ABSTRACT
Objectives
Thrombotic thrombocytopenic purpura (TTP) is a rare but life-threatening hematological disorder. Early differentiation between TTP and primary immune thrombocytopenia (ITP) accompanied by anemia is crucial to initiate an appropriate therapeutic strategy. The objective of this study was to evaluate the predictive value of red blood cell lifespan (RBCLS), determined using the carbon monoxide breath test, in the differential diagnosis of these two diseases.
Methods
We conducted a retrospective analysis of 23 patients with TTP and 32 patients with ITP accompanied by anemia. RBCLS measurements were compared and evaluated between these two patient groups.
Results
TTP patients had a significantly shorter mean RBCLS (20 ± 8 days) than patients with ITP accompanied by anemia (77 ± 22 days, P < 0.001) and healthy controls (114 ± 25 days, P < 0.001). In TTP patients, RBCLS showed a significant negative correlation with reticulocyte percentage and lactic dehydrogenase levels (P < 0.001). When using a standard baseline of 75 days, RBCLS demonstrated a sensitivity of 100% and specificity of 53.1% in identifying TTP. The diagnostic accuracy could reach 93% by excluding the impact of gastrointestinal bleeding. By employing the Receiver Operator Characteristics (ROC) curve, the area under the curve for RBCLS was 0.985 (95% CI: 0–1, P < 0.01) in predicting TTP, with an optimal cut-off value of 32 days, and sensitivity and specificity of 95.7% and 96.9%, respectively.
Conclusions
Our study proposes a simple and accessible method for evaluating RBCLS to differentiate between TTP and ITP accompanied by anemia.
Introduction
Thrombotic thrombocytopenic purpura (TTP) is a rare but potentially fatal hematologic disorder characterized by microangiopathic hemolytic anemia, severe thrombocytopenia (<30 x109/L), and variable degree of organ damage. Its incidence is 2–6 per million individuals [1–4]. The primary pathogenesis of TTP involves a deficiency in the activity of ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13), a protease responsible for cleaving von Willebrand factor. TTP is classified as congenital TTP (cTTP) or immune-mediated TTP (iTTP) based on the underlying mechanisms of ADAMTS13 deficiency. Over 95% of TTP cases are classified as iTTP, whereas cTTP accounts for less than 5% of cases [5–7]. If left untreated, TTP is almost universally fatal; however, the introduction of plasma exchange and immunosuppression has significantly reduced mortality rates in acute iTTP, from >90% to <5–20% [8–10]. As death often occurs within the initial days of management, early diagnosis and differentiation from other forms of thrombocytopenia and thrombotic microangiopathy are crucial. Primary immune thrombocytopenia (ITP) is the most common bleeding disorder observed in clinical practice [11]. There are significant distinctions in treatment and prognosis between TTP and ITP. When ITP presents with anemia or does not respond to conventional treatment, it is crucial to distinguish it from TTP during diagnosis due to similarities in symptoms, and measuring ADAMTS13 activity is necessary.
In clinical practice, rapid differential diagnosis of TTP and ITP with anemia remains challenging. ITP diagnosis primarily relies on excluding other disorders that can cause thrombocytopenia, as there are no specific diagnostic markers available [11]. ADAMTS13 activity is a unique and well-established biomarker to diagnose TTP [7]. However, ADAMTS13 testing is not widely accessible in many hospitals, and obtaining results can take several days, making prompt diagnosis impractical. Due to the high early mortality rate of TTP, guidelines suggest starting plasma exchange based on risk assessment models like PLASMIC or French score, without waiting for ADAMTS13 results. These scores aim to differentiate TTP from other thrombotic microangiopathy conditions [12–14] but may be misleading if used incorrectly and are not suitable for distinguishing between TTP and ITP with anemia. Hemolytic markers such as haptoglobin, lactate dehydrogenase, reticulocyte count, and presence of schistocytes in a blood smear can aid in distinguishing between TTP and ITP with anemia. Nevertheless, haptoglobin testing is not widely conducted in some hospitals. Lactate dehydrogenase and reticulocyte count are not exclusive to hemolysis, and the absence of schistocytes does not rule out TTP definitively [15]. Therefore, early differential diagnosis cannot rely solely on the presence or absence of schistocytes. Consequently, there is a need for a simple and rapid screening test to enable timely initial assessment in busy clinical practice.
The red blood cell lifespan (RBCLS) refers to the average period of time that red blood cells (RBCs) survive in circulation after being released from the bone marrow. The measurement of RBCLS is crucial in diagnosing anemic diseases and serves as the gold standard diagnostic criterion for hemolytic anemia [16]. In recent years, Levitt's carbon monoxide (CO) breath test, a novel method for measuring RBCLS, has become widely used in clinical practice. The principle behind this test is that endogenous CO primarily originates from degraded RBCs. In comparison to traditional labeling methods, Levitt's CO breath test provides equally stable RBCLS results while offering the advantages of non-invasive, speed, accuracy, cost-effectiveness, and easy promotion in various hospitals [17–19]. According to the report of Zhang HD et al. RBCLS is not affected by gender or age [19]. Studies have reported the widespread application of this method in various diseases such as hereditary spherocytosis, rheumatoid arthritis, polycythemia vera, and multiple myeloma to measure RBCLS, as well as to assess the impact of iron overload on RBCLS in patients with myelodysplastic syndromes [20–24].
Previous research by Mei-qing Lei et al. has demonstrated that the detection of RBCLS using the CO breath test effectively differentiates between thalassemia and iron-deficiency anemia, as these conditions have distinct mechanisms of anemia [25]. Similarly, TTP is characterized by microangiopathic hemolytic anemia, whereas ITP with anemia is not. Therefore, we hypothesize that measuring RBCLS can also be used to differentiate between these two conditions. Such differentiation would be valuable for early diagnosis, treatment, and improved survival rates in TTP patients. Hence, the aim of this study was to determine whether RBCLS assessment with the automated CO breath test can serve as a differentiation index for TTP and ITP accompanied by anemia.
Materials and methods
Subjects
We conducted a project to promote the application of CO breath test for the auxiliary diagnosis of anemic diseases. Therefore, all anemic patients admitted to the hematology department of our hospital underwent RBCLS testing. This study is a retrospective analysis that included 23 consecutive patients with newly diagnosed TTP (11 males and 19 females; median age, 48 years; range:18–71 years) and 32 consecutive ITP patients with anemia (12 males and 20 females; median age, 44 years; range:19–77 years) who were enrolled at the Department of Hematology in the Second Affiliated Hospital of Chongqing Medical University between April 2021 and May 2023. All TTP patients had decreased plasma ADAMTS13 activity and met the 2020 International Society on Thrombosis and Hemostasis (ISTH) criteria for TTP [7]. ITP diagnosis was primarily based on the exclusion of other causes of thrombocytopenia and met the criteria outlined in ITP guidelines [11]. Anemia was defined as a hemoglobin (Hb) concentration of ≤12 g/dL in men and 11 g/dL in women [26]. It is important to emphasize that all patients with ITP accompanied by anemia have already ruled out the diagnosis of Evans syndrome. Thirty healthy subjects were included in the study. Patients with severe chronic cardiopulmonary diseases and those who had received blood transfusion within 3 weeks were excluded from this study. The study was conducted in accordance with the Declaration of Helsinki and ethics approval was obtained. Informed consent was obtained from all the participants. The characteristics of the study participants are summarized in .
Table 1. Characteristics of study subjects included in the study.
Sample collection
The test procedure was simple. Alveolar air samples were obtained according to the manufacturer’s instructions (ELS TESTER; Seekya Biological Technology Co., LTD, Shenzhen, China) [19]. CO breath tests were performed within 24 h without smoking on an empty stomach. In brief, each subject took a deep breath, held it for 10 s, and then exhaled into a collection system through a mouthpiece. The collection system automatically discarded the initial 300 ml of exhaled air and collected the succeeding alveolar air in a self-sealing foil bag. If required, the procedure was repeated until 1 L of alveolar air was collected. Atmospheric samples were gathered immediately after breath sampling. The alveolar air and atmospheric samples were stored at room temperature and analyzed immediately. Peripheral vein blood samples were collected on the same day as the alveolar air sampling to conduct complete blood count tests.
RBCLS analysis
RBCLS was measured using a commercial automated instrument (ELSTESTER, Seekya Biological Technology Co., LTD, Shenzhen, China) [19]. The RBCLS values were calculated using the following formula: RBCLS (days) = 1.380 × [Hb]/endo Pco, where [Hb] represents the hemoglobin concentration in g/l and endo Pco represents the endogenous alveolar CO concentration in ppm. The concentration of endogenous CO was determined by subtracting the background environmental CO from the alveolar CO. After inputting the Hb value obtained from the laboratory test and triggering the start button, the RBCLS was automatically calculated using the concentrations of endogenous CO and Hb.
Statistical analysis
RBCLS and other clinical values for the subjects are expressed as the means ± standard deviation. Data were compared between groups using ANOVA. Correlations between the RBCLS and other clinical parameters were calculated using Pearson’s correlation coefficient. Categorical variables were analyzed using the chi-squared test. Receiver operator characteristics (ROC) curve was used to determine the RBCLS, lactic dehydrogenase and reticulocytes for predicting the diagnosis of TTP. The DeLong test is used to compare differences between ROC curves. Statistical significance was set at P < 0.05.
Results
Subject characteristics
The characteristics of the patients and healthy controls are summarized in . All 23 patients with TTP were classified as iTTP, with ADAMTS13 activity levels below 10%, and positive ADAMTS13 antibodies. Among the 23 TTP patients, triggers were identified in 13 cases:6 patients had concurrent infections at the time of initial diagnosis, including 2 cases of COVID-19 infection, 3 patients developed TTP after vaccination, and 4 patients had underlying autoimmune disease. The primary manifestation of the 32 patients with ITP accompanied by anemia was skin and mucosal bleeding, with 12 patients experiencing gastrointestinal (GI) bleeding and 3 patients presenting with concomitant iron-deficiency anemia. With respect to hematological findings, both the TTP and ITP with anemia groups had significantly lower levels of hemoglobin and platelets than the control group. The TTP group had significantly lower hemoglobin level than the ITP with anemia group. Additionally, the TTP group showed significantly higher reticulocyte percentages, lactate dehydrogenase, and indirect bilirubin levels than both the healthy controls and ITP group accompanied by anemia ().
RBCLS in subjects
The RBCLS values in patients and healthy controls are shown in . The mean RBCLS was significantly shorter in TTP patients (20 ± 8 days) than in patients with ITP accompanied by anemia (77 ± 22 days, P < 0.001) and healthy controls (114 ± 25 days P < 0.001). Furthermore, the mean RBCLS was significantly shorter in patients with ITP accompanied by anemia compared to healthy controls. Moreover, within the ITP subgroup, the RBCLS in the 12 patients with GI bleeding (56 ± 13 days) was significantly shorter than that in the 20 patients without GI bleeding (90 ± 15 days, p < 0.001), while still being significantly longer than that in the TTP group (p < 0.001).
Figure 1. Scatter plots showing RBCLS for three groups. The mean RBCLS was found to be shorter in TTP patients (n = 23) compared to ITP patients accompanied by anemia (n = 32). Furthermore, the mean RBCLS was significantly shorter in patients with ITP accompanied by anemia compared to healthy controls (n = 30). Among ITP patients, those without gastrointestinal (GI) bleeding (n = 20) exhibited higher RBCLS values than those with GI bleeding (n = 12). Mean and SD are shown for each group. The long horizontal dashed line indicates baseline normal RBCLS. RBCLS: red blood cell lifespan, HC: healthy controls, ITP: primary immune thrombocytopenia, TTP: thrombotic thrombocytopenic purpura.
Correlation between RBCLS and clinical parameters
Considering the significantly shortened RBCLS in TTP patients, we conducted further analysis to examine the correlation between RBCLS and several important clinical parameters. The results of the correlation analysis revealed that RBCLS was not associated with sex, age, creatinine level, or percentage of schistocytes (data not shown). However, RBCLS exhibited a significant negative correlation with reticulocyte percentage and lactate dehydrogenase levels ().
Figure 2. Correlation between RBCLS and clinical laboratory indices in 23 TTP patients. A: RBCLS versus reticulocyte percentage; B: RBCLS versus lactic dehydrogenase level. RBCLS: red blood cell lifespan, TTP: thrombotic thrombocytopenic purpura.
Effect of RBCLS in distinguishing between TTP and ITP accompanied by anemia
The instrument's normal baseline value for RBCLS is ≥75 days. Our results showed that the RBCLS of all healthy controls exceeded the normal baseline value of 75 days, whereas all TTP patients had RBCLS below 75 days. Among patients with ITP accompanied by anemia, those with GI bleeding exhibited RBCLS below 75 days, while the majority of patients without GI bleeding had RBCLS above 75 days ().
A 75-day RBCLS cut-off value was used to differentiate between TTP and ITP accompanied by anemia. Using ≥75 days as a potential diagnostic criterion for ITP accompanied by anemia, our RBCLS results showed a sensitivity of 53.1% (17/32) and specificity of 100% (23/23). The positive predictive value was 100% (17/17 + 0), the negative predictive value was 60.5% (23/15 + 23), and the accuracy level was 72.7% (17 + 23/55). Similarly, using the RBCLS <75 days criterion as an indicator of TTP, the diagnostic accuracy, sensitivity, specificity, positive predictive value, and negative predictive value were 72.7%, 100%, 53.1%, 60.5%, and 100.0%, respectively. If ITP patients with GI bleeding were excluded, the accuracy of RBCLS in diagnosing TTP could be improved to 93% (17 + 23/43).
In addition to using a 75-day cut-off value to differentiate between TTP and ITP with anemia, we also evaluated the predictive capability of RBCLS for TTP outcomes and compared it with lactic dehydrogenase and reticulocytes using ROC curve. The area under the ROC curve (AUC) for RBCLS was 0.985 (95% CI: 0–1, P < 0.01), with the optimal cut-off value of 32d, and sensitivity and specificity of 95.7% and 96.9%, respectively. The accuracy of predicting TTP with RBCLS was comparable and not inferior (P = 0.556) to that of lactic dehydrogenase (AUC = 0.973, 95% CI: 0–1, P < 0.01), but it was superior (p = 0.008) to that of reticulocytes (AUC = 0.867, 95% CI: 0.771–0.962, P < 0.01) ().
Figure 3. ROC curve for predicting TTP using RBCLS, LDH and RET. ROC: receiver operating characteristic, TTP: thrombotic thrombocytopenic purpura, LDH: lactate dehydrogenase, RET: reticulocyte.
Discussion
TTP is a life-threatening thrombotic microangiopathy, and it is crucial to differentiate rapidly between TTP and ITP accompanied by anemia. In this study, we utilized a CO breath test to detect RBCLS for differentiating between TTP and ITP accompanied by anemia. This test can be completed within a few minutes and offers the advantages of being fast, convenient, and easily applicable. Our findings showed that when using a normal baseline value of 75 days as a predictive value for diagnosis, the accuracy, sensitivity, and specificity of RBCLS in diagnosing TTP were 72.7%, 100%, and 53.1%, respectively. Additionally, the accuracy can be improved to 93% when the interference of GI bleeding is excluded. Furthermore, ROC curve analysis was utilized to assess the predictive capability of RBCLS for TTP, yielding an AUC of 0.985. The optimal cut-off value was identified as 32 days, with sensitivity and specificity rates of 95.7% and 96.9%, respectively. Therefore, our study suggests that RBCLS measurement can serve as an important differentiating marker for TTP and ITP accompanied by anemia. This study is the first to report RBCLS as a distinguishing parameter between TTP and ITP accompanied by anemia.
Our study revealed that healthy subjects have a mean RBCLS of 114 ± 25 days, which is consistent with previous reports using both traditional and CO methods [21,27]. Significant differences were detected in RBCLS between patients with TTP and ITP accompanied by anemia, attributed to their diverse pathophysiological mechanisms contributing to anemia. In TTP, the mechanism of anemia is microangiopathic hemolytic anemia, where RBCs are squeezed, deformed, and ruptured as they pass through intravascular microthrombi [28]. This process leads to a shortened RBCLS. However, in patients with ITP accompanied by anemia, the predominant mechanism of anemia was hemorrhagic anemia, which manifested primarily as skin and mucosal bleeding. Specifically, 12 ITP patients in our study experienced GI bleeding. We found that all ITP patients with GI bleeding had an RBCLS below 75 days. Previous reports have indicated that GI bleeding can impact the results of the CO breath test [25]. The destruction of RBCs in the GI tract can lead to an increase in endogenous CO concentration, resulting in false-positive results. Therefore, we recommend that when using a CO breath test to detect RBCLS as an auxiliary analysis for determining the cause of anemia, it is necessary to first carefully assess the patient's clinical presentation and perform a fecal occult blood test to confirm the presence of GI bleeding and evaluate the potential impact on the results. Our results also indicated that by setting an optimal threshold of 32 days, RBCLS can forecast the sensitivity and specificity of TTP without excluding GI bleeding at 95.7% and 96.9%, respectively. Consequently, a lower threshold of 32 days may be employed for discrimination.
TTP can be caused by either an inherited severe deficiency of plasma ADAMTS13 activity due to mutations in ADAMTS13 or immune-mediated through the presence of autoantibodies that inhibit plasma ADAMTS13 activity. In our study, all 23 adult patients were classified as having iTTP based on positive ADAMTS13 antibodies. 13 patients were diagnosed with underlying conditions, including infections such as COVID-19, vaccination, and autoimmune diseases. According to the ISTH guidelines, plasma exchange and immunosuppressive therapy can be initiated for suspected cases of iTTP to reduce mortality in life-threatening situations, without waiting for ADAMTS13 activity and antibody results [29]. CO breath test can rapidly yield results for detecting RBCLS. When combined with other laboratory tests and clinical scores such as the PLASMIC score, it aids in promptly distinguishing suspected TTP and starting suitable treatment to enhance patient outcomes.
Important laboratory abnormalities observed in TTP patients include the presence of schistocytes in blood smears, an increased proportion of reticulocytes, elevated levels of serum lactate dehydrogenase, and varying degrees of elevated blood creatinine levels [30]. In our study, we found that RBCLS was not affected by factors such as sex, age, creatinine level, or schistocyte percentage. However, we observed a significant negative correlation between RBCLS and the percentage of reticulocytes as well as lactate dehydrogenase levels. When evaluating the predictive capability for TTP using ROC curves, our results indicate that RBCSL and lactate dehydrogenase are comparable and significantly better than reticulocytes. However, it is important to note that elevated lactate dehydrogenase levels can be seen in various conditions such as multiple malignancies, myocardial infarction, hepatitis, etc. When confronted with these scenarios collectively, relying on lactate dehydrogenase to distinguish hemolysis can pose a challenge. Nevertheless, it is worth mentioning that, the AUC for RBCSL and lactate dehydrogenase were 0.985 and 0.973, respectively. The 95% confidence intervals ranged from 0 to 1, indicating some uncertainty in the AUC estimates. This wide confidence interval is likely due to the small sample size. Nonetheless, our analysis showed a p-value of less than 0.01, indicating the significance of RBCSL and lactate dehydrogenase in distinguishing TTP and ITP accompanied by anemia. Further research with increased sample size is warranted to validate the results and improve the stability of AUC estimates.
Our study provides evidence that RBCLS can be a sensitive indicator for distinguishing TTP from ITP accompanied by anemia. However, it is important to note that RBCLS cannot differentiate TTP from Evans syndrome and other thrombotic microangiopathies since these conditions also involve acute hemolysis. To accurately differentiate these disorders, additional tests like the Coombs test, clinical scores, and ADAMTS13 activity results are required. Moreover, the limitations of this study include a small sample size and a lack of validation from our institute or another. These limitations may reduce the robustness of clinical findings. Nevertheless, the findings of this preliminary study are interesting and warrant further research.
Conclusions
The current study utilized a CO breath test to provide a simple and accessible means of evaluating RBCLS to differentiate TTP from ITP accompanied by anemia. We believe that this study holds promising clinical value in facilitating early diagnosis, treatment, and improvement in prognosis for TTP.
Statement of ethics
The study was approved by the ethics committee of the participating institutions. Written informed consent was obtained from the patients.
Disclosure statement
No potential conflict of interest was reported by the author(s).
Data availability statement
The datasets analyzed in this study can be requested from the corresponding author upon a reasonable request.
Additional information
Funding
References
- Mariotte E, Azoulay E, Galicier L, et al. Epidemiology and pathophysiology of adulthood-onset thrombotic microangiopathy with severe ADAMTS13 deficiency (thrombotic thrombocytopenic purpura): a cross-sectional analysis of the French national registry for thrombotic microangiopathy. Lancet Haematol. 2016;3(5):e237–245. doi:10.1016/S2352-3026(16)30018-7
- Reese JA, Muthurajah DS, Kremer Hovinga JA, et al. Children and adults with thrombotic thrombocytopenic purpura associated with severe, acquired Adamts13 deficiency: comparison of incidence, demographic and clinical features. Pediatr Blood Cancer. 2013;60(10):1676–1682. doi:10.1002/pbc.24612
- Staley EM, Cao W, Pham HP, et al. Clinical factors and biomarkers predict outcome in patients with immune-mediated thrombotic thrombocytopenic purpura. Haematologica. 2019;104(1):166–175. doi:10.3324/haematol.2018.198275
- Sukumar S, Lämmle B, Cataland SR. Thrombotic thrombocytopenic purpura: pathophysiology, diagnosis, and management. J Clin Med. 2021;10(3). doi:10.3390/jcm10030536
- Cohen CT, Zobeck M, Kim TO, et al. Adolescent acquired thrombotic thrombocytopenic purpura: An analysis of the pediatric health information system database. Thromb Res. 2023;222:63–67. doi:10.1016/j.thromres.2022.12.011
- Levy GG, Nichols WC, Lian EC, et al. Mutations in a member of the ADAMTS gene family cause thrombotic thrombocytopenic purpura. Nature. 2001;413(6855):488–494. doi:10.1038/35097008
- Zheng XL, Vesely SK, Cataland SR, et al. ISTH guidelines for the diagnosis of thrombotic thrombocytopenic purpura. J Thromb Haemost. 2020;18(10):2486–2495. doi:10.1111/jth.15006
- Caocci G, Mulas O, Mantovani D, et al. Safety and efficacy of caplacizumab retreatment in a real-life monocentric cohort of patients with immune-mediated thrombotic thrombocytopenic purpura. Thromb Res. 2023;228:189–190. doi:10.1016/j.thromres.2023.06.018
- Page EE, Kremer Hovinga JA, Terrell DR, et al. Thrombotic thrombocytopenic purpura: diagnostic criteria, clinical features, and long-term outcomes from 1995 through 2015. Blood Adv. 2017;1(10):590–600. doi:10.1182/bloodadvances.2017005124
- Soares Ferreira Junior A, Pinheiro Maux Lessa M, Boyle SH, et al. In patients with suspected immune TTP, admission source impacts hospital length of stay and time to therapeutic plasma exchange impacts clinical outcomes. Thromb Res. 2023;227:34–39. doi:10.1016/j.thromres.2023.05.001
- Provan D, Arnold DM, Bussel JB, et al. Updated international consensus report on the investigation and management of primary immune thrombocytopenia. Blood Adv. 2019;3(22):3780–3817. doi:10.1182/bloodadvances.2019000812
- Bendapudi PK, Hurwitz S, Fry A, et al. Derivation and external validation of the PLASMIC score for rapid assessment of adults with thrombotic microangiopathies: a cohort study. Lancet Haematol. 2017;4(4):e157–e164. doi:10.1016/S2352-3026(17)30026-1
- Domingo-González A, Regalado-Artamendi I, Martín-Rojas RM, et al. Application of the French TMA reference center score and the mortality in TTP score in de novo and relapsed episodes of acquired thrombotic thrombocytopenic purpura at a tertiary care facility in Spain. J Clin Apher. 2021;36(3):420–428. doi:10.1002/jca.21880
- Fage N, Orvain C, Henry N, et al. Proteinuria increases the PLASMIC and French scores performance to predict thrombotic thrombocytopenic purpura in patients with thrombotic microangiopathy syndrome. Kidney Int Rep. 2022;7(2):221–231. doi:10.1016/j.ekir.2021.11.009
- Saha M, McDaniel JK, Zheng XL. Thrombotic thrombocytopenic purpura: pathogenesis, diagnosis and potential novel therapeutics. J Thromb Haemost. 2017;15(10):1889–1900. doi:10.1111/jth.13764
- Franco RS. Measurement of red cell lifespan and aging. Transfus Med Hemother. 2012;39(5):302–307. doi:10.1159/000342232
- Coburn RF. The measurement of endogenous carbon monoxide production. J Appl Physiol. 2012;112(11):1949–1955. doi:10.1152/japplphysiol.00174.2012
- Furne JK, Springfield JR, Ho SB, et al. Simplification of the end-alveolar carbon monoxide technique to assess erythrocyte survival. J Lab Clin Med. 2003;142(1):52–57. doi:10.1016/S0022-2143(03)00086-6
- Zhang HD, Ma YJ, Liu QF, et al. Human erythrocyte lifespan measured by Levitt's CO breath test with newly developed automatic instrument. J Breath Res. 2018;12(3):036003. doi:10.1088/1752-7163/aaacf1
- Shi Y, Li Y, Yang X, et al. Genotype-degree of hemolysis correlation in hereditary spherocytosis. BMC Genomics. 2023;24(1):304. doi:10.1186/s12864-023-09364-8
- Mitlyng BL, Singh JA, Furne JK, et al. Use of breath carbon monoxide measurements to assess erythrocyte survival in subjects with chronic diseases. Am J Hematol. 2006;81(6):432–438. doi:10.1002/ajh.20644
- Gao QY, Zhu YM, Hu J, et al. [Red blood cell lifespan detected by endogenous carbon monoxide breath test in patients with polycythemia vera]. Zhonghua Nei Ke Za Zhi. 2019;58(10):777–781.
- Wang Y, Zhang Z, Liu Y, et al. Use of carbon monoxide breath test to assess red blood cell lifespan in newly diagnosed multiple myeloma patients. J Breath Res. 2019;13(4):046008. doi:10.1088/1752-7163/ab2c12
- Zhang Y, Qian Y, Song LX, et al. The use of carbon monoxide breath test to detect the effect of iron overload on erythrocyte lifespan in MDS. Front Oncol. 2022;12:1058482. doi:10.3389/fonc.2022.1058482
- Lei MQ, Sun LF, Luo XS, et al. Distinguishing iron deficiency anemia from thalassemia by the red blood cell lifespan with a simple CO breath test: a pilot study. J Breath Res. 2019;13(2):026007. doi:10.1088/1752-7163/aafe4f
- Cappellini MD, Motta I. Anemia in clinical practice-definition and classification: does hemoglobin change with aging? Semin Hematol. 2015;52(4):261–269. doi:10.1053/j.seminhematol.2015.07.006
- Dinant HJ, de Maat CE. Erythropoiesis and mean red-cell lifespan in normal subjects and in patients with the anaemia of active rheumatoid arthritis. Br J Haematol. 1978;39(3):437–444. doi:10.1111/j.1365-2141.1978.tb01114.x
- Thomas MR, Scully M. How I treat microangiopathic hemolytic anemia in patients with cancer. Blood. 2021;137(10):1310–1317. doi:10.1182/blood.2019003810
- Zheng XL, Vesely SK, Cataland SR, et al. ISTH guidelines for treatment of thrombotic thrombocytopenic purpura. J Thromb Haemost. 2020;18(10):2496–2502. doi:10.1111/jth.15010
- Joly BS, Coppo P, Veyradier A. Thrombotic thrombocytopenic purpura. Blood. 2017;129(21):2836–2846. doi:10.1182/blood-2016-10-709857