Genetic predisposition to hypertension facilitates blood pressure elevation in hemodialysis patients treated with erythropoietin

The effect of erythropoiesis-stimulating agents on systolic and diastolic blood pressure in hemodialysis patients: A systematic review and meta-analysis of clinical trials

OBJECTIVE

Anemia is a common condition in end-stage renal disease (ESRD) patients. Erythropoiesis-stimulating agents (ESAs) are commonly used to treat anemia in these patients. However, concerns have been raised regarding their potential effects on blood pressure. This systematic review and meta-analysis aim to investigate the relationship between ESAs and changes in systolic and diastolic blood pressure in hemodialysis patients.

METHOD

This study is a systematic review and meta-analysis based on clinical trial studies published in various databases, including Web of Science, Cochrane Library, Science Direct, PubMed, Embase, Scopus, and Google Scholar, between 1980 and the end of 2022. We evaluated the quality of articles using the Jadad scale checklist and analyzed the data using Stata 15 software.

RESULTS

Our meta-analysis included 34 clinical trial studies. The results showed a significant increase in both systolic blood pressure (SBP) and diastolic blood pressure (DBP) after the consumption of ESAs compared to before consumption. The mean difference in SBP was 4.84mmHg (95% CI: 2.74-6.94; p-value<0.001) and in DBP was 4.69mmHg (95% CI: 2.67-6.71; p-value<0.001). No publication bias was observed. Our meta-regression analysis showed that sample size, quality assessment score, and geographical location of the study were significant factors related to observed heterogenicity in to mean difference of SBP (p-value≤0.20). For DBP, the sample size, quality assessment score and follow-up duration were significant variables (p-value≤0.20).

CONCLUSION

Based on the findings of our study, it appears that receiving ESAs is associated with a significant increase in both SBP and DBP in hemodialysis patients, with an increase of about 5mmHg.

Systolic and diastolic hypertension among patients on hemodialysis: Musings on volume overload, arterial stiffness, and erythropoietin

Hypertension among patients on hemodialysis is predominantly systolic (either isolated or combined with diastolic hypertension), whereas the scenario of isolated diastolic hypertension is rare and more common in younger patients. Uncontrolled hypertension that persists despite aggressive antihypertensive drug therapy is a reflection of the volume overload that is a prominent mediator of systolic and diastolic BP elevation. Clinical-trial evidence supports the notion that dry-weight probing is an effective strategy to improve BP control, even when overt clinical signs and symptoms of volume overload are not present. Accelerated arterial stiffness influences the patterns and rhythms of interdialytic ambulatory BP and is a major determinant of isolated systolic hypertension in hemodialysis. Posthoc analyses of the Hypertension in Hemodialysis patients treated with Atenolol or Lisinopril (HDPAL) trial, however, suggest that arterial stiffness does not make hypertension more resistant to therapy and is unable to predict the treatment-induced improvement in left ventricular hypertrophy. A combined strategy of sodium restriction, dry-weight adjustment, and antihypertensive medication use was effective in improving ambulatory BP control regardless of the severity of underlying arteriosclerosis in HDPAL. Other nonvolume-dependent mechanisms, such as erythropoietin use, appear to be also important contributors and should be taken into consideration, particularly in younger hemodialysis patients with diastolic hypertension. In this article, we explore the role of volume overload, arterial stiffness, and erythropoietin use as causes of systolic vs diastolic hypertension in patients on hemodialysis. We conclude with clinical practice recommendations and with a call for a "volume-first" approach when managing hemodialysis hypertension.

Erythropoietin and glucose homeostasis in women at varying degrees of future diabetic risk

AIMS/BACKGROUND

Recently, there has been considerable interest in the potential anti-diabetic effects of erythropoietin in animal models. It is not known, however, whether endogenous erythropoietin is associated with glucose regulation in humans.

METHODS

We evaluated the longitudinal relationship between endogenous erythropoietin at 3-months postpartum and glucose homeostasis at 12-months postpartum in a cohort of 229 women with varying degrees of glucose intolerance in their recent pregnancy, a model of the early natural history of pre-diabetes/diabetes. The women reflected the full spectrum of glucose tolerance in pregnancy from normal (n=63) to mildly abnormal (n=65) to gestational impaired glucose tolerance (n=46) to gestational diabetes (n=55), and hence a broad range of future diabetic risk.

RESULTS

At 3-months postpartum, there was no difference in serum erythropoietin between these 4 groups (p=0.22). After covariate adjustment, erythropoietin was not associated with beta-cell function, insulin sensitivity, or glycemia at either 3- or 12-months postpartum. On multiple linear regression analyses, however, erythropoietin at 3-months emerged as an independent predictor of both systolic (beta=0.51326, p=0.003) and diastolic blood pressure (beta=0.3321, p=0.01) at 12-months.

CONCLUSION

Endogenous erythropoietin is not associated with glucose homeostasis early in the natural history of metabolic disease, but may be relevant to vascular health.

Assessment and management of hypertension in patients on dialysis

Hypertension is common, difficult to diagnose, and poorly controlled among patients with ESRD. However, controversy surrounds the diagnosis and treatment of hypertension. Here, we describe the diagnosis, epidemiology, and management of hypertension in dialysis patients, and examine the data sparking debate over appropriate methods for diagnosing and treating hypertension. Furthermore, we consider the issues uniquely related to hypertension in pediatric dialysis patients. Future clinical trials designed to clarify the controversial results discussed here should lead to the implementation of diagnostic and therapeutic techniques that improve long-term cardiovascular outcomes in patients with ESRD.

2008 Japanese Society for Dialysis Therapy: guidelines for renal anemia in chronic kidney disease

The Japanese Society for Dialysis Therapy (JSDT) guideline committee, chaired by Dr Y. Tsubakihara, presents the Japanese guidelines entitled "Guidelines for Renal Anemia in Chronic Kidney Disease." These guidelines replace the "2004 JSDT Guidelines for Renal Anemia in Chronic Hemodialysis Patients," and contain new, additional guidelines for peritoneal dialysis (PD), non-dialysis (ND), and pediatric chronic kidney disease (CKD) patients. Chapter 1 presents reference values for diagnosing anemia that are based on the most recent epidemiological data from the general Japanese population. In both men and women, hemoglobin (Hb) levels decrease along with an increase in age and the level for diagnosing anemia has been set at <13.5 g/dL in males and <11.5 g/dL in females. However, the guidelines explicitly state that the target Hb level in erythropoiesis stimulating agent (ESA) therapy is different to the anemia reference level. In addition, in defining renal anemia, the guidelines emphasize that the reduced production of erythropoietin (EPO) that is associated with renal disorders is the primary cause of renal anemia, and that renal anemia refers to a condition in which there is no increased production of EPO and serum EPO levels remain within the reference range for healthy individuals without anemia, irrespective of the glomerular filtration rate (GFR). In other words, renal anemia is clearly identified as an "endocrine disease." It is believed that defining renal anemia in this way will be extremely beneficial for ND patients exhibiting renal anemia despite having a high GFR. We have also emphasized that renal anemia may be treated not only with ESA therapy but also with appropriate iron supplementation and the improvement of anemia associated with chronic disease, which is associated with inflammation, and inadequate dialysis, another major cause of renal anemia. In Chapter 2, which discusses the target Hb levels in ESA therapy, the guidelines establish different target levels for hemodialysis (HD) patients than for PD and ND patients, for two reasons: (i) In Japanese HD patients, Hb levels following hemodialysis rise considerably above their previous levels because of ultrafiltration-induced hemoconcentration; and (ii) as noted in the 2004 guidelines, although 10 to 11 g/dL was optimal for long-term prognosis if the Hb level prior to the hemodialysis session in an HD patient had been established at the target level, it has been reported that, based on data accumulated on Japanese PD and ND patients, in patients without serious cardiovascular disease, higher levels have a cardiac or renal function protective effect, without any safety issues. Accordingly, the guidelines establish a target Hb level in PD and ND patients of 11 g/dL or more, and recommend 13 g/dL as the criterion for dose reduction/withdrawal. However, with the results of, for example, the CHOIR (Correction of Hemoglobin and Outcomes in Renal Insufficiency) study in mind, the guidelines establish an upper limit of 12 g/dL for patients with serious cardiovascular disease or patients for whom the attending physician determines high Hb levels would not be appropriate. Chapter 3 discusses the criteria for iron supplementation. The guidelines establish reference levels for iron supplementation in Japan that are lower than those established in the Western guidelines. This is because of concerns about long-term toxicity if the results of short-term studies conducted by Western manufacturers, in which an ESA cost-savings effect has been positioned as a primary endpoint, are too readily accepted. In other words, if the serum ferritin is <100 ng/mL and the transferrin saturation rate (TSAT) is <20%, then the criteria for iron supplementation will be met; if only one of these criteria is met, then iron supplementation should be considered unnecessary. Although there is a dearth of supporting evidence for these criteria, there are patients that have been surviving on hemodialysis in Japan for more than 40 years, and since there are approximately 20 000 patients who have been receiving hemodialysis for more than 20 years, which is a situation that is different from that in many other countries. As there are concerns about adverse reactions due to the overuse of iron preparations as well, we therefore adopted the expert opinion that evidence obtained from studies in which an ESA cost-savings effect had been positioned as the primary endpoint should not be accepted unquestioningly. In Chapter 4, which discusses ESA dosing regimens, and Chapter 5, which discusses poor response to ESAs, we gave priority to the usual doses that are listed in the package inserts of the ESAs that can be used in Japan. However, if the maximum dose of darbepoetin alfa that can currently be used in HD and PD patients were to be used, then the majority of poor responders would be rescued. Blood transfusions are discussed in Chapter 6. Blood transfusions are attributed to the difficulty of managing renal anemia not only in HD patients, but also in end-stage ND patients who respond poorly to ESAs. It is believed that the number of patients requiring transfusions could be reduced further if there were novel long-acting ESAs that could be used for ND patients. Chapter 7 discusses adverse reactions to ESA therapy. Of particular concern is the emergence and exacerbation of hypertension associated with rapid hematopoiesis due to ESA therapy. The treatment of renal anemia in pediatric CKD patients is discussed in Chapter 8; it is fundamentally the same as that in adults.

Hypertension induced by erythropoietin has a correlation with truncated erythropoietin receptor mRNA in endothelial progenitor cells of hemodialysis patients

Endothelial nitric oxide (NO) and cyclic guanosine monophosphate (cGMP) contribute to erythropoietin (EPO)-induced hypertension, a major adverse reaction associated with EPO therapy. To investigate the mechanism of EPO-induced hypertension, we examined circulating endothelial progenitor cells (EPCs) taken from 56 hemodialysis (HD) patients. Among these EPCs (which reflect the condition of the endothelium), we looked for EPO receptor (EPOR) mRNAs. A truncated form of EPOR acts as a dominant negative regulator of EPO signaling, leading to hypertension. We found that the ratio of truncated EPOR mRNA in EPCs has a correlation with EPO-induced increase in blood pressure (r = 0.36, P = 0.02). The ratio of truncated to total EPOR mRNA in EPCs had an inverse correlation with EPO-induced cGMP production in vitro (r = -0.31, P = 0.02). A similar correlation was observed in cultured human endothelial cells after transfection of the full-length or truncated forms of EPOR (r = -0.92, P < 0.001). It follows, therefore, that evaluation of EPOR isoform mRNA in EPCs can predict EPO-induced hypertension. The termination of the EPO signal by truncated EPORs may decrease NO/cGMP production after EPO exposure, thereby raising blood pressure.

Secondary hypertension due to drugs and toxins

This review summarizes the current state of knowledge about drugs, other chemical substances, and toxins on blood pressure. Many classes of drugs, such as steroids, sympathomimetic amines, immunosuppressive agents, nonsteroidal anti-inflammatory agents, antidepressants, erythropoietin, substances of abuse and other agents can induce transient or sustained hypertension, exacerbate well-controlled hypertension, antagonize the effects of antihypertensive therapy, or precipitate hypertensive emergencies. Heightened awareness on the part of the physician is important to avoid unnecessary tests in search for other etiologies, and to reduce antihypertensive medication prescriptions by eliminating contributing agents whenever possible. These agents represent an important modifiable cause of secondary or resistant hypertension.

2004 Japanese Society for Dialysis Therapy Guidelines for Renal Anemia in Chronic Hemodialysis Patients

The guideline committee of Japanese Society for Dialysis Therapy (JSDT), chaired by Professor F. Gejyo of Niigata University, now publishes an original Japanese guideline entitled 'Guidelines for Renal Anemia in Chronic Hemodialysis Patients'. It includes the re-evaluation of the usage of recombinant human erythropoietin (rHuEPO) with the medical and economical arguments regarding the prognosis and the quality of life of Japanese hemodialysis patients. This guideline consists of 7 sections. The first section comprises the general definition and the differential diagnosis of anemia. The hemoglobin (Hb) level of the Japanese population seemed to be low when compared with that of the European and American populations. The second section describes the target Hb level in hemodialysis patients. Multivariate analysis of the data that were collected from dialysis institutions throughout the country showed that an Hb level of 10-11 g/dL (Ht level 30-33%) at the first dialysis session in a week is the ideal range for chronic hemodialysis patients in terms of the 3-5 year survival rate. The supine position at blood sampling and the sampling timing at the first dialysis session in a week might affect the lower setting of target Hb hematocrit (Ht), compared to that of European and American guidelines. However, we particularly recommended that an Hb level of 11-12 g/dL (Ht level from 33 to 36%) at the first dialysis session in a week is desirable in relatively young patients. In the third section, the markers of iron deficiency are discussed. The Transferin saturation test (TSAT) and serum ferritin were emphasized as the standard markers. The routes of administration of rHuEPO and its dosages are written in the fourth section. The subcutaneous route was associated with the occurrence of secondary red cell aplasia due to anti-rHuEPO antibodies; however, secondary red cell aplasia was seldom observed in the venous injection. From this fact we recommend venous injection for chronic hemodialysis patients. We advocate an initial dosage of 1500 U three times per week. The fifth section deals with the factors refractory to treatment with rHuEPO. If the patient shows an inadequate response to the usage of 9000 U per week, this condition defines the inadequate response to rHuEPO in Japan. Blood transfusion must be avoided where possible. The reasons for this and the adverse effects are interpreted in section six. In the final section, the adverse effects of rHuEPO are listed. Among them, hypertension, thrombotic events and secondary red cell aplasia were emphasized as the major complications.

Biology of erythropoietin

Hypoxia induces tissue-specific gene products such as erythropoietin (EPO) and vascular endothelial growth factor (VEGF), which improve the peripheral O2 supply, and glucose transporters and glycolytic enzymes, which adapt cells to reduced O2 availability. EPO has been the fountainhead in research on pO2-dependent synthesis of proteins. The EPO gene enhancer (like the flanking DNA-elements of several other pO2-controlled genes) contains a consensus sequence (CGTG) that binds the trans-acting dimeric hypoxia-inducible factor 1 (HIF-1alpha/beta). The alpha-subunit of HIF-1 is rapidly degraded by the proteasome under normoxic conditions, but it is stabilized on occurrence of hypoxia. HIF-1 DNA-binding is also increased by insulin, and by interleukin-1 and tumor necrosis factor. Thus, in some aspects there is synergy in the cellular responses to hypoxia, glucose deficiency and inflammation. In viewing clinical medicine recombinant human EPO (rHu-EPO) has become the mainstay of treatment for renal anemia. Endogenous EPO and rHu-EPO are similar except for minor differences in the pattern of their 4 carbohydrate chains. RHu-EPO is also administered to patients suffering from non-renal anemias, such as in autoimmune diseases or malignancies. The correction of anemia in patients with solid tumors is not merely considered a palliative intervention. Hypoxia promotes tumor growth. However, the benefits of the administration of rHu-EPO to tumor patients with respect to its positive effects on tumor oxygenation, tumor growth inhibition and support of chemo- and radiotherapy is still debatable ground.

Hemodialysis-associated hypertension: pathophysiology and therapy

The majority of end-stage renal disease (ESRD) patients are hypertensive. Hypertension in the hemodialysis patient population is multifactorial. Further, hypertension is associated with an increased risk for left ventricular hypertrophy, coronary artery disease, congestive heart failure, cerebrovascular complications, and mortality. Antihypertensive medications alone do not adequately control blood pressure (BP) in hemodialysis patients. There are, however, several therapeutic options available to normalize BP in these patients, often without the need for additional drug therapy (eg, long, slow hemodialysis; short, daily hemodialysis; nocturnal hemodialysis; or, most effectively, dietary salt and fluid restriction in combination with reduction of dialysate sodium concentration). Optimal BP in dialysis patients is not different from recommendations for the general population, even though definite evidence is not yet available. Predialysis systolic and diastolic BPs are of particular importance. Left ventricular mass correlates with predialysis systolic BP. Survival is better in hemodialysis patients with a mean arterial pressure below 99 mm Hg as compared with those with higher BP. Low predialysis systolic BP (<110 mm Hg) and low predialysis diastolic BP (<70 mm Hg) are associated with increased mortality, primarily because of severe congestive heart failure or coronary artery disease. Patients that experience repeated intradialytic hypotensive episodes should also be viewed with caution, and predialytic BP values should be reevaluated. A possible treatment option for these patients may be slow, long hemodialysis; short, daily hemodialysis; or nocturnal hemodialysis. Among the antihypertensive agents currently available, angiotensin-converting enzyme (ACE) inhibitors appear to have the greatest ability to reduce left ventricular mass. Pressure load can be satisfactorily determined by using the average value of predialysis BP measurements over 1 month. In selected hemodialysis patients, interdialytic ambulatory blood pressure monitoring (ABPM) may help to determine if the patient is in fact hypertensive. In addition, ABPM provides important information about the change in BP between day and night. Regular home BP monitoring, yearly echocardiography, and treatment of traditional risk factors for cardiovascular disease are recommended.

Erythropoietin modulates angiotensin II- or noradrenaline-induced Ca(2+) mobilization in cultured rat vascular smooth-muscle cells

BACKGROUND

It has been reported that human recombinant erythropoietin (rHuEpo) modulates the sensitivity of the cardiovascular system to angiotensin II (Ang II) or noradrenaline (NA). In the present study, we explored the effect of rHuEpo on the responsiveness of Ang II- or NA-induced cytosolic free calcium ([Ca(2+)]i) mobilization in cultured rat vascular smooth-muscle cells (VSMC).

METHODS

[Ca(2+)]i concentrations in VSMC were measured by using the calcium-sensitive fluorescent dye fura-2.

RESULTS

The addition of rHuEpo (250 U/ml) alone induced elevation in [Ca(2+)]i, which remained significantly elevated above basal level for at least 60 min in the presence of extracellular Ca(2+). Pre-incubation with specific protein kinase C (PKC) inhibitor calphostin C (1 micromol/l) significantly reduced the peak and the sustained elevations of [Ca(2+)]i. Pre-treatment with rHuEpo for 60 min increased both basal [Ca(2+)]i and the changes in [Ca(2+)]i by Ang II or NA in a dose-dependent manner in the presence of extracellular Ca(2+). The synergistic effects of rHuEpo with Ang II or NA were also retained when VSMC were bathed in the Ca(2+)-free medium after the pre-incubation of rHuEpo. Conversely, they were diminished in the presence of extracellular Ca(2+) combined with intracellular Ca(2+) release inhibitor 8-(NN-diethylamino)octyl-1,3,4,5-trimethoxybenzoate (TMB-8). The synergistic effects of rHuEpo were also diminished by PKC depletion or by PKC inhibitor.

CONCLUSIONS

These observations suggest that rHuEpo has synergistic effects on Ang II- or NA-induced [Ca(2+)]i mobilization, particularly on intracellular Ca(2+) release, in VSMC. This may be a potential mechanism contributing to hypertension associated with rHuEpo therapy.

Normalization of hematocrit in hemodialysis patients with cardiac disease does not increase blood pressure

Since the earliest reports of the use of Epoetin alfa in hemodialysis patients, it has been described that Epoetin alfa may exacerbate preexisting hypertension or induce hypertension in End Stage Renal Disease (ESRD) patients not previously hypertensive. We undertook this study to determine if the correction of anemia in ESRD patients with cardiac disease from a hematocrit of 30+/-3% to 42+/-3% with the use of Epoetin alfa would result in increased blood pressure. This study was a substudy of the "Normal hematocrit Study".

METHODS

Thirty-one patients were randomized into one of two arms. Patients in Group A had their hematocrit increased with the use of slowly escalating doses of Epoetin alfa to 42+/-3% and patients in Group B were maintained with a hematocrit of 30+/-3% throughout the course of the study. All patients had their blood pressure recorded with a 24 hour ambulatory BP device at study entry and at 28 weeks following randomization when they had achieved their target hematocrit. Pre-dialysis systolic and diastolic BP was also recorded.

RESULTS

The mean hematocrit increased in Group A from 29.1+/-2.4% to 40.8+/-5.2% after 30 weeks. The hematocrit in Group B remained stable at 30+/-3% throughout the course of the study. There was no difference in mean daytime, mean nighttime or 24 hour systolic or diastolic blood pressure between Groups A and B at either baseline or follow-up. Neither was there a difference in mean pre-dialysis systolic or diastolic BP between Groups A or B at baseline or Follow-up. Four patients in Group A and 4 patients in Group B required an increase in their antihypertensive medication during the course of the study.

CONCLUSION

It is possible to increase hematocrit to normal levels in hemodialysis with the administration of Epoetin alfa. The increase in hematocrit from 30+/-3% to 42+/-3% is not associated with increased blood pressure.

Antiplatelet therapy decreases the incidence of erythropoietin-induced hypertension in predialysis patients

The observation that antiplatelet therapy may decrease the incidence of Epo-induced hypertension in dialysis patients remains a subject of particular interest. The aim of the present study was to test this hypothesis in patients at the predialysis stage. Predialysis patients with renal anemia were treated with EPO (6000 IU/week) for 6-12 months. Patients were divided into two groups, one of which received antiplatelet therapy and the other did not, and a comparison was made between them with respect to the incidence of EPO-induced hypertension. Logistic regression analysis was used to determine the risk factors for developing hypertension during the EPO therapy. Such predictors included age, gender, antecedent of hypertension, antiplatelet drugs and diabetes mellitus. Overall, 66 patients were enrolled in the study and 18 developed hypertension (27%). Out of the 35 patients not receiving antiplatelet therapy, 15 developed hypertension (43%). In contrast, out of the 31 patients receiving antiplatelet therapy, only 3 (10%) developed hypertension (p=0.003 by Chi square test). Multiple regression analysis showed that the best predictive variables for the development of hypertension were antecedent of hypertension (odds ratio: 0.064, p=0.0118), and use of antiplatelet drugs (odds ratio: 5.081, p=0.0295). The present data provide evidence that antiplatelet therapy may prevent EPO-induced hypertension in predialysis patients. However, the mechanism to explain such an effect still remains to be elucidated.

Endogenous erythropoietin correlates with blood pressure in essential hypertension

Patients on maintenance hemodialysis with a family history of essential hypertension are at higher risk for increased arterial blood pressure when treated with erythropoietin than patients without family history. This study was performed to elucidate the role of endogenous erythropoietin in essential hypertension. We conducted a study in 42 untreated patients (mean age, 51 +/- 9 years) with essential hypertension World Health Organization stages I or II. Ambulatory 24-hour blood pressure (Spacelab 90207), cardiac output (2D guided M-mode echocardiography and CW Doppler sonography), renal hemodynamics (para-aminohippurate and inulin clearance), and endogenous erythropoietin (radioimmunoassay) together with erythrocyte count, hemoglobin, and hematocrit were measured in parallel. Mean 24-hour systolic blood pressure was 145 +/- 13 mm Hg, and mean diastolic blood pressure was 93 +/- 8 mm Hg. The average erythropoietin concentration was 15.3 +/- 3.7 mU/mL and within the normal range. We found that the higher erythropoietin concentrations, the more elevated was both 24-hour ambulatory systolic (r = 0.51, P < 0.005) and diastolic blood pressure (r = 0.49, P < 0.005). Also, the concentration of endogenous erythropoietin was correlated with total peripheral resistance as noninvasively determined by echocardiographic and Doppler sonographic measurements (r = 0.40, P < 0.02 and r = 0.49, P < 0.02, respectively). With increasing erythropoietin concentrations, renal plasma flow and renal blood flow were found to be progressively reduced (r = -0.32, P < 0.05 and r = -0.35, P < 0.05, respectively) and renal vascular resistance increased (r = 0.41, P < 0.01). Neither hematocrit nor hemoglobin nor erythrocyte count were related to endogenous erythropoietin concentrations. In human essential hypertension, the level of arterial blood pressure is related to endogenous erythropoietin, which is hemodynamically mediated by an increase of total peripheral resistance. Because erythropoietin has shown proliferative and vasoconstricting effects on the endothelium in experimental studies, we suggest that endogenous erythropoietin might be an aggravating or even a promoting factor in the pathogenesis of essential hypertension.