Idiopathic erythrocytosis: A diagnostic and management challenge with emerging areas for exploration.

Despite published algorithms for approaching the work-up of erythrocytosis, a significant proportion of patients are left with uncertainty as to its aetiology and prognosis. The term 'idiopathic erythrocytosis' (IE) is applied when known primary and secondary aetiologies have been ruled out. However, the assignment of secondary aetiologies is not always straightforward or evidence based, which can lead to misdiagnosis and heterogeneity in cohort studies. Furthermore, new studies have identified germline or somatic mutations that may affect prognosis. Epidemiological and cohort data are inconsistent as to whether IE increases the risk for complications such as arterial and venous thromboembolism, clonal transformation or comorbid conditions. Randomized trials assessing the role of phlebotomy for long-term management of IE have not been performed, so treatment remains a vexing problem for clinicians. Standardization of terminology and testing strategies, including comprehensive genetic screening in clinical research, are key to refining our understanding of IE.

Erythrocytosis and CKD: A Review.

Erythrocytosis or polycythemia is defined as an increase in red blood cell concentration above the age- and sex-specific normal levels. Unlike anemia, which is very common in patients with chronic kidney disease (CKD), erythrocytosis is less frequent but requires specific understanding by health care professionals in order to provide the best care. Erythrocytosis, especially when undiagnosed and untreated, can lead to serious thrombotic events and higher mortality. Classic causes of erythrocytosis associated with CKD include cystic kidney diseases, kidney or other erythropoietin-secreting neoplasms, high-altitude renal syndrome, overdosage of erythropoietin-stimulating agents, androgen therapy, heavy smoking, chronic lung disease, obstructive sleep apnea, IgA nephropathy, post-kidney transplant erythrocytosis, renal artery stenosis, and congenital etiologies. After ruling out the common acquired causes of erythrocytosis and/or in the presence of suggestive parameters, primary erythrocytosis or polycythemia vera (PV) should be considered, and patients should be screened for JAK2V617F somatic mutation. The newest entity inducing erythrocytosis is linked to the use of sodium/glucose cotransporter 2 (SGLT2) inhibitors that hypothetically activate hypoxia-inducible factor 2α (HIF-2α) and in some cases unmask PV. This Review focuses on the pathogenesis, renal manifestations and management of PV, the pathophysiology of erythrocytosis induced by SGLT2 inhibitors and the relevance of timely JAK2 mutation screening in these patients.

Are coagulation profiles in Andean highlanders with excessive erythrocytosis favouring hypercoagulability?

Chronic mountain sickness is a maladaptive syndrome that affects individuals living permanently at high altitude and is characterized primarily by excessive erythrocytosis (EE). Recent results concerning the impact of EE in Andean highlanders on clotting and the possible promotion of hypercoagulability, which can lead to thrombosis, were contradictory. We assessed the coagulation profiles of Andeans highlanders with and without excessive erythrocytosis (EE+ and EE-). Blood samples were collected from 30 EE+ and 15 EE- in La Rinconada (Peru, 5100-5300 m a.s.l.), with special attention given to the sampling pre-analytical variables. Rotational thromboelastometry tests were performed at both native and normalized (40%) haematocrit using autologous platelet-poor plasma. Thrombin generation, dosages of clotting factors and inhibitors were measured in plasma samples. Data were compared between groups and with measurements performed at native haematocrit in 10 lowlanders (LL) at sea level. At native haematocrit, in all rotational thromboelastometry assays, EE+ exhibited hypocoagulable profiles (prolonged clotting time and weaker clot strength) compared with EE- and LL (all P < 0.01). At normalized haematocrit, clotting times were normalized in most individuals. Conversely, maximal clot firmness was normalized only in FIBTEM and not in EXTEM/INTEM assays, suggesting abnormal platelet activity. Thrombin generation, levels of plasma clotting factors and inhibitors, and standard coagulation assays were mostly normal in all groups. No highlanders reported a history of venous thromboembolism based on the dedicated survey. Collectively, these results indicate that EE+ do not present a hypercoagulable profile potentially favouring thrombosis.

TEMPI syndrome: difficult to diagnose, "easy" to treat?

TEMPI syndrome is a rare, acquired disorder with multisystemic manifestations. It is classified as a plasma cell disorder and is characterized by telangiectasias, erythrocytosis, monoclonal gammopathy, perinephric fluid collections and intrapulmonary shunt. Even though TEMPI's pathophysiology remains elusive, it responds to anti-myeloma therapy indicating that the monoclonal protein or clone plays a key role. We present a challenging case of a 73-year-old man with erythrocytosis and deteriorating renal function with nephrotic-range proteinuria in whom after extensive work up, the diagnosis of TEMPI syndrome was made. He was received treatment with daratumumab-bortezomib-cyclophosphamide and dexamethasone (Dara-VCD) and achieved a hematological and clinical response. We also report preliminary data on a multiplex assay for cytokines and growth factors for two patients with TEMPI syndrome and note lower levels for non-specific innate immunity related cytokines. A direct link between renal impairment and TEMPI syndrome is not currently established; cytokine deregulation could potentially be involved in the ischemic changes observed in the renal biopsy of our patient.

TEMPI syndrome: A clinical, light-microscopic and phenotypic evaluation with review of the literature.

BACKGROUND AND OBJECTIVES: TEMPI (telangiectasias, elevated erythropoietin and erythrocytosis, monoclonal gammopathy, perinephric fluid collections, and intrapulmonaryshunting) syndrome is a rare multisystemic disease classified as a monoclonal gammopathy of cutaneous significance. The pathogenesis and etiology of TEMPIare not well known because of the rarity of this disorder. Although telangiectasias are the hallmark of this syndrome, skin biopsies are rarely performed. We aim to further characterize TEMPI syndrome through the evaluationof a skin biopsy. METHODS: We reviewed the histopathology and immunophenotypic profile of a skin biopsy from a 53-year-oldwoman diagnosed with TEMPI syndrome. Other components of her syndromic complex included an IgA myeloma, elevated vascular endothelial growth factor (VEGF), and erythrocytosis. RESULTS: A biopsy showed prominent vascular ectasia with some degree of microvascular basement membranezone thickening. Our patient had a reduction in neoplastic plasma cell burdenand clearing of her telangiectasias following myeloma directed treatment. CONCLUSIONS: TEMPI can beviewed as a reactive vascular paraneoplastic syndrome in the setting of a plasma cell dyscrasia. Elaboration of VEGF from neoplastic plasma cells is likely pathogenetically implicated and appears to be a common link that explains other vascular lesions associated with monoclonal gammopathy syndromes.

Increased risk of erythrocytosis in men with type 2 diabetes treated with combined sodium-glucose cotransporter-2 inhibitor and testosterone replacement therapy.

PURPOSE: In clinical trials, sodium-glucose cotransporter-2 inhibitors (SGLT-2i) and testosterone replacement therapy (TRT) were shown to stimulate red blood cell production. Little is known if combination therapy poses risk of erythrocytosis in real world clinical practice. METHODS: This was a retrospective nationwide cohort study of US Veterans with type 2 diabetes (T2D) and baseline hematocrit between 38 and 50% who were prescribed SGLT-2i and/or TRT between 3/2013 and 10/2022 and had adequate adherence based on the proportion of days covered > 80%. Patients were divided into 3 groups: SGLT-2i only, TRT only, or combination therapy. Odds Ratio (OR) of new erythrocytosis defined as hematocrit level > 54% within 365 days of therapy initiation was calculated by logistic regression model adjusted for baseline hematocrit, age, BMI, obstructive sleep apnea, diuretic use, and smoking status. RESULTS: Of the entire cohort of 53,971 people with T2D, total of 756 (1.4%) patients developed erythrocytosis. In unadjusted analyses, the OR of new onset erythrocytosis was higher in the combined SGLT-2i and TRT group compared with the SGLT-2i or TRT group alone (4.99, 95% CI (3.10-7.71) and 2.91, 95% CI (1.87-4.31), respectively). In the models adjusted for baseline characteristics, patients on combination therapy had significantly higher odds of erythrocytosis compared to those on SGLT-2i (OR 3.80, 95% CI (2.27-6.11)) or TRT alone (OR 2.49, 95% CI (1.51-3.59)). Testosterone delivery route (topical vs injectable) did not modify increased odds of erythrocytosis. CONCLUSIONS: For the first time, we demonstrated that in large cohort of patients combined therapy with SGLT-2i and TRT is associated with increased erythrocytosis risk compared with either treatment alone. Given rising prevalence of SGLT-2i use, providers should consider periodic hematocrit assessment in persons receiving both SGLT-2i and TRT.

Chronic obstructive pulmonary disease burden, grades and erythrocytosis at a tertiary hospital in western Uganda.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is the third leading cause of death worldwide among people over 40 years of age, and erythrocytosis is one of the major complications associated with increased mortality among COPD patients. The study aimed to determine the proportion of COPD, associated factors, and the burden of erythrocytosis among COPD participants. METHODS AND MATERIALS: A descriptive cross-sectional study design was used. A consecutive sampling technique was used to obtain study participants at the Fort Portal Regional Referral Hospital outpatient clinic. Focused history and physical examination were carried out to select eligible participants. Participants were screened using the COPD population screener for spirometry after consenting to participate. The study enrolled all adults at risk of having COPD based on the COPD population screener and able to undergo spirometry. Spirometry was carried out according to the Global Chronic Obstructive Lung Disease and European Respiratory Society guidelines, and haemoglobin concentration was measured. RESULTS: One hundred eighty participants were enrolled in the study, most of whom were females. The modal and mean age of participants was 60 years with 139 (77.2%) females and primary as the highest education level 149(82.8%). The proportion of COPD was 25% (45) [95% CI 18.9 - 32] and highest among females (68.9%) and those aged 60 years and above (70%). The combined COPD assessment tool groups had a proportion of 55.6%, 37.8%, 4.4%, and 2.2% for groups A, B, C, and D, respectively. Age < 50 years was protective against COPD, while for every additional year of smoking, there was an associated 6.5% increased risk compared to the general population. Additionally, the proportion of erythrocytosis among COPD participants was 6.7%. CONCLUSIONS AND RECOMMENDATIONS: There was a high proportion of COPD among study participants (25%), with a 6.7% proportion of erythrocytosis. We recommend a complete blood count for every patient in groups C and D of the ABCD COPD GOLD groups.

Two Novel Genetic Variants Involved in the Oxygen Sensing Pathway in JAK2-unmutated Erythrocytosis.

JAK2-unmutated erythrocytosis or non-polycythemia vera erythrocytosis is a rare condition comprising both acquired and hereditary forms. Although acquired erythrocytosis has been well-studied, hereditary erythrocytosis remains poorly studied. Genetic alterations associated with hereditary erythrocytosis include mutations in erythropoietin receptor and erythropoietin (EPO), altered oxygen affinity mutations, and variants associated with the oxygen-sensing pathway. We established a molecular diagnostic approach based on these genes and retrospectively evaluated. Peripheral blood from 56 erythrocytosis patients, lacking JAK2 mutation, were screened for oxygen-sensing pathway abnormalities. Two novel mutations were identified in the EGLN1 gene: NM_022051.2:c.712G > C (p.Gly238Arg) and NM_022051.2:c.122A > C (p.Tyr41Ser) in two patients separately. Notably, both reported heterozygous mutations were absent in the population database. Predictions using multiple computer software indicated that these two missense mutations were harmful and induced a highly conserved amino acid change in EGLN1. Patients with the two mutations exhibited normal serum EPO levels and high hemoglobin and hematocrit levels. Additionally, three other variants of genes were identified in the oxygen-sensing pathway, including endothelial PAS domain protein 1 (EPAS1) rs184760160(2/56), and EGLN1 rs186996510(2/56), rs555121182(2/56). These variants were categorized as benign or likely benign. Our findings provide a framework for etiological research and highlight the importance of screening for genetic mutations associated with erythrocytosis in clinical practice.

[How I manage polycythemia]. / Comment j'explore une polyglobulie.

Polycythemia is suspected when hemoglobin and/or hematocrit levels exceed established norms based on gender and age. This biological anomaly can arise from a myeloproliferative neoplasm known as polycythemia vera, or be secondary to excess erythropoietin (EPO) or decreased in plasma volume. Faced with polycythemia, the search for JAK2 mutations and measurement of serum EPO levels can guide toward the etiology. In polycythemia vera, thromboembolic events are the most lethal complications and unfortunately often the initial manifestation of the disease. The condition can also progress to myelofibrosis or acute leukemia. Management aims at reducing the hematocrit below 45 %, in order to limit, but not completely prevent, thrombo-embolic complications. This article elaborates on the clinical considerations around this biological anomaly, relevant complementary examinations, and briefly the therapeutic management.

La polyglobulie est suspectée lorsque le taux d'hémoglobine et/ou d'hématocrite est au-dessus des normes définies selon le sexe et l'âge. Cette anomalie biologique peut survenir à la suite d'une néoplasie myéloproliférative appelée polycythemia vera (PV), être secondaire à un excès d'érythropoïétine (EPO) ou à une diminution du volume plasmatique. Face à une polyglobulie, la recherche de mutations du gène JAK2 et un dosage d'EPO sérique permettront d'orienter vers l'étiologie. En cas de PV, les phénomènes thrombo-emboliques sont les complications les plus léthales et sont malheureusement souvent la première manifestation de la maladie. La maladie peut également évoluer en myélofibrose ou en leucémie aiguë. La prise en charge vise à réduire le taux d'hématocrite en-dessous de 45 %, afin de limiter, sans les empêcher complètement, les complications thrombo-emboliques. Dans cet article, nous développons la réflexion clinique autour de cette anomalie biologique, les examens complémentaires pertinents dans ce domaine et, brièvement, la prise en charge thérapeutique.

Secondary Polycythemia and Non-Islet Cell Tumor-induced Hypoglycemia in Advanced Hepatocellular Carcinoma: A Case Report.

Continuously holding its position as the sixth most common cause of cancer and the third leading cause of cancer death, globally, Hepatocellular Carcinoma (HCC) remains as a healthcare priority. Production of various substances may result into systemic or metabolic complications, often known as paraneoplastic phenomena of HCC. A 56-year-old male with history of untreated chronic hepatitis B arrived with generalized weakness and intermittent headache in the last two days prior to admission. Laboratory findings demonstrated elevated hemoglobin (20.5 g/dl), alpha-fetoprotein (29,845 ng/dl), and d-Dimer (2,120 ng/ml) levels. Hypoglycemia (44 mg/dl) was documented with normal basal insulin level, confirming non-islet cell tumor hypoglycemia. Abdominal multiphasic CT-scan demonstrated a large solid lesion involving the whole right liver lobe, hyper-enhanced at arterial phase and wash-out pattern at venous and delayed phases, with portal vein thrombosis; thus, confirming HCC BCLC C. Further examinations revealed hypercellularity from bone marrow biopsy with the absence of JAK2 mutation. He underwent serial phlebotomy and received 80 mg acetylsalicylic acid orally, as well as cytoreductive agent to reduce the risk of thrombosis. Despite applications of different interventions, control of hypoglycemia could not be achieved without parenteral administration of high dextrose load. He was planned to receive oral multikinase inhibitor, however, he passed away due to severe hospital-acquired pneumonia. Paraneoplastic phenomena are common in HCC. Increased risk of blood hyper-viscosity and thrombosis attributed to polycythemia, as well as medical emergency resulting from hypoglycemia showed that both conditions should not be overlooked since they may worsen the patient's prognosis.

High-Altitude Erythrocytosis: Mechanisms of Adaptive and Maladaptive Responses.

Erythrocytosis, or increased production of red blood cells, is one of the most well-documented physiological traits that varies within and among in high-altitude populations. Although a modest increase in blood O2-carrying capacity may be beneficial for life in highland environments, erythrocytosis can also become excessive and lead to maladaptive syndromes such as chronic mountain sickness (CMS).

Novel perspectives regarding the physiologic mechanisms by which gliflozins induce reticulocytosis and erythrocytosis.

Gliflozins provide a breakthrough in the management of type-2 diabetes. In addition to facilitating normoglycemia, these sodium-glucose cotransporter type 2 (SGLT2) inhibitors attenuate obesity, hypertension, dyslipidemia, and fluid retention, reduce cardiovascular morbidity, retard the progression of renal dysfunction, and improve survival. The administration of gliflozins also triggers erythropoietin (EPO) production, with the consequent induction of reticulocytosis and erythrocytosis. The mechanism(s) by which gliflozins induce erythropoiesis is a matter of debate. Whereas the canonical pathway of triggering EPO synthesis is through renal tissue hypoxia, it has been suggested that improved renal oxygenation may facilitate EPO synthesis via noncanonical trails. The latter proposes that recovery of peritubular interstitial fibroblasts producing erythropoietin (EPO) is responsible for enhanced erythropoiesis. According to this hypothesis, enhanced glucose/sodium reuptake by proximal tubules in uncontrolled diabetes generates cortical hypoxia, with injury to these cells. Once transport workload declines with the use of SGLT2i, they recover and regain their capacity to produce EPO. In this short communication, we argue that this hypothesis is incorrect. First, there is no evidence for interstitial cell injury related to hypoxia in the diabetic kidney. Tubular, rather than interstitial cells are prone to hypoxic injury in the diabetic kidney. Moreover, hypoxia, not normoxia, stimulates EPO synthesis by hypoxia-inducible factors (HIFs). Hypoxia regulates EPO synthesis as it blocks HIF prolyl hydroxylases (that initiate HIF alpha degradation), hence stabilizing HIF signals, inducing HIF-dependent genes, including EPO located in the deep cortex, and its production is initiated by the apocrinic formation of HIF-2, colocalized in these same cells.

The Genomics and Genetics of Oxygen Homeostasis.

Human survival is dependent upon the continuous delivery of O2 to each cell in the body in sufficient amounts to meet metabolic requirements, primarily for ATP generation by oxidative phosphorylation. Hypoxia-inducible factors (HIFs) regulate the transcription of thousands of genes to balance O2 supply and demand. The HIFs are negatively regulated by O2-dependent hydrox-ylation and ubiquitination by prolyl hydroxylase domain (PHD) proteins and the von Hippel-Lindau (VHL) protein. Germline mutations in the genes encoding VHL, HIF-2α, and PHD2 cause hereditary erythrocytosis, which is characterized by polycythemia and pulmonary hypertension and is caused by increased HIF activity. Evolutionary adaptation to life at high altitude is associated with unique genetic variants in the genes encoding HIF-2α and PHD2 that blunt the erythropoietic and pulmonary vascular responses to hypoxia.

Elevated erythroferrone distinguishes erythrocytosis with inherited defects in oxygen-sensing pathway from primary familial and congenital polycythaemia.

Congenital erythrocytoses represent a heterogenous group of rare defects of erythropoiesis characterized by elevated erythrocyte mass. We performed molecular-genetic analysis of 21 Czech patients with congenital erythrocytosis and assessed the mutual link between chronic erythrocyte overproduction and iron homoeostasis. Causative mutations in erythropoietin receptor (EPOR), hypoxia-inducible factor 2 alpha (HIF2A) or Von Hippel-Lindau (VHL) genes were detected in nine patients, including a novel p.A421Cfs*4 EPOR and a homozygous intronic c.340+770T>C VHL mutation. The association and possible cooperation of five identified missense germline EPOR or Janus kinase 2 (JAK2) variants with other genetic/non-genetic factors in erythrocytosis manifestation may involve variants of Piezo-type mechanosensitive ion channel component 1 (PIEZO1) or Ten-eleven translocation 2 (TET2), but this requires further research. In two families, hepcidin levels appeared to prevent or promote phenotypic expression of the disease. No major contribution of heterozygous haemochromatosis gene (HFE) mutations to the erythrocytic phenotype or hepcidin levels was observed in our cohort. VHL- and HIF2A-mutant erythrocytosis showed increased erythroferrone and suppressed hepcidin, whereas no overproduction of erythroferrone was detected in other patients regardless of molecular defect, age or therapy. Understanding the interplay between iron metabolism and erythropoiesis in different subgroups of congenital erythrocytosis may improve current treatment options.

A novel germline hyperactivating JAK2 mutation L604F.

Somatic JAK2 mutations are the main molecular cause of the vast majority of polycythemia vera (PV) cases. According to a recent structural model, the prevalent acquired V617F mutation improves the stability of the JAK2 dimer, thereby enhancing the constitutive JAK2 kinase activity. Germline JAK2 mutations usually do not largely alter JAK2 signaling, although they may modulate the impact of V617F. We found an unusual germline JAK2 mutation L604F in homozygous form in a young PV patient, along with a low allele burden JAK2 V617F mutation, and in her apparently healthy sister. Their father with a PV-like disease had L604F in a heterozygous state, without V617F. The functional consequences of JAK2 L604Fmutation were compared with those induced by V617F in two different in vitro model systems: (i) HEK293T cells were transfected with plasmids for exogenous JAK2-GFP expression, and (ii) endogenous JAK2 modifications were introduced into HeLa cells using CRISPR/Cas9. Both mutations significantly increased JAK2 constitutive activity in transfected HEK293T cells. In the second model, JAK2 modification resulted in reduced total JAK2 protein levels. An important difference was also detected: as described previously, the effect of V617F on JAK2 kinase activity was abrogated in the absence of the aromatic residue F595. In contrast, JAK2 hyperactivation by L604F was only partially inhibited by the F595 change to alanine. We propose that the L604F mutation increases the probability of spontaneous JAK2 dimer formation, which is physiologically mediated by F595. In addition, L604F may contribute to dimer stabilization similarly to V617F.

Erythrocytosis and thrombotic events in kidney transplant recipients prescribed a sodium glucose cotransport-2 inhibitor.

INTRODUCTION: The safety and efficacy of sodium glucose cotransport-2 inhibitors (SGLT2i) in kidney transplant recipients remains uncertain. Transplant recipients may be at risk of thrombosis because of post-transplant erythrocytosis and SGLT2i are associated with an increase in hematocrit. METHODS: We determined SGLT2i use, the change in hematocrit and incidence of thrombotic events in kidney transplant recipients in 1700 prevalent patients in our center. RESULTS: Among the 42 patients treated with SGLT2i, the mean pre-transplant hematocrit was 31%, and none of the patients had a hematocrit ≥50%. The mean percent change in hematocrit measured at an average of 53 days after initiation of an SGLT2i was 11% and four patients (10%) had a hematocrit ≥ 50%. The mean hematocrit measured 3 months after treatment was 42% and two patients (5%) had a hematocrit ≥50%. One patient had a cerebellar stroke 14 months post-SGLT2i initiation when the hemoglobin was 173 grams/liter, and the hematocrit was 52%. CONCLUSIONS: All patients had a sustained increase in hematocrit 3 months after SGLT2i treatment. Hematocrit ≥50% occurred in 10%, and one patient had a thrombotic event that may or may not have been related to an increase in hematocrit. Clinicians may consider monitoring for erythrocytosis after starting and SGLT2i in kidney transplant recipients.

Erythrocytosis in Gender-Affirming Care With Testosterone.

PURPOSE: Gender-affirming hormone therapy (GAHT) is safe overall, with few adverse effects. One potential effect from using testosterone for GAHT is an increase in hemoglobin and/or hematocrit, known as secondary erythrocytosis. Current guidelines recommend monitoring hemoglobin or hematocrit routinely in the first year, some as frequently as every 3 months, which can create barriers to care. Our study explored the incidence of erythrocytosis in the first 20 months of testosterone therapy among people receiving gender-affirming care. METHODS: This is a descriptive fixed cohort study of hematocrit and hemoglobin data from the charts of 282 people taking testosterone for GAHT. RESULTS: During the first 20 months of testosterone therapy, the cumulative incidence of hematocrit >50.4% was 12.6%, hematocrit >52% was 1.0%, and hematocrit >54% was 0.6%. All people were taking injectable testosterone cypionate, with a median dose of 100 mg weekly. CONCLUSION: Severe erythrocytosis (hematocrit >54%) is a rare outcome of gender-affirming testosterone therapy. Clinical recommendations should reconsider the need for routine frequent erythrocytosis screening within the first year of testosterone therapy for patients who prefer to minimize laboratory draws.

"The Long Journey of Unexplained Erythrocytosis": Erythrocytosis due to High-Oxygen Affinity Hemoglobinopathy - Hemoglobin Variant Little Rock (HBB: c.432C>A) - A Report of a Swiss Family and Review of the Literature.

The differential diagnosis of erythrocytosis is complex, involving a tailored algorithm. Congenital causes are rare and such patients commonly face a long journey looking for diagnosis. This diagnosis requires expertise and accessibility to modern diagnostic tools. We present the case of a young Swiss man with long-standing erythrocytosis of unknown origin and his family. The patient had an episode of malaise as he went skiing above 2,000 m altitude. In the blood gas analysis, p50 was low (16 mm Hg) and erythropoietin was normal. Using next-generation sequencing, a mutation in the hemoglobin subunit beta gene was found, a pathogenic variant known as hemoglobin Little Rock causing high oxygen affinity. Some family members also had unexplained erythrocytosis, therefore the mutational status of the family was analyzed, the grandmother and mother showed the presence of the same mutation. The use of modern technology finally offered a diagnosis to this family.

Cardiovascular benefits of SGLT2 inhibitors in type 2 diabetes, interaction with metformin and role of erythrocytosis: a self-controlled case series study.

BACKGROUND: Sodium-glucose cotransporter-2 inhibitors (SGLT2i) have proven cardiovascular benefits in patients with type 2 diabetes (T2D). This self-controlled case series study aims to evaluate whether metformin use and SGLT2i-associated erythrocytosis influence its cardiovascular benefits. METHODS: T2D patients with metformin and/or SGLT2i prescriptions between 2015 and 2020 were identified from the Hong Kong population. Study outcomes were composite cardiovascular diseases (CVD), coronary heart disease (CHD), hospitalisation for heart failure (HHF), stroke, and erythrocytosis. Risk periods were patient-time divided into four mutually exclusive windows: (i) 'baseline period' of metformin use without SGLT2i; (ii) pre-SGLT2i period; (iii) exposure to SGLT2i without metformin; and (iv) exposure to the drug combination. Another SCCS model was applied to evaluate the association between erythrocytosis and cardiovascular outcomes regarding SGLT2i exposure. Four mutually exclusive risk periods included (i) SGLT2i exposure with erythrocytosis; (ii) SGLT2i exposure without erythrocytosis; (iii) absence of SGLT2i exposure with erythrocytosis; and (iv) absence of SGLT2i exposure without erythrocytosis. Incidence rate ratios (IRR) of events at different risk periods were estimated using conditional Poisson regression model. RESULTS: Among 20,861 patients with metformin and/or SGLT2i prescriptions, 2575 and 1700 patients with events of composite CVD and erythrocytosis were identified, respectively. Compared to metformin use without SGLT2i, SGLT2i initiation was associated with lower risks of composite CVD, CHD, and HHF-regardless of the presence (CVD: IRR = 0.43, 95% CI 0.37-0.51; CHD: IRR = 0.44, 95% CI 0.37-0.53; HHF: IRR = 0.29, 95% CI 0.22-0.40; all p < 0.001) and absence of concomitant metformin (CVD: IRR = 0.31, 95% CI 0.20-0.48; CHD: IRR = 0.38, 95% CI 0.25-0.59; HHF: IRR = 0.17, 95% CI 0.09-0.31; all p < 0.001); while SGLT2i was neutral on stroke risk. Compared to metformin-SGLT2i combination, exposure to SGLT2i alone was associated with comparable risks of all cardiovascular outcomes (all p > 0.05). Incidence rates of erythrocytosis at baseline, SGLT2i without and with metformin use periods were 0.75, 3.06 and 3.27 per 100 person-years, respectively. SGLT2i users who developed erythrocytosis had lower risk of HHF (IRR = 0.38, 95% CI 0.14-0.99, p = 0.049) than those who did not. CONCLUSIONS: Our real-world data suggested that SGLT2i-associated cardiovascular benefits were not attenuated by metformin use. Further studies will delineate the role of erythrocytosis as a surrogate marker of SGLT2i-associated cardiovascular benefit in reducing HHF.

Breaking Stereotypes: Polycythemia Secondary to Shisha Smoking in a Middle-Age Swiss Woman.

The diagnosis of polycythemia, particularly the secondary forms, can be challenging. The distinction between primary and secondary polycythemia is relevant and has management implications. A systematic diagnostic workup algorithm and a good anamnesis are of paramount relevance. More than one cause may be involved in the development of polycythemia, identifying all of them will be the key to better understanding and eventually solving the polycythemia. We describe a case of a 53-year-old Swiss woman with polycythemia and a high level of carboxyhemoglobin. Her medical story included obesity and obstructive sleep apnea. The anamnesis ruled out the habit of smoking cigarettes; however, the patient reported that she was on a trip to Egypt 10 years before and bought herself a shisha; since then, she used to smoke shisha daily, at home, alone. After drastically reducing and then stopping the shisha smoking, 7 months later her blood count and carboxyhemoglobin completely normalized.