Secondary causes of elevated hemoglobin in patients undergoing molecular testing for suspected polycythemia vera in southwestern Ontario: a chart review

Diagnosis, management, and outcomes of drug-induced erythrocytosis: a systematic review

ABSTRACT

Secondary erythrocytosis refers to an elevation in hemoglobin or hematocrit due to elevated serum erythropoietin levels. Medications including testosterone and sodium-glucose cotransporter-2 (SGLT-2) inhibitors are increasingly recognized as causes of secondary erythrocytosis. We conducted a systematic review to inform the clinical management of drug-induced erythrocytosis. Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, we performed a systematic literature search in MEDLINE, EMBASE, CENTRAL (all via Ovid), and Google Scholar. Of the 2036 articles screened for eligibility, 45 studies were included in our review, with 35 studies on testosterone and other androgen use, 5 studies on SGLT-2 inhibitors, 3 studies on antiangiogenic tyrosine kinase inhibitors (TKIs), 1 study on erythropoiesis-stimulating agents, and 1 study on a treatment regimen for multidrug-resistant tuberculosis. Cisgender and transgender men on prescription testosterone had erythrocytosis rates of up to 66.7%, with intramuscular formulations, higher doses, and older age associated with increased risk of erythrocytosis. Up to 2.7% of men on testosterone therapy developed thromboembolic events. Among individuals on SGLT-2 inhibitors, erythrocytosis rates ranged from 2.1% to 22%, with those who discontinued therapy demonstrating improvement or resolution of erythrocytosis. Thromboembolic events were reported in up to 10% of these individuals. Antiangiogenic TKIs were studied in patients with cancer, with erythrocytosis developing in up to 43.5% of patients. Drug-induced erythrocytosis is a heterogeneous condition for which there is no clear consensus among clinicians about its diagnosis and management. We offer recommendations for clinical practice within the scope of this systematic review, although further research is required.

Prevalence and predictive factors of testosterone-induced erythrocytosis: a retrospective single center study

Aim

This study analyzes the prevalence and predictive factors of testosterone-induced erythrocytosis (TIE) in patients receiving testosterone replacement therapy (TRT).

Methods

Retrospective single-center observational study.

Results

247 patients were included; median age was 47.0 years (interquartile range (IQR) 32-60) and median follow-up years 2.9 (1.0-5.5). The most common indication for TRT was central hypogonadism (51%) followed by primary hypogonadism (26%). TRT was carried out with testosterone undecanoate (TU) n=194, testosterone enanthate (TE) n=18 and testosterone gel (n=35). Compared to baseline, hematocrit (HCT) values at last follow-up (LFU) increased significantly by +0.04 (95% confidence interval (CI) [0.027, 0.050], p=<0.0001) in all patients (n=92) and +0.06 (95%CI [0.031, 0.057], p<0.0001) in the TU group (n=71). 57% of the patients reached an HCT value>0.46, 23% >0.5 and 5%>0.54. 46% of the patients who have reached an HCT value >0.46 have had their highest HCT measurement within the first year of TRT application. Logistic regression analysis indicated that body mass index (BMI) was significantly associated with the development of an HCT ≥0.5 (p=0.013) and HCT ≥0.46 (p=0.008). There was an association between the baseline HCT measurement and the outcome of a HCT measurement ≥0.46 (p=0.025), patients with high starting values were more likely to develop TIE.

Conclusions

TIE appears to be frequent and does not only present within the first year of therapy which indicates a close follow-up of laboratory values within the first year followed by annual controls. Baseline BMI and baseline HCT measurement should be considered in risk stratification of TIE development.

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.

Dapagliflozin-Induced Erythrocytosis in Chronic Kidney Disease: A Rare Occurrence

Erythrocytosis, a rare adverse effect associated with sodium-glucose cotransporter 2 inhibitors (SGLT2i), has been reported in diabetic patients, but its occurrence in those with chronic kidney disease (CKD) remains underrecognized. Here, we present two cases of dapagliflozin-related erythrocytosis in diabetic patients with CKD, highlighting the need for increased awareness among clinicians. Despite the established efficacy of SGLT2i in managing type 2 diabetes mellitus (T2DM) and its cardiovascular benefits, erythrocytosis poses a potential complication, necessitating thorough understanding and monitoring. While the precise mechanism of SGLT2i-induced erythrocytosis remains unclear, hypotheses include hemoconcentration and modulation of iron metabolism. Notably, our cases demonstrate a rapid onset of erythrocytosis, possibly exacerbated by CKD, emphasizing the importance of vigilant hemoglobin monitoring, especially in CKD patients on SGLT2i therapy. Timely discontinuation of dapagliflozin resulted in a significant reduction in hemoglobin levels, underscoring the critical role of early intervention in preventing erythrocytosis-related complications. This report advocates for routine hematological evaluation in CKD patients treated with SGLT2i to promptly detect and manage erythrocytosis, enhancing patient safety and improving clinical outcomes.

An Approach to the Investigation of Thrombocytosis: Differentiating between Essential Thrombocythemia and Secondary Thrombocytosis

Background

Thrombocytosis is a common reason for referral to Hematology. Differentiating between secondary causes of thrombocytosis and essential thrombocythemia (ET) is often clinically challenging. A practical diagnostic approach to identify secondary thrombocytosis could reduce overinvestigation such as next generation sequencing (NGS) panel.

Methods and Results

All adult patients with thrombocytosis (≥450 × 109/L) who underwent molecular testing at a single tertiary care centre between January 1, 2018 and May 31, 2021 were evaluated. Clinical and laboratory variables were compared between patients with secondary thrombocytosis vs. ET. Clinical variables included smoking, thrombosis, splenectomy, active malignancy, chronic inflammatory disease, and iron deficiency anemia. Laboratory variables included complete blood count (CBC), ferritin, and myeloid mutations detected by NGS. The overall yield of molecular testing was 52.4%; 92.1% of which were mutations in JAK2, CALR, and/or MPL. Clinical factors predictive of ET included history of arterial thrombosis (p < 0.05); active malignancy, chronic inflammatory disease, splenectomy, and iron deficiency were associated with secondary thrombocytosis (p < 0.05). A diagnosis of ET was associated with higher hemoglobin, mean corpuscular volume (MCV), red cell distribution width (RDW), and mean platelet volume (MPV), while secondary thrombocytosis was associated with higher body mass index, white blood cells, and neutrophils (p < 0.01).

Conclusion

A practical approach to investigating patients with persistent thrombocytosis based on clinical characteristics such as active malignancy, chronic inflammatory disease, splenectomy, and iron deficiency may assist in accurately identifying patients more likely to have secondary causes of thrombocytosis and reduce overinvestigation, particularly costly molecular testing.

A Rational Approach to JAK2 Mutation Testing in Patients with Elevated Hemoglobin: Results from the JAK2 Prediction Cohort (JAKPOT) Study

BACKGROUND

Erythrocytosis, most often measured as an increase in hemoglobin and/or hematocrit, is a common reason for referral to internal medicine and hematology clinics and a rational approach is required to effectively identify patients with polycythemia vera while avoiding over-investigation.

AIM

We aimed to develop and validate a simple rule to predict JAK2 mutation positivity based on complete blood count parameters to aid in the diagnostic approach to patients referred for elevated hemoglobin.

SETTING

Internal medicine and hematology clinics at an academic tertiary referral center.

PARTICIPANTS

The JAK2 Prediction Cohort (JAKPOT), a large retrospective cohort (n = 901) of patients evaluated by internal medicine and hematology specialists for elevated hemoglobin.

DESIGN

JAK2 mutation analysis was performed in all patients and clinical and laboratory variables were collected. Patients were randomly divided into derivation and validation cohorts. A prediction rule was developed using data from the derivation cohort and tested in the validation cohort.

KEY RESULTS

The JAKPOT prediction rule included three variables: (i) red blood cell count >6.45×1012/L, (ii) platelets >350×109/L, and (iii) neutrophils >6.2×109/L; absence of all criteria was effective at ruling out JAK2-positivity with sensitivities 94.7% and 100%, and negative predictive values of 98.8% and 100% in the derivation and validation cohorts, respectively, with an overall low false negative rate of 0.4%. The rule was validated for three different methods of JAK2 testing. Applying this rule to our entire cohort would have resulted in over 50% fewer tests.

CONCLUSION

In patients with elevated hemoglobin, the use of a simple prediction rule helps to accurately identify patients with a low likelihood of having a JAK2 mutation, potentially limiting costly over-investigation in this common referral population.