Olav Inge Klingenberg

• Fjeld, Bente; Sudmann-Day, Åshild Amelie; Grimholt, Runa Marie; Larstorp, Anne Cecilie Kjeldsen; Urdal, Petter & Klingenberg, Olav Inge (2022). Additional value of red blood cell parameters in predicting uncommon α-thalassemia; experience from 10 years of α-globin gene sequencing and copy number variation analysis. International Journal of Laboratory Hematology (IJLH). ISSN 1751-5521. 45(2), s. 250–259. doi: 10.1111/ijlh.14010. Fulltekst i vitenarkiv Vis sammendrag

  Introduction The diagnosis of rare forms of α-thalassemia requires laborious genetic analyses. Accurate sample selection for such evaluation is therefore essential. The main objectives of this study were to investigate the predictive power of red blood cell parameters to detect rare forms of α-thalassemia (substudy 1), and to explore the frequency of rare versus common forms of α-thalassemia in our sample population (substudy 2). Methods In substudy 1, we reviewed all blood samples selected for extended α-hemoglobinopathy evaluation at our laboratory during 2011–2020 (n = 1217), which included DNA sequencing and/or copy number variation analysis. We assessed α-thalassemia positive samples at different levels of mean corpuscular hemoglobin (MCH) alone and in combination with results for red blood cell count (RBC) or red cell distribution width (RDW). In substudy 2, we examined the distribution of α-thalassemia genotypes for all samples submitted to a first-tier hemoglobinopathy evaluation at our laboratory during 2014–2020 (n = 6495). Results In substudy 1, both RBC and RDW added predictive value in detecting rare forms of α-thalassemia in samples from adults and children. In adult samples with MCH ≤ 23 pg, the presence of erythrocytosis increased the detection rate from 27% to 74% as compared to non-erythrocytosis, while normal RDW increased the detection rate from 36% to 86% as compared to elevated RDW. In substudy 2, rare forms of α-thalassemia were detected in 12% of α-thalassemia positive samples. Conclusion Initial assessment of MCH, RBC, and RDW provided valuable predictive information about the presence of rare forms of α-thalassemia during hemoglobinopathy evaluation.

• Bekkenes, Maria Egeland; Fagerland, Morten; Solberg, Ole Geir; Aaberge, Lars; Klingenberg, Olav Inge & Norseth, Jon [Vis alle 7 forfattere av denne artikkelen] (2022). Exploring cardiac effects after oxytocin 2.5 IU or carbetocin 100 μg: A randomised controlled trial in women undergoing planned caesarean delivery. European Journal of Anaesthesiology. ISSN 0265-0215. 39(12), s. 928–938. doi: 10.1097/EJA.0000000000001763. Fulltekst i vitenarkiv Vis sammendrag

  BACKGROUND Oxytocin can stimulate release of myocardial biomarkers troponin I and T, prolong QTc and induce ST-depression. OBJECTIVE To explore cardiac changes after either intravenous carbetocin or oxytocin. STUDY DESIGN Exploratory phase 4 randomised controlled trial. SETTING Obstetrics units of Oslo University Hospital, Norway between September 2015 and May 2018. PARTICIPANTS Forty healthy, singleton pregnant women aged 18 to 50 years at gestational age at least 36 weeks with a planned caesarean delivery. INTERVENTIONS Participants were randomised to receive either oxytocin 2.5 IU or carbetocin 100 μg immediately after delivery. MAIN OUTCOME MEASURES The primary endpoint was the assessment of troponin I within 48 h of study drug administration. Troponin I and T, and creatine kinase myocardial band assessments were measured before spinal anaesthesia (baseline), and again at 4, 10 and 24 h after delivery. QTc, ST-depression and relative increase in heart rate were recorded from start of study drug administration to 10 min after delivery. All adverse events were monitored. RESULTS Compared with the carbetocin group, higher troponin I levels were observed in the oxytocin group at 4 h and 10 h after delivery. For both treatment groups, an increase from baseline in troponin I and T was most pronounced at 10 h after delivery, and it had begun to decline by 24 h. QTc increased with time after administration of both study drugs, with a mean maximum increase of 10.4 ms observed at 9 min (P< 0.001). No statistical differences were observed in QTc (P = 0.13) or ST-depression (P = 0.11) between the treatment groups. CONCLUSIONS Oxytocin 2.5 IU and carbetocin 100 μg caused a similar increase in QTc. The trial was underpowered with regards to ST-depression and the release of myocardial biomarkers and these warrant further investigation. Data from this trial will inform a larger phase 4 trial to determine potential drug differences in troponin release. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT02528136

• Larstorp, Anne Cecilie Kjeldsen; Salvador, Cathrin Lytomt; Svensvik, Bjørn Andreas; Klingenberg, Olav Inge & Distante, Sonia (2022). Neutrophil Gelatinase-Associated Lipocalin (NGAL) and cystatin C are early biomarkers of acute kidney injury associated with cardiac surgery. Scandinavian Journal of Clinical and Laboratory Investigation. ISSN 0036-5513. 82(5), s. 410–418. doi: 10.1080/00365513.2022.2114105. Fulltekst i vitenarkiv Vis sammendrag

  Acute kidney injury (AKI) is a serious complication in as much as half of the patients undergoing cardiac surgery, and early diagnosis and treatment are of the utmost importance. There is a need for robust biomarkers that can detect cardiac surgery-associated AKI (CSA-AKI) prior to rise in plasma creatinine, which typically occurs at least 48 h postoperatively. We compared pre- and 4, 12 and 48 h postoperative plasma (P) neutrophil gelatinase-associated lipocalin (NGAL), cystatin C, urea and creatinine, and urine (U) NGAL, as markers of AKI, in 49 patients (67% men, median age 65 years) scheduled for elective cardiac surgery (e.g. coronary artery bypass graft and/or valve replacement surgery) with the use of extracorporeal circulation. Patients with preoperative sepsis, renal replacement therapy, or estimated glomerular filtration rate <30 mL/min/1.73m2 were excluded. P- and U-NGAL were measured using the Roche Modular P (Roche Diagnostics®) NGAL immunoassay. According to AKIN/KDIGO criteria, nine patients (18%) were diagnosed with CSA-AKI. Compared to patients without CSA-AKI, these patients had significantly higher P-NGAL and P-cystatin C values 4 h (p-values .002 and <.001) and 12 h (p-values <.001 and <.001) postoperatively. The same differences were not observed for U-NGAL. Patients with AKI also had significantly higher P-creatinine 4 and 12 h postoperatively (p-values .001 and <.001), however the rise in P-creatinine was just above the upper reference limit. In conclusion, plasma NGAL and cystatin C seem to detect CSA-AKI earlier than the more commonly used biomarkers creatinine and urea.

• Georgina, Martin; Grimholt, Runa Marie; Le, Doan; Bechensteen, Anne Grete; Klingenberg, Olav Inge & Fjeld, Bente [Vis alle 11 forfattere av denne artikkelen] (2021). Hb Calgary (HBB: c.194G>T): A Highly Unstable Hemoglobin Variant with a β-Thalassemia Major Phenotype. Hemoglobin. ISSN 0363-0269. 45(4), s. 215–219. doi: 10.1080/03630269.2021.1956947. Fulltekst i vitenarkiv
• Grimholt, Runa Marie; Fjeld, Bente & Klingenberg, Olav (2021). Hemoglobinopathy gone astray—three novel forms of α-thalassemia in Norwegian patients characterized by quantitative real-time PCR and DNA sequencing. Scandinavian Journal of Clinical and Laboratory Investigation. ISSN 0036-5513. 81(8), s. 670–678. doi: 10.1080/00365513.2021.2004218. Fulltekst i vitenarkiv Vis sammendrag

  α-thalassemia is one of the most common monogenic diseases worldwide and is caused by reduced or absent synthesis of α-globin chains, most commonly due to deletions of one or more of the α-globin genes. α-thalassemia occurs with high frequency in tropical and subtropical regions of the world and are very rarely found in the indigenous Scandinavian population. Here, we describe four rare forms of α-thalassemia out of which three are novel, found in together 20 patients of Norwegian origin. The study patients were diagnosed during routine hemoglobinopathy evaluation carried out at the Department of Medical Biochemistry, Oslo University Hospital, Norway. The patients were selected for their thalassemic phenotype, despite Norway as country of origin. All samples went through standard hemoglobinopathy evaluation. DNA sequencing and copy number variation (CNV) analysis using quantitative real-time polymerase chain reaction (qPCR) was applied to detect sequence variants and uncommon deletions in the α-globin gene cluster, respectively. Deletion breakpoints were characterized using gap-PCR and DNA sequencing. DNA sequencing revealed a single nucleotide deletion in exon 3 of the HBA2 gene (NM_000517.4(HBA2):c.345del) and a novel deletion of 20 nucleotides in exon 2 of the HBA2 gene (NM_000517.4(HBA2):c.142_161del). qPCR CNV analysis detected two novel large deletions in the α-globin gene cluster, –(NOR) deletion covering both α-globin genes and (αα)Aurora Borealis affecting the regulatory region, leaving the downstream α-globin genes intact. Even though inherited globin gene disorders are extremely rare in indigenous Scandinavians, the possibility of a carrier state should not be ignored.

• Amundsen, Erik Koldberg; Binde, Christina; Christensen, Erik Egeland; Klingenberg, Olav Inge; Kvale, Dag & Holten, Aleksander Rygh (2021). Prognostic Value of Nucleated RBCs for Patients With Suspected Sepsis in the Emergency Department: A Single-Center Prospective Cohort Study. Critical Care Explorations. ISSN 2639-8028. 3(7), s. 1–9. doi: 10.1097/CCE.0000000000000490. Fulltekst i vitenarkiv
• Holm, Are Martin; Andreassen, Siw Lillevik; Christensen, Vivi Lycke; Kongerud, Johny; Almås, Øystein & Auråen, Henrik [Vis alle 10 forfattere av denne artikkelen] (2020). Hypogammaglobulinemia and risk of exacerbation and mortality in patients with COPD. The International Journal of Chronic Obstructive Pulmonary Disease. ISSN 1176-9106. 15, s. 799–807. doi: 10.2147/COPD.S236656. Fulltekst i vitenarkiv
• Grimholt, Runa Marie; Fjeld, Bente; Selsås, Hilde; Schwettmann, Lutz & Klingenberg, Olav (2019). Hb Aalesund (HBA2: c.400_406delAGCACCG), an Unstable α-Globin Variant Found in a Norwegian Patient Causing Moderate Hemolytic Anemia and Falsely High Hb A1c Using Ion Exchange High Performance Liquid Chromatography. Hemoglobin. ISSN 0363-0269. 43(2), s. 122–125. doi: 10.1080/03630269.2019.1614048. Fulltekst i vitenarkiv
• Grimholt, Runa Marie; Vestli, Anne; Urdal, Petter; Bechensteen, Anne Grete; Fjeld, Bente & Dalhus, Bjørn [Vis alle 7 forfattere av denne artikkelen] (2018). Hb Oslo [β42(CD1)Phe→Ile; HBB: c.127T>A]: A novel unstable hemoglobin variant found in a Norwegian patient. Hemoglobin. ISSN 0363-0269. 42(2), s. 78–83. doi: 10.1080/03630269.2018.1468773. Fulltekst i vitenarkiv
• Grimholt, Runa Marie; Harteveld, Cornelis; Arkesteijn, Sandra G J; Fjeld, Bente & Klingenberg, Olav (2018). Characterization of Two Deep Intronic Variants on the β-Globin Gene with Inconsistent Interpretations of Clinical Significance. Hemoglobin. ISSN 0363-0269. 42(2), s. 126–128. doi: 10.1080/03630269.2018.1473255. Fulltekst i vitenarkiv
• Sagedal, Solbjørg; Sandvik, Leiv; Klingenberg, Olav & Sandset, Per Morten (2017). β-Thromboglobulin may not reflect platelet activation during haemodialysis with the HeprAN membrane. Scandinavian Journal of Clinical and Laboratory Investigation. ISSN 0036-5513. 77(8), s. 679–684. doi: 10.1080/00365513.2017.1397288.
• Klingenberg, Olav; Furuset, Torill; Hestbråten, Camilla Røising; Hallberg, Marit Hansen; Steiro, Astrid & Orset, Iren Røstbakken [Vis alle 7 forfattere av denne artikkelen] (2017). HbA1c analysis by capillary electrophoresis?comparison with chromatography and an immunological method. Scandinavian Journal of Clinical and Laboratory Investigation. ISSN 0036-5513. 77(6), s. 458–464. doi: 10.1080/00365513.2017.1338747. Fulltekst i vitenarkiv
• Sudmann, Åshild Amelie; Piehler, Armin; Klingenberg, Olav & Urdal, Petter (2015). Six-day stability of erythrocyte and reticulocyte parameters in-vitro: A comparison of blood samples from healthy, iron-deficient, and thalassemic individuals. Scandinavian Journal of Clinical and Laboratory Investigation. ISSN 0036-5513. 75(3), s. 247–253. doi: 10.3109/00365513.2014.1000370.
• Berntsen, Natalie Lie; Klingenberg, Olav; Juran, Brian D.; Benito De Valle, Maria; Lindkvist, Björn & Lazaridis, Konstantinos N. [Vis alle 9 forfattere av denne artikkelen] (2015). Association between HLA haplotypes and increased serum levels of IgG4 in patients with primary sclerosing cholangitis. Gastroenterology. ISSN 0016-5085. 148(5), s. 924–927.e2. doi: 10.1053/j.gastro.2015.01.041.
• Grimholt, Runa Marie; Urdal, Petter; Klingenberg, Olav & Piehler, Armin (2014). Rapid and reliable detection of alpha-globin copy number variations by quantitative real-time PCR. BMC Hematology. ISSN 2052-1839. doi: 10.1186/2052-1839-14-4.
• Urdal, Petter; Amundsen, Erik Koldberg; Toska, Karin & Klingenberg, Olav (2014). Automated alarm to detect antigen excess in serum free immunoglobulin light chain kappa and lambda assays. Scandinavian Journal of Clinical and Laboratory Investigation. ISSN 0036-5513. 74(7), s. 575–581. doi: 10.3109/00365513.2014.915426.
• Henriksson, Carola Elisabeth; Hellum, Marit Synnøve; Haug, Kari Bente Foss; Aass, Hans Christian; Joø, Gun Brit & Øvstebø, Reidun [Vis alle 9 forfattere av denne artikkelen] (2011). Anticoagulant effects of an antidiabetic drug on monocytes in vitro. Thrombosis Research. ISSN 0049-3848. 128(5), s. E100–E106. doi: 10.1016/j.thromres.2011.07.007.
• Sagedal, Solbjørg; Witczak, Bartlomiej J; Osnes, Kåre; Hartmann, Anders; Os, Ingrid & Eikvar, Lars Kristian [Vis alle 8 forfattere av denne artikkelen] (2011). A Heparin-Coated Dialysis Filter (AN69 ST) Does Not Reduce Clotting during Hemodialysis when Compared to a Conventional Polysulfone Filter (F x 8). Blood Purification. ISSN 0253-5068. 32(3), s. 151–155. doi: 10.1159/000325227.
• Bachmann-Harildstad, Gregor; Stenklev, Niels Chr.; Myrvoll, Elin Alise; Jablonski, Greg & Klingenberg, Olav (2011). Beta-Trace Protein as a Diagnostic Marker for Perilymphatic Fluid Fistula: A Prospective Controlled Pilot Study to Test a Sample Collection Technique. Otology & Neurotology. ISSN 1531-7129. 32(1), s. 7–10. doi: 10.1097/MAO.0b013e3181fc74d0.
• Jensen, Torstein; Kierulf, Peter; Sandset, Per Morten; Klingenberg, Olav; Joø, Gun Brit & Godal, Hans Chr [Vis alle 7 forfattere av denne artikkelen] (2007). Fibrinogen and fibrin induce synthesis of proinflammatory cytokines from peripheral blood mononuclear cells. Thrombosis and Haemostasis. ISSN 0340-6245. 97(5), s. 822–829. doi: 10.1160/TH07-01-0039. Vis sammendrag

  Fibrinogen in plasma includes three main fractions; high-molecular-weight (HMW)-fibrinogen, low-molecular-weight (LMW)-fibrinogen, and very-low-molecular-weight (LMW')-fibrinogen. During acute-phase conditions, plasma fibrinogen levels and the HMW-/LMW-fibrinogen ratio increase rapidly due to increased synthesis of HMW-fibrinogen. The consequences of elevated plasma fibrinogen levels and local deposition of fibrin in inflammatory tissues observed during acute-phase conditions are not clear. We wanted to investigate proinflammatory effects of fibrinogen and fibrin on peripheral blood mononuclear cells (PBMC) as reflected by altered mRNA expression and synthesis of the proinflammatory cytokines IL-6, TNF-alpha and IL-1beta, and to explore the significance of altered HMW-/LMW-fibrinogen ratio. PBMC were isolated from whole blood using Lymphoprep((R)). HMW-fibrinogen was separated from unfractioned fibrinogen by ammonium sulphate precipitation. Cells were incubated with unfractioned fibrinogen, HMW-fibrinogen or fibrin. Cytokine levels in cell lysates were determined using ELISA assays. Real-time PCR was used for mRNA quantification. We found that fibrinogen significantly increased mRNA levels, and induced synthesis of the proinflammatory cytokines IL-6 and TNF-alpha in PBMC in a dose dependent manner. Median (25, 75 percentile) IL-6 and TNF-alpha concentrations were 12 (5, 40) pg/ml and 16 (0,61) pg/ml, respectively. Median mRNA quantity was increased 12.3- (6.6, 48.6) and 1.7- (1.5, 6.5) fold for IL-6 and TNF-alpha compared to controls. The stimulatory effect of unfractioned fibrinogen was not significantly different from HMW-fibrinogen. Fibrinogen and fibrin were equally effective in promoting cytokine synthesis from PBMC. The results support that fibrin and fibrinogen may actively modulate the inflammatory process by inducing synthesis of proinflammatory cytokines from PBMC.

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• Bekkenes, Maria Egeland; Fagerland, Morten; Solberg, Ole Geir; Aaberge, Lars; Klingenberg, Olav Inge & Norseth, Jon [Vis alle 7 forfattere av denne artikkelen] (2023). Reply to: Exploring cardiac effects after oxytocin 2.5 IU or carbetocin 100 μg - A randomised controlled trial in women undergoing planned caesarean delivery. European Journal of Anaesthesiology. ISSN 0265-0215. 40(6), s. 453–454. doi: 10.1097/EJA.0000000000001841.
• Vinnes, Erik Wilhelm; Lillemoen, Paul Kjetel Soldal; Klingenberg, Olav Inge; Fjeld, Bente; Iversen, Per Ole & Brodwall, Kristoffer [Vis alle 7 forfattere av denne artikkelen] (2023). Sigdcellesykdom – kliniske manifestasjoner og diagnostikk. Tidsskrift for Den norske legeforening. ISSN 0029-2001. 143(3). doi: 10.4045/tidsskr.22.0353. Fulltekst i vitenarkiv
• Hildrum, Jonas Meek; Fjeld, Bente; Risahagen, Siv Mørkestøl; Bernatek, Barbara Jean & Klingenberg, Olav Inge (2021). Assessment of Hemoglobin A2 stability at room temperature during 24 or 25 days as measured by high pressure liquid chromatography and capillary electrophoresis. International Journal of Laboratory Hematology (IJLH). ISSN 1751-5521. 43(5), s. e266–e270. doi: 10.1111/ijlh.13555.
• Bekkenes, Maria Egeland; Jørgensen, Marte Morin; Jacobsen, Anne Flem; Fagerland, Morten; Rakstad-Larsen, Helene & Solberg, Ole Geir [Vis alle 10 forfattere av denne artikkelen] (2021). A study protocol for the cardiac effects of a single dose of either oxytocin 2.5 IU or carbetocin 100 µg after caesarean delivery: A prospective randomized controlled multi-centre trial in Norway. F1000 Research. ISSN 2046-1402. 10:973, s. 1–17. doi: 10.12688/f1000research.73112.1. Fulltekst i vitenarkiv
• Grimholt, Runa Marie; Urdal, Petter; Klingenberg, Olav Inge & Piehler, Armin (2019). Correction to: Rapid and reliable detection of α-globin copy number variations by quantitative real-time PCR (BMC Hematology (2014) 14 (4) DOI: 10.1186/2052-1839-14-4). BMC Hematology. ISSN 2052-1839. 19(1). doi: 10.1186/s12878-019-0144-5.
• Fjeld, Bente; Sudmann-Day, Åshild Amelie; Grimholt, Runa Marie & Klingenberg, Olav (2019). Kan pasienten ha talassemi eller en hemoglobinvariant? Tidsskrift for Den norske legeforening. ISSN 0029-2001. 139(17). doi: 10.4045/tidsskr.19.0121.
• Grimholt, Runa Marie; Fjeld, Bente; Piehler, Armin & Klingenberg, Olav (2017). Chasing the Northern Light - (--)NOR and (αα) Aurora Borealis; two novel deletions causing alpha-thalassemia found in Norwegian patients. Vis sammendrag

  Introduction: Alpha-thalassemia is one of the most common monogenic diseases worldwide and is caused by reduced or absent synthesis of alpha-globin chains, most commonly due to deletions of one or more of the alpha-globin genes. Sequence variants that alter gene expression or deletions involving upstream regulatory elements are less frequent. Alpha-thalassemia occurs with high frequency in tropical and subtropical regions of the world. For people of Northern European origin, inherited hemoglobin disorders, such as alpha-thalassemia, are extremely rare. Here, we describe two novel deletions causing alpha-thalassemia found in patients of Norwegian origin. Materials and Methods: The study patients were diagnosed during routine hemoglobinopathy evaluation carried out at the Department of Medical Biochemistry, Oslo University Hospital, Norway. The patients were selected for their thalassemic phenotype, despite Norway as country of origin. All samples went through standard hemoglobinopathy evaluation. Quantitative real-time PCR copy number variation (CNV) analysis was applied to detect uncommon deletions in the alpha-globin gene cluster. Deletion breakpoints were characterized using gap-PCR and DNA sequencing. Results: Two novel deletions, (--)NOR and (αα)Aurora Borealis, were identified in altogether nine patients from two and one families, respectively, all of Norwegian origin presenting with microcytosis. The (--)NOR deletion was a result of homologous recombination deleting both alpha-globin genes. The (αα)Aurora Borealis deletion caused alpha-thalassemia by affecting the upstream regulatory element, HS-40, leaving the alpha-globin genes intact. Conclusions: Even though inherited hemoglobin disorders are extremely rare in indigenous Northern Europeans, the possibility of a carrier state should not be ignored.

• Grimholt, Runa Marie; Fjeld, Bente; Klingenberg, Olav & Piehler, Armin P (2017). Alfa-thalassemi på avveie – sjeldne former for alfa-thalassemi funnet hos norske pasienter. Vis sammendrag

  Bakgrunn: Alfa-thalassemi er en av de vanligste monogene sykdommene i verden og skyldes i hovedsak delesjoner av alfa-globingenene, som gir nedsatt eller ingen produksjon av alfa-globinkjeder. Sekvensvarianter og delesjoner av det regulerende området oppstrøms for alfa-globingenene, HS-40, forekommer langt sjeldnere. Alfa-thalassemi er hyppig forkommende i områder der malaria er eller har vært vanlig. Med dagens globale migrasjonsmønster er hemoglobinopatier blitt stadig vanligere forekommende også i det norske helsevesen, men hos individer av norsk opprinnelse er det svært sjelden. Her beskriver vi tre former for alfa-thalassemi påvist hos etnisk norske pasienter. Material og metode: Pasientene ble diagnostisert gjennom rutinemessig hemoglobinopati-utredning ved Avdeling for medisinsk biokjemi, Oslo universitetssykehus, Ullevål. Standard hemoglobinopati-utredning, som innebærer analytisk hematologi, måling av ferritin og CRP, hemoglobintyping og gap-PCR som påviser de syv vanligste delesjonene som gir alfa-thalassemi, ble utført på alle pasientene. DNA sekvensering av alfa-globingenene ble brukt til å påvise sekvensvarianter og sanntids PCR ble brukt til å påvise sjeldne delesjoner i alfa-globin genclusteret. Resultater: To nye delesjoner, (αα)Aurora Borealis og (--)NOR ble påvist ved sanntids PCR hos til sammen ni pasienter fra henholdsvis en og to familier. (αα)Aurora Borealis fører til alfa-thalassemi ved at det regulatoriske området, HS-40, er deletert. (--)NOR er et resultat av homolog overkryssing og rammer begge alfa-globingenene. I tillegg ble det påvist en sjelden sekvensvariant i HBA2 genet som gir alfa-thalassemi hos åtte pasienter fra fem ulike familier. Alle pasientene var av norsk opprinnelse og hadde mikrocytose med eller uten anemi. Konklusjon: Selv om thalassemi er svært sjelden hos etnisk norske individer, skal muligheten for bærertilstand likevel ikke utelukkes.

• Klingenberg, Olav (2017). Hemoglobin amino acids by the numbers. Scandinavian Journal of Clinical and Laboratory Investigation. ISSN 0036-5513. 77(1), s. 1–1. doi: 10.1080/00365513.2017.1267428.
• Grimholt, Runa Marie; Sudmann, Åshild Amelie; Piehler, Armin; Urdal, Petter & Klingenberg, Olav (2014). Hb Ullevaal [β78(EF2)Leu→Val; HBB: c.235C>G], a New Hemoglobin Variant Interfering with Hb A1c Measurement Using a Cation Exchange High Performance Liquid Chromatography Method. Hemoglobin. ISSN 0363-0269. 38(2), s. 130–132. doi: 10.3109/03630269.2013.858640.
• Hausken, Jon; Klingenberg, Olav; Mørkrid, Lars; Rollag, Halvor; Foss, Aksel & Midtvedt, Karsten (2012). Elevated Troponin I and NT-proBNP at the Time of Transplantation May Predict a Major Adverse Cardiac Event in the Early Postoperative Period After Renal Transplantation. Transplantation. ISSN 0041-1337. 94(2), s. E15–E16. doi: 10.1097/TP.0b013e31825b7633.

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