{"title":"Falsely elevated urinary C-peptide during angiotensin receptor-neprilysin inhibitor therapy: A case report.","authors":"Akihiro Morishige, Mitsuaki Nishioka, Yoko Nakabayashi, Akiyo Ishiguro, Kanae Shinkawa, Aki Fujinaga, Toshihiko Kobayashi, Masakazu Fukuda, Yutaka Suehiro, Yasuhiko Ohta, Takahiro Yamasaki","doi":"10.1177/00045632261435413","DOIUrl":"https://doi.org/10.1177/00045632261435413","url":null,"abstract":"<p><p>Background Urinary C-peptide testing is widely used to evaluate insulin secretion capacity from pancreatic β-cells. We report a case in which urinary C-peptide showed abnormally high levels during treatment with an angiotensin receptor-neprilysin inhibitor (ARNI). Case presentation The patient was a 54-year-old man undergoing treatment for type 2 diabetes mellitus and hypertension. Following an abnormal electrocardiogram during a health check-up, he was diagnosed with aortic valve insufficiency. During admission to the diabetes and endocrinology department for preoperative glycemic control, a clinical laboratory technologist first recognized a marked discrepancy between urinary and serum C-peptide results and reported this to the attending physician, prompting further investigation. A literature review revealed reports suggesting that ARNI administration may suppress C-peptide metabolism, potentially leading to elevation of measured values. Results The patient's excreted urinary C-peptide level decreased markedly after ARNI therapy was discontinued, suggesting that ARNI influences an increase in urinary C-peptide. Conclusions When excreted urinary C-peptide is abnormally elevated and discrepant from the serum C-peptide level, it is important to confirm ARNI use and follow laboratory-driven recommendations for retesting after discontinuation if needed. Prompt reporting of this finding by the clinical laboratory is essential for the accurate assessment of insulin secretion capacity.</p>","PeriodicalId":8005,"journal":{"name":"Annals of Clinical Biochemistry","volume":" ","pages":"45632261435413"},"PeriodicalIF":1.0,"publicationDate":"2026-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147466832","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Aditya Narayanan S, Ramya Devi D A, Renuka Pangaluri, Vinodhini V M, Arul Senghor K A
{"title":"Paraprotein interference in bilirubin assays: A case of multiple myeloma highlighting the reliability of dry chemistry.","authors":"Aditya Narayanan S, Ramya Devi D A, Renuka Pangaluri, Vinodhini V M, Arul Senghor K A","doi":"10.1177/00045632261435377","DOIUrl":"https://doi.org/10.1177/00045632261435377","url":null,"abstract":"<p><p>The presence of paraproteins in multiple myeloma can cause analytical interference, resulting in unusual and misleading biochemical outcomes. An uncommon but clinically relevant finding is the reporting of a negative direct bilirubin result on wet chemistry analyzers-an impossible outcome that strongly suggests analytical interference. A 60-year-old male presented with nonspecific symptoms. Liver function tests carried out on a wet chemistry analyzer indicated a total bilirubin of 0.39 mg/dL and a direct bilirubin of -7.67 mg/dL, which was not physiologically possible. There was no evidence of jaundice, and imaging appeared normal. Repeat testing with a dry chemistry analyzer indicated a total bilirubin of 1.0 mg/dL and a direct bilirubin of 0.1 mg/dL, aligning with the clinical picture. Further investigations confirmed the diagnosis of multiple myeloma with IgG-kappa monoclonal gammopathy. The discrepancy was attributed to paraprotein interference in the wet chemistry method. This case highlights a rare but important laboratory artifact-negative direct bilirubin due to paraprotein interference-and emphasizes the reliability of dry chemistry in such scenarios. Awareness of this interference is important for accurate diagnosis and avoiding unnecessary workup.</p>","PeriodicalId":8005,"journal":{"name":"Annals of Clinical Biochemistry","volume":" ","pages":"45632261435377"},"PeriodicalIF":1.0,"publicationDate":"2026-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147466848","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Response from the authors.","authors":"Emma Stevenson, Chelsey Walsh, Luke Hibberd","doi":"10.1177/00045632261435397","DOIUrl":"https://doi.org/10.1177/00045632261435397","url":null,"abstract":"","PeriodicalId":8005,"journal":{"name":"Annals of Clinical Biochemistry","volume":" ","pages":"45632261435397"},"PeriodicalIF":1.0,"publicationDate":"2026-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147455175","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Colleen Flannery, Alison Griffin, John Quinn, Clodagh Loughrey, Shari Srinivasan
{"title":"Establishment of a reference interval for calculated globulin on the Roche platform.","authors":"Colleen Flannery, Alison Griffin, John Quinn, Clodagh Loughrey, Shari Srinivasan","doi":"10.1177/00045632251367264","DOIUrl":"10.1177/00045632251367264","url":null,"abstract":"<p><p>BackgroundCalculated globulin, based on direct measurement of total protein and albumin, can be a useful addition to the routinely requested liver profile. However, a reference interval, established using CLSI EP28-A3c recommended direct methods, is lacking for the commonly used Roche method [albumin bromocresol green (BCG), total protein (biuret)].MethodsThis direct reference interval study was carried out between January and March 2024, based on Roche methods for total protein (biuret) and albumin (BCG). Reference individuals comprised 310 highly selected adults from primary care, ages ranging from 16 to 89 years. The CLSI guideline, EP28-A3c, was strictly followed. We also established a reference interval using an indirect approach for comparative purposes, using results from 8466 unselected primary care patients.ResultsThe reference interval for calculated globulin established using direct sampling techniques was 23 g/L (90% CI 22-24 g/L) - 35 g/L (90% CI 34-36 g/L). The reference interval established using indirect sampling techniques in a much larger unselected reference group was 22 g/L (90% CI 22-22 g/L) - 37 g/L (90% CI 37-37 g/L).ConclusionsWe have established a reference interval for calculated globulin, specific to the Roche total protein and BCG albumin methods. This will be a useful tool for other laboratories which use the Roche BCG albumin method, allowing adoption of this reference interval with a simple transference study. The range was a little broader but not materially altered (medians exactly the same) when strict exclusion criteria were removed and also when using a data mining approach, which resulted in a 27-fold larger reference group.</p>","PeriodicalId":8005,"journal":{"name":"Annals of Clinical Biochemistry","volume":" ","pages":"105-113"},"PeriodicalIF":1.0,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144726925","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ibrahim Hersi, Rachel L Griffiths, Rousseau Gama, Tejas Kalaria
{"title":"Efficacy and implications of minimum retesting intervals for HbA1c.","authors":"Ibrahim Hersi, Rachel L Griffiths, Rousseau Gama, Tejas Kalaria","doi":"10.1177/00045632251367278","DOIUrl":"10.1177/00045632251367278","url":null,"abstract":"","PeriodicalId":8005,"journal":{"name":"Annals of Clinical Biochemistry","volume":" ","pages":"182-184"},"PeriodicalIF":1.0,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144820421","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Byrne E, Twomey Pj, Crowley Rk, McKenna Mj, Kilbane M
{"title":"A method comparison of the Roche intact PTH method versus the Roche whole PTH (1-84) method: Examining the differences based on eGFR.","authors":"Byrne E, Twomey Pj, Crowley Rk, McKenna Mj, Kilbane M","doi":"10.1177/00045632251356826","DOIUrl":"10.1177/00045632251356826","url":null,"abstract":"<p><p>AimThird-generation whole PTH (1-84) parathyroid hormone (PTH) assays do not recognize the PTH 7-84 fragment whereas second-generation (intact) assays detect both 1-84 and 7-84 PTH fragments. This study aimed to compare the second-generation Roche intact PTH method with the third-generation Roche whole PTH (1-84) method, examining differences based on estimated glomerular filtration rate (eGFR).MethodsThe intact PTH method and whole PTH (1-84) method were compared using 100 serum samples selected across eGFR quintiles for chronic kidney disease (CKD) stages 1-5 in accordance with Kidney Disease: Improving Global Outcomes (KDIGO).ResultsMethod comparison based on eGFR showed that differences between both PTH methods were not significant at eGFR >60 mL/min/1.73 m<sup>2</sup>. There was a statistically significant difference at eGFR <60 mL/min/1.73 m<sup>2</sup>. The whole PTH (1-84) method produced lower results as eGFR decreased: CKD Stage 3 (mean difference: -21%; 95% confidence interval: -16 to -26%) to CKD Stage 5 (mean difference: -46%; 95% confidence interval: -40 to -52%).ConclusionsDifferences observed between the two assays may be due to second-generation PTH assays overestimating PTH concentration by measuring both 1-84 PTH and C-terminal fragments, notably PTH (7-84) in patients with significant renal impairment. The whole PTH (1-84) assay may be used to monitor metabolic bone disease risk. Initial dual reporting of PTH by both methods is recommended for eGFR <60 mL/min to educate users due to the difference in results.</p>","PeriodicalId":8005,"journal":{"name":"Annals of Clinical Biochemistry","volume":" ","pages":"98-104"},"PeriodicalIF":1.0,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144473796","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Roger Bramley, Daniel Herrera, Robert Barski, Michael Henderson
{"title":"Kidney stone analysis may miss diagnoses as demonstrated by a case of adenine phosphoribosyl transferase deficiency.","authors":"Roger Bramley, Daniel Herrera, Robert Barski, Michael Henderson","doi":"10.1177/00045632251367232","DOIUrl":"10.1177/00045632251367232","url":null,"abstract":"<p><p>Fourier-transformed infrared (FTIR) spectroscopy is a frequently requested test in patients with kidney stones. It is considered particularly useful when routine stone urine screens do not identify any significant abnormalities. This case report describes a patient with undiagnosed adenine phosphoribosyltransferase (APRT) deficiency, a disorder presenting with kidney stones, who had initial symptoms at 16 months of age but no diagnosis until they were 6 years old. Initial investigations including a urine stone screen did not show significant abnormalities; however, FTIR analysis suggested the stones had a significant component identified as lansoprazole, a drug the patient was not taking. After repeated stone formation, urinary tract infections and inpatient stays, the disorder was identified incidentally during validation of a method for purine and pyrimidines in urine. This case highlights that FTIR analysis, although useful, has pitfalls and that other investigations are of equal value in reaching a diagnosis.</p>","PeriodicalId":8005,"journal":{"name":"Annals of Clinical Biochemistry","volume":" ","pages":"177-180"},"PeriodicalIF":1.0,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144854277","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Shu Meguro, Yusuke Iwasaki, Junpei Ueda, Mikiko Okahashi, Yukio Kume, Takuji Kohzuma, Eri Shimizu, Hiroko Takeda, Satoshi Hirayama, Emiko Hosoba, Terumichi Nakagawa, Asako Sato
{"title":"Validation of the Japan Society of Clinical Chemistry (JSCC) recommended reference measurement procedure for glycated albumin determination.","authors":"Shu Meguro, Yusuke Iwasaki, Junpei Ueda, Mikiko Okahashi, Yukio Kume, Takuji Kohzuma, Eri Shimizu, Hiroko Takeda, Satoshi Hirayama, Emiko Hosoba, Terumichi Nakagawa, Asako Sato","doi":"10.1177/00045632251367235","DOIUrl":"10.1177/00045632251367235","url":null,"abstract":"<p><p>BackgroundTo clarify the fundamental characteristics of the Japan Society of Clinical Chemistry reference measurement procedure (JSCC RMP) for glycated albumin (GA), an additional performance study was performed and the correlation between the HPLC method and JSCC RMP was re-evaluated.MethodsRepeatability, detection limit, addition recovery, uncertainty of measurement, inter-laboratory comparison, correlation between JSCC RMP and HPLC method were evaluated.ResultsThe coefficient of variation (CV) of the total repeatability for the nine pretreated samples including isotope dilution and hydrolysis, defining that the averages of each of nine MS measurement samples are independent measurement vials, was 1.0%(<i>n</i> = 9). The limit of detection and Quantification of the GA values were 7.4 and 29.5 mmol/mol, respectively. Addition recovery rates were 99.6%-100.4%. The strong correlation (r = 0.999) of measured six serum samples between two laboratories was observed. Certified values and expanded uncertainties for JCCRM 611-2 (M, H, HH) using the JSCC RMP were as follows: JCCRM 611-2M: 232 and 9 mmol/mol, JCCRM611-2H: 359 and 14 mmol/mol, JCCRM611-2HH: 556 and 22 mmol/mol, respectively. The regression equation obtained using the Passing-Bablok method was GA (%)<sub>HPLC</sub> = 0.0523 × GA (mmol/mol) <sub>JSCC RMP</sub> + 1.315.ConclusionThe basic performance of the JSCC reference procedure for GA measurement was good, and similar results were obtained at other facilities, so it was considered to be robust and suitable as a reference method for GA measurement. Additionally, an equation was established to convert JSCC RMP (mmol/mol) values to the HPLC% values used in clinical practice.</p>","PeriodicalId":8005,"journal":{"name":"Annals of Clinical Biochemistry","volume":" ","pages":"123-131"},"PeriodicalIF":1.0,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144726928","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Blood hydrogen ion concentration: What purpose is served by expressing it as the inverse logarithm (pH)?","authors":"Michael J Murphy","doi":"10.1177/00045632251388544","DOIUrl":"10.1177/00045632251388544","url":null,"abstract":"","PeriodicalId":8005,"journal":{"name":"Annals of Clinical Biochemistry","volume":" ","pages":"95-97"},"PeriodicalIF":1.0,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145306686","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}