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McCarroll K, Fitzpatrick D, McCormack M, Abdelfadil S, Crowley V, Lannon R, Healy M. Falsely elevated parathyroid hormone in a patient with osteoporosis: a case report and review. Osteoporos Int 2024; 35:737-740. [PMID: 38151628 DOI: 10.1007/s00198-023-07006-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Accepted: 12/18/2023] [Indexed: 12/29/2023]
Abstract
BACKGROUND Parathyroid hormone (PTH) measurements can be falsely elevated due to the hormone binding to other molecules (macro-PTH) or immunoassay interference with heterophile, human anti-animal or other antibodies. This is rare but could lead to incorrect diagnosis, unnecessary investigations or avoidance of teriparatide treatment. We report a case of falsely high PTH levels due to assay interference and review the literature on cases of spuriously elevated PTH. CASE REPORT An 87-year-old woman attending our bone health clinic with osteoporosis had persistently elevated PTH (383-784 pg/ml) using the Roche Cobas e801 immunoassay despite having normal serum calcium, phosphate, 25 hydroxyvitamin D (> 50 nmol/l) and eGFR (> 60 ml/min). To rule out falsely elevated PTH, a polyethylene glycol precipitation (PEG) test was performed which recovered less than 10% of the hormone resulting in a normal level. PTH was also tested on a different assay (Atellica Siemens) that identified a result of 27 pg/ml. The findings were consistent with immunoassay interference likely due to heterophile antibodies giving rise to a spuriously high PTH. DISCUSSION The presence of unexpectedly high PTH levels should alert physicians to the possibility of false results due to assay interference or macro-PTH. This highlights the importance of clinically correlating results and of good communication with the testing laboratory. Here, we present the case of an 87-year-old woman with spuriously elevated PTH levels due to immunoassay interference likely mediated by heterophile antibodies. The presence of unexpectedly high PTH levels should prompt consideration of the possibility of false results due to assay interference or macro-PTH.
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Affiliation(s)
- Kevin McCarroll
- Mercer's Institute for Successful Ageing, St James's Hospital, Dublin, Ireland
- School of Medicine, Trinity College Dublin, Dublin, Ireland
| | - Donal Fitzpatrick
- Mercer's Institute for Successful Ageing, St James's Hospital, Dublin, Ireland.
- School of Medicine, Trinity College Dublin, Dublin, Ireland.
| | | | | | - Vivion Crowley
- Biochemistry Department, St James's Hospital, Dublin, Ireland
| | - Rosaleen Lannon
- Mercer's Institute for Successful Ageing, St James's Hospital, Dublin, Ireland
- School of Medicine, Trinity College Dublin, Dublin, Ireland
| | - Martin Healy
- Mercer's Institute for Successful Ageing, St James's Hospital, Dublin, Ireland
- School of Medicine, Trinity College Dublin, Dublin, Ireland
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2
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Markov AM, Jasim S, Carson JP. A Puzzling Case of Elevated Parathyroid Hormone. J Appl Lab Med 2024; 9:399-403. [PMID: 38084943 DOI: 10.1093/jalm/jfad078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Accepted: 09/28/2023] [Indexed: 03/02/2024]
Affiliation(s)
- Alexander M Markov
- Division of Endocrinology, Metabolism & Lipid Research, Washington University in St.Louis School of Medicine, St. Louis, MO 63110, United States
| | - Sina Jasim
- Division of Endocrinology, Metabolism & Lipid Research, Washington University in St.Louis School of Medicine, St. Louis, MO 63110, United States
| | - Jennifer Powers Carson
- Division of Endocrinology, Metabolism & Lipid Research, Washington University in St.Louis School of Medicine, St. Louis, MO 63110, United States
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3
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D'Aurizio F, Kratzsch J, Gruson D, Petranović Ovčariček P, Giovanella L. Free thyroxine measurement in clinical practice: how to optimize indications, analytical procedures, and interpretation criteria while waiting for global standardization. Crit Rev Clin Lab Sci 2023; 60:101-140. [PMID: 36227760 DOI: 10.1080/10408363.2022.2121960] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Thyroid dysfunctions are among the most common endocrine disorders and accurate biochemical testing is needed to confirm or rule out a diagnosis. Notably, true hyperthyroidism and hypothyroidism in the setting of a normal thyroid-stimulating hormone level are highly unlikely, making the assessment of free thyroxine (FT4) inappropriate in most new cases. However, FT4 measurement is integral in both the diagnosis and management of relevant central dysfunctions (central hypothyroidism and central hyperthyroidism) as well as for monitoring therapy in hyperthyroid patients treated with anti-thyroid drugs or radioiodine. In such settings, accurate FT4 quantification is required. Global standardization will improve the comparability of the results across laboratories and allow the development of common clinical decision limits in evidence-based guidelines. The International Federation of Clinical Chemistry and Laboratory Medicine Committee for Standardization of Thyroid Function Tests has undertaken FT4 immunoassay method comparison and recalibration studies and developed a reference measurement procedure that is currently being validated. However, technical and implementation challenges, including the establishment of different clinical decision limits for distinct patient groups, still remain. Accordingly, different assays and reference values cannot be interchanged. Two-way communication between the laboratory and clinical specialists is pivotal to properly select a reliable FT4 assay, establish reference intervals, investigate discordant results, and monitor the analytical and clinical performance of the method over time.
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Affiliation(s)
- Federica D'Aurizio
- Department of Laboratory Medicine, University Hospital of Udine, Udine, Italy
| | - Jürgen Kratzsch
- Institute for Laboratory Medicine, Clinical Chemistry and Molecular Diagnostics, University Hospital, University of Leipzig, Leipzig, Germany
| | - Damien Gruson
- Department of Clinical Biochemistry, Cliniques Universitaires St-Luc and Université Catholique de Louvain, Brussels, Belgium
| | - Petra Petranović Ovčariček
- Department of Oncology and Nuclear Medicine, University Hospital Center Sestre milosrdnice, Zagreb, Croatia
| | - Luca Giovanella
- Clinic for Nuclear Medicine and Competence Center for Thyroid Diseases, Imaging Institute of Southern Switzerland, Ente Ospedaliero Cantonale, Bellinzona, Switzerland.,Clinic for Nuclear Medicine and Thyroid Center, University and University Hospital of Zurich, Zurich, Switzerland
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4
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Abstract
Primary hyperparathyroidism (PHPT) is classically characterized by hypercalcemia with elevated or inappropriately normal parathyroid hormone (PTH) levels. Elevated PTH levels in the presence of normal calcium levels are not infrequently found during the evaluation of metabolic bone disorders or kidney stone disease. This can be caused by secondary hyperparathyroidism (SHPT) or normocalcemic primary hyperparathyroidism (NPHPT). NPHPT is due to autonomous parathyroid function whereas SHPT is caused by a physiologic stimulation to PTH secretion. Many medical conditions and medications can contribute to SHPT, and differentiation between SHPT and NPHPT may be difficult. Cases are presented to illustrate examples. In this paper, we review the distinction between SHPT and NPHPT as well as end organ effects of NPHPT and outcomes of surgery in NPHPT. We suggest that the diagnosis of NPHPT be made only after careful exclusion of causes of SHPT and consideration of medications that can increase PTH secretion. Further, we advise a conservative approach to surgery in NPHPT.
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Affiliation(s)
- Joseph L Shaker
- Correspondence: Joseph L. Shaker, MD, W129N7155 Northfield Dr, Menomonee Falls, WI 53051, USA.
| | - Robert A Wermers
- Department of Medicine and Division of Endocrinology, Diabetes, Metabolism and Nutrition, Mayo Clinic, Rochester, MN, USA
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Cheng J, Mu D, Wang D, Qiu L, Cheng X. Preanalytical considerations in parathyroid hormone measurement. Clin Chim Acta 2023; 539:259-265. [PMID: 36566956 DOI: 10.1016/j.cca.2022.12.022] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Revised: 12/20/2022] [Accepted: 12/20/2022] [Indexed: 12/24/2022]
Abstract
Automated immunoassays used to evaluate parathyroid function are vulnerable to different types of interference, which can affect clinical practices. This review provides a detailed overview of the six main types of interference known to affect the measurement of parathyroid hormone (PTH): heterophilic antibodies, biotin, PTH fragments, oxidized PTH (oxPTH), phosphorylated PTH, and some preanalytical factors. Because the prevalence of some of these conditions has been reported to approach 11.7%, and the frequency of testing for parathyroid function is important, the scale of the problem might be tremendous. Potential interference in parathyroid function testing should always be suspected whenever clinical or biochemical discrepancies arise. Their identification typically relies on additional laboratory tests, including method comparison, serial dilution, blocking reagent studies, affinity adsorption, and polyethylene glycol precipitation. Moreover, some of these issues can be mitigated with the development of mass spectrometry. This review also evaluated the clinical impact of parathyroid interference on immunoassays, including misdiagnosis, inappropriate parathyroidectomy; and delay in receiving appropriate therapy. Hence, strong communication should be maintained between the clinician and laboratory to avoid such scenarios.
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Affiliation(s)
- Jin Cheng
- Department of Laboratory Medicine, Peking Union Medical College Hospital, Peking Union Medical College & Chinese Academy of Medical Science, Beijing 100730, China
| | - Danni Mu
- Department of Laboratory Medicine, Peking Union Medical College Hospital, Peking Union Medical College & Chinese Academy of Medical Science, Beijing 100730, China
| | - Danchen Wang
- Department of Laboratory Medicine, Peking Union Medical College Hospital, Peking Union Medical College & Chinese Academy of Medical Science, Beijing 100730, China
| | - Ling Qiu
- Department of Laboratory Medicine, Peking Union Medical College Hospital, Peking Union Medical College & Chinese Academy of Medical Science, Beijing 100730, China; State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Science and Peking Union Medical College, Beijing, China
| | - Xinqi Cheng
- Department of Laboratory Medicine, Peking Union Medical College Hospital, Peking Union Medical College & Chinese Academy of Medical Science, Beijing 100730, China.
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Calabrò V, Lovriha S, Zandonà L, Sirianni F, Fabris B, Bernardi S. A case report of PTH elevation due to immunoassay interference. J Endocrinol Invest 2022; 45:2201-2202. [PMID: 35849325 DOI: 10.1007/s40618-022-01871-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Accepted: 07/12/2022] [Indexed: 11/26/2022]
Affiliation(s)
- V Calabrò
- SS Endocrinologia, UCO Medicina Clinica, Ospedale di Cattinara, ASUGI, 34149, Trieste, Italy
| | - S Lovriha
- SS Endocrinologia, UCO Medicina Clinica, Ospedale di Cattinara, ASUGI, 34149, Trieste, Italy
- Dipartimento di Scienze Mediche Chirurgiche e della Salute, Università degli Studi di Trieste, 34149, Trieste, Italy
| | - L Zandonà
- SC Laboratorio Unico, Ospedale Maggiore, ASUGI, 34125, Trieste, Italy
| | - F Sirianni
- SC Laboratorio Unico, Ospedale Maggiore, ASUGI, 34125, Trieste, Italy
| | - B Fabris
- SS Endocrinologia, UCO Medicina Clinica, Ospedale di Cattinara, ASUGI, 34149, Trieste, Italy
- Dipartimento di Scienze Mediche Chirurgiche e della Salute, Università degli Studi di Trieste, 34149, Trieste, Italy
| | - S Bernardi
- SS Endocrinologia, UCO Medicina Clinica, Ospedale di Cattinara, ASUGI, 34149, Trieste, Italy.
- Dipartimento di Scienze Mediche Chirurgiche e della Salute, Università degli Studi di Trieste, 34149, Trieste, Italy.
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