, Scantibodies) PRL was 28.8 ng/ml (reference interval < 29.2 ng/ml). Analytical interference should be suspected when assay results are not consistent with the clinical picture. Endogenous antibodies (EA) include heterophile, human anti-animal, autoimmune and other nonspecific antibodies, and rheumatoid factors, that have structural similarities and can cross-react with the antibodies employed by the immunoassay, causing hyperprolactinemia misdiagnosis. The patient’s job (butcher), led us to suspect the presence of anti-animal antibodies. Clinicians should also carefully investigate the use of supplements. Biotin can falsely increase hormone concentration in competitive assays. Many clinicians are still not informed about these pitfalls that are not mentioned in some recent reviews on PRL measurement.

scholarly journals Feline plasma adrenocorticotropic hormone: validation of a chemiluminescent assay and concentrations in cats with hypercortisolism, primary hypoadrenocorticism and other diseases

2020 ◽  
pp. 1098612X2092568
Author(s):  
Antonio M Tardo ◽  
Claudia E Reusch ◽  
Sara Galac ◽  
Sofia Fornetti ◽  
Alessandro Tirolo ◽  
...  
Keyword(s):  
Adrenocorticotropic Hormone ◽  
Reference Interval ◽  
Robust Methods ◽  
Hormone Concentration ◽  
Plasma Acth ◽  
Naturally Occurring ◽  
Assay Precision ◽  
Diagnostic Work ◽  
Work Up ◽  
Interassay Precision

Objectives The aims of this study were to validate a commercially available chemiluminescent assay for measurement of feline plasma adrenocorticotropic hormone concentration (ACTH), to determine the normal reference interval (RI) of plasma ACTH in healthy cats, to assess plasma ACTH in cats with naturally occurring hypercortisolism (HC), primary hypoadrenocorticism (PH) and other diseases (OD), and to evaluate the effect of aprotinin on plasma ACTH degradation. Methods Forty healthy cats, 10 with HC, 11 with PH and 30 with OD, were included. The chemiluminescent enzyme immunometric assay was evaluated by measurement of intra-assay precision, interassay precision and linearity. The RI for plasma ACTH in healthy cats was established using robust methods. Plasma ACTH of samples collected with and without aprotinin, stored at 4°C and assayed over a 6-day period, was measured. Results The intra-assay coefficients of variance (CVs) ranged from 2.7% to 4.3% and interassay CVs from 3.3% to 10.7%. Dilution studies showed excellent accuracy (R2 >0.99). The RI for plasma ACTH in healthy cats was 32–370 pg/ml. Plasma ACTH was not significantly different between healthy cats and the OD group. Cats with pituitary-dependent hypercortisolism (PDH) and PH had significantly higher plasma ACTH than the other groups. Plasma ACTH did not show significant differences when samples collected with and without aprotinin were compared. Conclusions and relevance The Immulite chemiluminescent assay is a valid technique for measuring plasma ACTH in cats and the RI of plasma ACTH is quite wide. Owing to the low overlap between healthy or OD cats and cats with HC or PH, the measurement of plasma ACTH appears to be useful and should be included in the diagnostic work-up when HC or PH are suspected. Furthermore, the measurement of plasma ACTH may be an accurate test for differentiating PDH from adrenal-dependent hypercortisolism.

Evaluation of a new free-thyroxin assay.

1981 ◽  
Vol 27 (12) ◽  
pp. 2022-2024 ◽  
Author(s):  
M L Wellby ◽  
L Guthrie ◽  
C P Reilly
Keyword(s):  
Oral Contraceptives ◽  
Reference Interval ◽  
Free T4 ◽  
Single Tube ◽  
High Affinity ◽  
Assay Precision ◽  
Very High ◽  
Interassay Precision ◽  
Better Than

Abstract The Amerlex Free Thyroxin (T4) Radioimmunoassay Kit (Amersham International Ltd.) is a new direct equilibrium radioimmunoassay for free T4 based on an antiserum with very high affinity for T4, and a unique 125I-labeled T4 analog as tracer. It is a very simple single-tube radioimmunoassay, making use of Amerlex particles to separate antibody-bound from free species. Interassay precision (CV) is 3.7% at 13 pmol/L and 2.3% at 30 pmol/L; within-assay precision is 4.2% at 21 pmol/L. The reference interval is 11-22 pmol/L. The assay did not misclassify any patients tested who had untreated myxedema or untreated thyrotoxicosis. The free T4 assay excelled both the free T4 index and the T4/T4-binding globulin ratio in correcting for increased thyroxin-binding globulin from pregnancy, and it was better than the index but not better than the ratio in correcting for increased thyroxin-binding globulin in users of oral contraceptives.

scholarly journals Quantitative nephelometric assay for determining myoglobin evaluated

1990 ◽  
Vol 36 (9) ◽  
pp. 1675-1678 ◽  
Author(s):  
J R Delanghe ◽  
J P Chapelle ◽  
S C Vanderschueren
Keyword(s):  
Reliable Method ◽  
High Dose ◽  
Rheumatoid Factors ◽  
Test Results ◽  
Multiple Forms ◽  
Hook Effect ◽  
Tissue Extracts ◽  
The Mean ◽  
Serum Myoglobin

Abstract A recently introduced automated nephelometric immunoassay involving shell/core particles for determination of myoglobin (Behringwerke) was evaluated with the BNA Nephelometer. Method precision was good: the intra-assay CV varied between 1.5% and 6.1%; with daily calibration, the interassay CV ranged between 1.5% and 7.5%. For usual sample dilutions, the assay response varied linearly with myoglobin concentrations up to 23.1 nmol/L. After automatic dilution by the instrument, concentrations up to 2310 nmol/L could be measured without high-dose "hook" effect. Further manual dilution allowed measurement of myoglobin concentrations up to 26,000 nmol/L. Calibration was stable for at least seven days. We detected no significant interferences from hemoglobin, haptoglobin, bilirubin, iodine-containing contrast media, and rheumatoid factors. Treating lipemic samples with Lipoclean (Behringwerke) decreased test results. Simultaneously drawn serum and plasma samples from the same subject showed no consistent differences in myoglobin concentrations. The mean reference myoglobin concentration was 1.380 (SD 0.82) nmol/L for men and 0.878 (SD 0.45) nmol/L for women. In patients with renal insufficiency, serum creatinine values were moderately related to serum myoglobin values (r = 0.465). Although a commercial radioimmunoassay (Byk-Sangtec) and the nephelometric assay intercorrelated well (r = 0.929), values obtained by nephelometry were significantly lower (P less than 0.05). By both assays, results for heart and skeletal muscle tissue extracts showed no correlation, a finding that suggests the existence of multiple forms of myoglobin in human tissues. We conclude that immunonephelometry is a rapid, practical, and reliable method for measuring myoglobin in serum.

Rapid determination of serum myoglobin with a routine chemistry analyzer

1993 ◽  
Vol 39 (4) ◽  
pp. 653-658 ◽  
Author(s):  
A J Bakker ◽  
D A Boymans ◽  
D Dijkstra ◽  
J P Gorgels ◽  
R Lerk
Keyword(s):  
Predictive Value ◽  
Rapid Determination ◽  
Reference Interval ◽  
High Dose ◽  
Reference Limit ◽  
Hook Effect ◽  
Upper Limit ◽  
Upper Reference Limit ◽  
Serum Myoglobin

Abstract A turbidimetric immunoassay system (Turbitime system, Behringwerke AG) allows rapid determination of myoglobin in serum. We adapted the reagents for this myoglobin assay (Turbiquant myoglobin) for use with a Hitachi 717 analyzer. No high-dose hook effect was observed up to 15,000 micrograms/L. Interassay CVs were 4.6% (mean = 72.0 micrograms/L; n = 9) and 2.5% (mean = 365.6 micrograms/L; n = 11). The calibration curve was stable for at least 1 month. Hemolysis did not interfere, and turbidity from lipemia interfered only when absorbance exceeded 2.0 A. Results of this method (y) correlated well with those by the Turbitime method (y = 1.256x - 44.1 micrograms/L; n = 91; r = 0.991) and by a commercially available radioimmunoassay (Byk-Sangtec; y = 0.739x - 42.2 micrograms/L; n = 94; r = 0.991). The upper limit (95th percentile) of the reference interval for myoglobin was estimated at 57.9 micrograms/L. The positive predictive value for results of myoglobin at admission was 89% with this upper reference limit and 99% with 100 micrograms/L, whereas the negative predictive value was about 60% for both limits.

scholarly journals Hook Effect in Molar Pregnancy: A Report of Two Cases

2014 ◽  
Vol 6 (1) ◽  
pp. 49-50
Author(s):  
Hemprabha Gupta ◽  
Sipra Bagchi ◽  
Anushree Mittal
Keyword(s):  
South Asian ◽  
Molar Pregnancy ◽  
Hook Effect ◽  
Very High ◽  
Important Marker

ABSTRACT Molar pregnancy is associated with very high levels of hCG in serum as well as in urine and therefore is an important marker in its diagnosis and follow-up. However, at times very high levels of hCG may be associated with falsely low or negative hCG levels because of Hook effect. Here, we report two cases molar associated with Hook effect. How to cite this article Kunwar S, Gupta H, Bagchi S, Mittal A. Hook Effect in Molar Pregnancy: A Report of Two Cases. J South Asian Feder Obst Gynae 2014;6(1):49-50.

COMBINED MALIGNANT EXOPHTHALMOS OF GRAVES' DISEASE AND DIABETIC RETINOPATHY, TREATED BY HYPOPHYSEAL STALK SECTION

1964 ◽  
Vol 47 (4) ◽  
pp. 542-548 ◽  
Author(s):  
F. G. Schlesinger ◽  
F. Schwarz ◽  
P. J. der Kinderen ◽  
H. G. Parren ◽  
H. Verbiest
Keyword(s):  
Diabetes Mellitus ◽  
Diabetic Retinopathy ◽  
Psychological Stress ◽  
Corticosteroid Therapy ◽  
Male Patient ◽  
Clinical Picture ◽  
Pituitary Stalk ◽  
Antithyroid Drugs ◽  
Graves Disease

ABSTRACT Graves' disease developed in a 45 years old male patient suffering from long standing diabetes mellitus with mild retinopathy. During a period of overtreatment with antithyroid drugs and following psychological stress, progressive oedematous exophthalmos developed which caused an unusual and very alarming ophthalmological picture. Initially there was a good response to 131I and corticosteroid therapy, but later on pituitary stalk section had to be done, after which the condition of the eyes improved. The clinical picture was interpreted as the result of Graves' disease in a patient whose vessels were already damaged by diabetic retinopathy. Serum EPS activity was elevated before the operation and could not be demonstrated postoperatively.

Increased Estradiol Concentration of Unknown Origin

1991 ◽  
Vol 37 (12) ◽  
pp. 2152-2153
Author(s):  
John Vasiliades ◽  
T Hilgers ◽  
B Gentrup ◽  
J Remsburg
Keyword(s):  
White Woman ◽  
Unknown Origin ◽  
Interesting Case ◽  
Normal Serum ◽  
Serum Estradiol ◽  
Hormone Concentration ◽  
Normal Range ◽  
Hormonal Evaluation ◽  
Estradiol Concentration

Abstract We report an interesting case of above-normal serum estradiol concentration of unknown origin. A 30-year-old white woman was seen for infertility problems. Hormonal evaluation revealed the following results. Postovulatory progesterone concentrations and profile (a plot of hormone concentration vs time of cycle) were within the normal range for our laboratory (Table 1). However, the post-ovulatory estradiol concentrations were extremely high, although the curve appeared normal in profile (Table 1).

scholarly journals Development of a PTHrP Chemiluminescent Immunoassay to Assess Humoral Hypercalcemia of Malignancy

2021 ◽  
Vol 5 (Supplement_1) ◽  
pp. A1015-A1015
Author(s):  
Susan Louise Ashrafzadeh-Kian ◽  
Joshua Bornhorst ◽  
Alicia Algeciras-Schimnich
Keyword(s):  
Limit Of Detection ◽  
Reference Interval ◽  
Cross Reactivity ◽  
Humoral Hypercalcemia Of Malignancy ◽  
Clinical Sensitivity ◽  
Hypercalcemia Of Malignancy ◽  
Humoral Hypercalcemia ◽  
Hook Effect ◽  
Limit Of Quantitation ◽  
Acridinium Ester

Abstract Background: Measurement of parathyroid hormone related peptide (PTHrP) is helpful in the diagnosis and clinical management of patients suspected of humoral hypercalcemia of malignancy (HHM). In these patients uncontrolled release of PTHrP by tumor cells is responsible for the hypercalcemia and PTH concentrations are typically suppressed. Objective: Develop a sensitive and specific assay for quantitation of PTHrP in plasma. Method: Calibrators (PTHrP 1-86) and samples (50uL) were incubated with an anti-PTHrP goat polyclonal acridinium ester labeled antibody. Complexes were transferred and incubated in a microplate coated with an anti-PTHrP polyclonal rabbit antibody. After washing, the acridinium ester generated signal, which is directly proportional to the amount of PTHrP in sample, was quantified. Results: In this assay PTHrp was stable for 24 hours ambient, 3 days refrigerated, 34 days frozen and through 3 freeze/thaws. Intra and inter-assay imprecision in EDTA plasma (~0.16-35.0 pmol/L) ranged from 2.2-8.6% and 5-15%, respectively. The limit of detection was 0.04 pmol/L and the limit of quantitation was 0.16 pmol/L (15% CV). The analytical measuring range was 0.39-50.5 pmol/L (slope of 1.07 and r2 of 0.99). Average spike recovery was 98% (range 85-108%). The assay was not affected by hemoglobin of ≤500 mg/dL, triglycerides of ≤2000 mg/dL, or bilirubin of ≤50mg/dL. No hook effect was noted up to 500 pmol/L. PTH (1-84) did not cross-react in the assay. C-terminal PTHrP(107-139), and N-terminal PTHrP(1-36) had no significant cross-reactivity (≤1.1%). Mid-PTHrP(38-94) had 8.3% cross-reactivity. Comparison with an in-house PTHrP assay (n=267) showed an r2 of 0.96, and slope of 2.25 by Passing-Bablok regression fit. The 97.5% reference interval for PTHrP (n=114) was ≤0.7 pmol/L, however a higher concentration (≤4.2 pmol/L) was identified as a more specific clinical cut-off. A retrospective clinical validation study showed that using ≤4.2 pmol/L resulted in a 91% clinical sensitivity and a 98% clinical specificity. Conclusion: We have developed an analytically and clinically sensitive and specific PTHrP immunoassay. A cutoff of ≤4.2 pmol/L is clinically useful in the evaluation of patients suspected of hypercalcemia of malignancy.

scholarly journals Clinically relevant discrepancies between different rheumatoid factor assays

2018 ◽  
Vol 56 (10) ◽  
pp. 1749-1758 ◽  
Author(s):  
Willem J.J. Falkenburg ◽  
Helen J. von Richthofen ◽  
Jana Koers ◽  
Cas Weykamp ◽  
Marco W.J. Schreurs ◽  
...  
Keyword(s):  
Target Antigen ◽  
Disease Course ◽  
Rheumatoid Factors ◽  
Test Results ◽  
Rf Test ◽  
Rabbit Igg ◽  
Single Positive ◽  
Direct Elisa ◽  
Very High ◽  
Rf Measurements

Abstract Background: Accurate measurements of rheumatoid factors (RFs), autoantibodies binding IgG, are important for diagnosing rheumatoid arthritis (RA) and for predicting disease course. Worldwide, various RF assays are being used that differ in technique and target antigens. We studied whether assay choice leads to clinically important discrepancies in RF status and level. Methods: RF measurements using four commercial RF assays were compared in 32 RF+ samples. Using enzyme-linked immunosorbent assays (ELISAs), the influence of the target antigen source – human IgG (hIgG) versus rabbit IgG (rIgG) – on measured RF levels was investigated in arthralgia patients and RA patients. Results: Substantial discrepancies were found between RF levels measured in the four commercial assays. Six samples (19%) with RF levels below or slightly above the cutoff in the rIgG-based Phadia assay were RF+ in three assays using hIgG as the target antigen, some with very high levels. Direct ELISA comparisons of RF reactivity against hIgG and rIgG estimated that among 173 ACPA+ arthralgia patients, originally RF negative in rIgG-based assays, up to 10% were single positive against hIgG. Monoclonal RFs binding to hIgG and rIgG or hIgG only supported these findings. In a cohort of 69 early RA patients, virtually all RF responses reacted with both targets, although levels were still variable. Conclusions: The use of RF assays that differ in technique and target antigen, together with the different specificities of RF responses, leads to discrepancies in RF status and levels. This has important consequences for patient care if RA diagnosis and disease progression assessments are based on RF test results.

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