Post-transplantation erythrocytosis in kidney transplant recipients-A retrospective cohort study

A systematic review and meta-analysis of factors contributing to post-kidney transplant anemia and the effect of erythropoietin-stimulating agents

BACKGROUND

The effects of various risk and associated factors on post-kidney transplant anemia (PTA) have not been fully compared and estimated. This meta-analysis aims to elucidate factors contributing to PTA and determine the influence of erythropoietin-stimulating agents (ESAs) on renal outcomes, thus offering potential pathways for enhanced management strategies post-transplant.

METHODS

A systematic review was conducted in electronical database. Studies reporting on risk factors (with cause-effect relationships) and associated factors (without definite cause-effect relationships) of PTA, and the effects of ESAs on post-kidney transplant outcomes, were included. Pooled odds ratios (ORs) and weighted mean differences (WMDs) were analyzed using random-effects models.

RESULTS

This systematic review encompassed 38,233 patients from 85 studies. Factors increased PTA risk included African American, older donor age, human antigen leukocyte mismatches, and low pre-transplant hemoglobin levels. Poor allograft function, high interleukine-6, Cytomegalovirus, delayed graft function, allograft rejections, immunosuppressive medications, and renin-angiotensin system blockades were associated with PTA. Native autosomal dominant polycystic kidney disease was a protective factor against PTA. Administration of ESAs with the aim of normalizing hemoglobin levels in patients with chronic allograft dysfunction slowed the decline in eGFR and reduce the risk of death, with a pooled OR of 0.36 (95% CI: 0.14 to 0.89; p = 0.040).

CONCLUSIONS

The risks and associated factors for PTA have been elucidated, underscoring the need for individualized treatment approaches. Late ESA therapy, aimed at hemoglobin normalization, suggests a renal-protective effect and reduced mortality, which should be considered in the management of PTA.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42024545330.

Elevated hemoglobin levels in renal transplant recipients with polycystic kidney disease versus other etiologies: exploring mechanisms and implications for outcomes

BACKGROUND

Autosomal dominant polycystic kidney disease (ADPKD)-related end-stage kidney disease (ESKD) often necessitates transplantation. However, the impact of ADPKD on post-transplant outcomes, specifically hemoglobin levels, remains unknown.

METHODS

We retrospectively analyzed 513 Kidney Transplant Recipients (KTRs), of whom 81 had ESKD due to ADPKD (20 with pre-transplant native nephrectomy and 61 without). Hemoglobin levels were evaluated at multiple time intervals post-transplant.

RESULTS

Kidney transplant recipients with ADPKD vs. KTRs with ESKD due to other causes exhibited significantly higher hemoglobin levels in repeated measurement analysis. Multivariable analyses confirmed ADPKD as an independent predictor for elevated hemoglobin levels. In a multivariable logistic regression analysis, the odds for maximum hemoglobin > 15 mg/dL at 3-12 months post-transplant were more than twice as high in ADPKD patients vs. all the other KTRs (Odds Ratio [OR] 2.31, 95% Confidence Interval [CI] 1.3-4.13, p < 0.001). Pre-transplant native nephrectomy revealed a trend toward lower hemoglobin levels. Elevated hemoglobin levels were linked to improved estimated glomerular filtration rate (eGFR) at one year post-transplant. Patient survival was enhanced among KTRs with ADPKD compared to other ESKD causes.

CONCLUSIONS

Kidney transplant recipients with ADPKD exhibited elevated hemoglobin levels post-transplant, possibly due to prolonged native kidney erythropoietin production. These elevated hemoglobin levels were linked to improved outcomes, including allograft function and patient survival. Future research should further investigate the underlying mechanisms driving favorable ADPKD KTR outcomes.

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.

Incidence, Risk Factors, and Outcomes of Posttransplant Erythrocytosis Among Simultaneous Pancreas-Kidney Transplant Recipients

Background

Posttransplant erythrocytosis (PTE) is a well-known complication of kidney transplantation. However, the risk and outcomes of PTE among simultaneous pancreas-kidney transplant (SPKT) recipients are poorly described.

Methods

We analyzed all SPKT recipients at our center between 1998 and 2021. PTE was defined as at least 2 consecutive hematocrit levels of >51% within the first 2 y of transplant. Controls were selected at a ratio of 3:1 at the time of PTE occurrence using event density sampling. Risk factors for PTE and post-PTE graft survival were identified.

Results

Of 887 SPKT recipients, 108 (12%) developed PTE at a median of 273 d (interquartile range, 160-393) after transplantation. The incidence rate of PTE was 7.5 per 100 person-years. Multivariate analysis found pretransplant dialysis (hazard ratio [HR]: 3.15; 95% confidence interval [CI], 1.67-5.92; P < 0.001), non-White donor (HR: 2.14; 95% CI, 1.25-3.66; P = 0.01), female donor (HR: 1.50; 95% CI, 1.0-2.26; P = 0.05), and male recipient (HR: 2.33; 95% CI, 1.43-3.70; P = 0.001) to be associated with increased risk. The 108 cases of PTE were compared with 324 controls. PTE was not associated with subsequent pancreas graft failure (HR: 1.36; 95% CI, 0.51-3.68; P = 0.53) or kidney graft failure (HR: 1.16; 95% CI, 0.40-3.42; P = 0.78).

Conclusions

PTE is a common complication among SPKT recipients, even in the modern era of immunosuppression. PTE among SPKT recipients was not associated with adverse graft outcomes, likely due to appropriate management.

Is Erythrocytosis More Common After Simultaneous Pancreas Kidney Transplantation? A Single-Center Experience

Post-transplant erythrocytosis (PTE) is reported in 8% to 22% of kidney transplant recipients. Few studies have evaluated the prevalence of PTE in simultaneous kidney-pancreas transplantation (SPKT). This study aimed to evaluate the prevalence of PTE in a cohort of SPKT and same-donor single kidney transplant patients and find predictive factors for erythrocytosis development. A single-center retrospective cohort study was performed with 65 SPKT recipients and 65 same-donor single kidney transplant patients. Post-transplant erythrocytosis was defined as a hematocrit persistently >51% without a known cause of erythrocytosis. The PTE prevalence was 23.1% and was more frequent in SPKT patients than in single donor patients (38.5% vs 7.7%; P < .001). The mean time for PTE development was 11.2 ± 13.3 months. In the multivariate model, SPKT was the only predictor for PTE development. De novo hypertension was more frequent in the PTE group (P = .002), but there was no difference in stroke and pancreatic or kidney thrombosis occurrence. Post-transplant erythrocytosis is more common after SPKT than after single kidney transplantation. De novo hypertension was more frequent in the erythrocytosis group, but allograft thrombosis rates.

JAK2 unmutated erythrocytosis: 2023 Update on diagnosis and management

DISEASE OVERVIEW

JAK2 unmutated or non-polycythemia vera (PV) erythrocytosis encompasses a heterogenous spectrum of hereditary and acquired entities.

DIAGNOSIS

Foremost in the evaluation of erythrocytosis is the exclusion of PV through JAK2 (inclusive of exons 12-15) mutation screening. Initial assessment should also include gathering of previous records on hematocrit (Hct) and hemoglobin (Hgb) levels, in order to streamline the diagnostic process by first distinguishing longstanding from acquired erythrocytosis; subsequent subcategorization is facilitated by serum erythropoietin (Epo) measurement, germline mutation screening, and review of historical data, including comorbid conditions and medication list. Hereditary erythrocytosis constitutes the main culprit in the context of longstanding erythrocytosis, especially when associated with a positive family history. In this regard, a subnormal serum Epo level suggests EPO receptor mutation. Otherwise, considerations include those associated with decreased (high oxygen affinity Hgb variants, 2,3-bisphosphoglycerate deficiency, PIEZO1 mutations, methemoglobinemia) or normal oxygen tension at 50% Hgb saturation (P50). The latter include germline oxygen sensing pathway (HIF2A-PHD2-VHL) and other rare mutations. Acquired erythrocytosis commonly results from central (e.g., cardiopulmonary disease, high-altitude habitat) or peripheral (e.g., renal artery stenosis) hypoxia. Other noteworthy conditions associated with acquired erythrocytosis include Epo-producing tumors (e.g., renal cell carcinoma, cerebral hemangioblastoma) and drugs (e.g., testosterone, erythropoiesis stimulating agents, sodium-glucose cotransporter-2 inhibitors). Idiopathic erythrocytosis is an ill-defined terminology that presumes the existence of an increased Hgb/Hct level without an identifiable etiology. Such classification often lacks accounting for normal outliers and is marred by truncated diagnostic evaluation.

MANAGEMENT

Current consensus treatment guidelines are not supported by hard evidence and their value is further undermined by limited phenotypic characterization and unfounded concerns for thrombosis. We are of the opinion that cytoreductive therapy and indiscriminate use of phlebotomy should be avoided in the treatment of non-clonal erythrocytosis. However, it is reasonable to consider therapeutic phlebotomy if one were to demonstrate value in symptom control, with frequency determined by symptoms rather than Hct level. In addition, cardiovascular risk optimization and low dose aspirin is often advised.

FUTURE DIRECTIONS

Advances in molecular hematology might result in better characterization of "idiopathic erythrocytosis" and expansion of the repertoire for germline mutations in hereditary erythrocytosis. Prospective controlled studies are needed to clarify potential pathology from JAK2 unmutated erythrocytosis, as well as to document the therapeutic value of phlebotomy.