Blunted erythropoietin response to anemia in patients with Type 1 diabetes

Serum erythropoietin concentration and its correlation with stage of diabetic retinopathy

BACKGROUND

Erythropoietin (EPO) is one of the systemic angiogenic factors, and its role in ocular angiogenesis and in diabetic retinopathy (DR) is not yet fully understood. The latest research data reveal a possible correlation of higher erythropoietin concentrations in the blood and in the eye with the development of more advanced stages of DR. The main aim of this work was to examine the possible influence of serum concentrations of erythropoietin on the development of diabetic retinopathy in patients with diabetes mellitus type 2.

METHODS

The research involved 90 patients examined at the University Eye Clinic of the Clinical Center of Vojvodina, Novi Sad, Serbia. The first group comprised 60 patients with diabetes mellitus lasting for 10 years or more, with diabetic retinopathy. The second, control group consisted of 30 healthy individuals. In the first group of 60 patients with diabetes, 30 of them had non-proliferative diabetic retinopathy (NPDR), and 30 had proliferative diabetic retinopathy (PDR). Laboratory EPO serum levels were determined, and they were correlated to the stage of DR. Concentration of EPO was assessed by ELISA method.

RESULTS

The highest average concentration of EPO in serum (9.95 mIU/ml) was determined in the group of people with diabetes with PDR. The lowest average concentration of EPO in the serum (6.90 mIU/ml) was found in the control group. The average concentration of EPO in serum in the group of patients with diabetes with NPDR was 7.00 mIU/ml. The EPO concentration in serum was elevated in the group of PDR, and it was directly proportional to the level of the clinical stadium of PDR, being significantly higher in the moderate and severe subgroup of PDR comparing to the control healthy subjects, NPDR and mild PDR (p = 0.007).

CONCLUSIONS

Significantly elevated serum concentration of EPO in the advanced stages of DR, and positive correlation between EPO serum concentration and clinical stages of PDR, suggest that erythropoietin represents an important growth factor from blood, which plays a significant role in retinal ischemia and angiogenesis in diabetic retinopathy, especially in the proliferative stage of this disease.

Markers of Anemia in Children with Type 1 Diabetes

AIM

The aim of the study was to assess markers of anemia in type 1 diabetes (T1D) children, compare them to results obtained in the control group, and estimate their relation to BMI SDS.

METHODS

94 (59% ♀) T1D children without other autoimmune disorders, aged 12.5 ± 4.1 years, T1D duration: 4.2 ± 3.6 years, HbA1c 7.3 ± 1.5% (57 ± 12.6 mmol/mol). Sex- and age-matched controls (43 children). In all children, anthropometric measurements, the blood count, iron turnover parameters, and vitamin B12 concentration were taken.

RESULTS

T1DM children had significantly higher red cell distribution width (RDW) (13.6 versus 12.6%; p < 0.001), hepcidin (0.25 versus 0.12 ng/ml; p < 0.001), and vitamin B12 concentrations (459 versus 397 pg/ml; p < 0.01) and lower TIBC (59.09 versus 68.15 μmol/l; p < 0.001) than in the control group. Logistic regression revealed that RDW, TIBC (both p < 0.001), and hepcidin (p < 0.05) significantly differentiated both groups. In T1DM children, BMI SDS negatively correlated with vitamin B12 (p < 0.01) concentration and mean corpuscular hemoglobin concentration (p < 0.05) and positively with TIBC (p < 0.01) and HbA1c (p < 0.001).

CONCLUSIONS

Patients and controls differed especially in terms of RDW and TIBC. In studied T1DM children, BMI SDS was associated to iron metabolism parameters and vitamin B12 concentration.

Erythropoietin in the general population: reference ranges and clinical, biochemical and genetic correlates

Background

Although erythropoietin has been used for decades in the treatment of anemia, data regarding endogenous levels in the general population are scarce. Therefore, we determined erythropoietin reference ranges and its clinical, biochemical and genetic associations in the general population.

Methods

We used data from 6,777 subjects enrolled in the Prevention of REnal and Vascular ENd-stage Disease (PREVEND) study. Fasting venous blood samples were obtained in the morning from all participants from 2001–2003. Serum erythropoietin concentrations were measured using a fully automated chemiluminescent enzyme-labeled immunometric assay. A genome-wide association study was performed to identify genetic determinants.

Results

Mean age (± SD) was 53 ± 12 years and 50% were female. Median (IQR) erythropoietin concentrations were 7.6 (5.8–9.9) IU/L in men and 7.9 (6.0–10.6) IU/L in women. A strong positive correlation was found between erythropoietin and waist circumference, glucose and systolic blood pressure (all P < 0.05). In subjects with normal renal function there was a strong exponential relation between hemoglobin and erythropoietin, whereas in renal impairment (eGFR < 60 mL/min/1.73m^²) this relation was linear (men) or absent (women) (P < 0.001 for interaction). Single-nucleotide polymorphisms at the HBS1L-MYB locus were shown to be related to erythropoietin levels (P < 9x10^-21), more significantly than other erythrocyte parameters.

Conclusion

We provide age-specific reference ranges for endogenous serum erythropoietin. Erythropoietin levels are positively associated with the components of the metabolic syndrome, except cholesterol. We show that even mild renal failure blunts erythropoietin production and propose the HBS1L-MYB locus as a regulator of erythropoietin.

Validation of a differential diagnostic model of diabetic nephropathy and non-diabetic renal diseases and the establishment of a new diagnostic model

BACKGROUND

The aims of the present study were to validate the differential diagnostic model of diabetic nephropathy (DN) and non-diabetic renal diseases (NDRD) established in 2003 and to establish a new diagnostic model suitable for the current clinical characteristics of DN.

METHODS

We examined 200 patients with Type 2 diabetes who underwent kidney biopsy from 2004 to 2012. The 2003 differential diagnostic model based on the data collected from 1993 to 2003 was evaluated by the diagnostic test and changes in the clinical differentiation parameters of DN and NDRD were analyzed. Logistic regression, receiver operating characteristics (ROC) curve, net reclassification improvement (NRI), and integrated discrimination improvement (IDI) analysis were applied.

RESULTS

The 2003 diagnostic model showed an accuracy of 77.5%. A significantly elevated incidence of hematuria, longer history of diabetes, and reduced level of glycated hemoglobin (HbA1c) were observed in the DN group from 2004 to 2012 compared with DN group from 1993 to 2003. Histories of diabetes mellitus (Dm), systolic blood pressure (Bp), HbA1c (Gh), hematuria (Hu), diabetic retinopathy (Dr), and hemoglobin (Hb) are independently related to DN. Thus, a new diagnostic model was constructed as follows: PDN  = exp (0.846 + 0.022 Dm + 0.033Bp + 2.050 Gh-2.664 Hu-0.078 Hb + 2.942Dr)/[1 + exp (0.846 + 0.022 Dm + 0.033 Bp + 2.050 Gh-2.664 Hu-0.078 Hb + 2.942 Dr)].Validation tests determined that the accuracy of the new model were 90.9%.

CONCLUSIONS

Changes in people with DN, clinical characteristics have reduced the diagnostic efficacy of the 2003 diagnostic model. The newly established model can provide a better, more current differentiation between DN and NDRD.

Effect of insulin and an erythropoietin-derived peptide (ARA290) on established neuritic dystrophy and neuronopathy in Akita (Ins2 Akita) diabetic mouse sympathetic ganglia

The Akita mouse is a robust model of diabetic autonomic neuropathy which develops severe diabetes following beta cell death, which occurs reproducibly at 3-4 weeks of age, and maintains the diabetic state without therapy for as long as 11 additional months. Neuritic dystrophy and neuronopathy involving prevertebral sympathetic superior mesenteric and celiac ganglia begin to develop within the first two months of onset of diabetes and are progressive with time. We have examined the effect of insulin implants resulting in normoglycemia and injections of ARA290, a small erythropoietin peptide which has no effect on glycemic parameters, on the reversal of established neuritic dystrophy and neuronopathy. We have found that 4 weeks of insulin therapy beginning at 2 months of diabetes resulted in normalization of blood glucose, body weight and HbA1c. Insulin therapy successfully reversed established neuritic dystrophy and neuronopathy to control levels. Numbers of sympathetic neurons were not significantly changed in either 3 month diabetic or insulin-treated Akita mice. Treatment with ARA290 for 7 weeks beginning at 4 months of diabetes did not result in altered metabolic severity of diabetes as measured by blood glucose, body weight or HbA1c levels. ARA290 treatment was able to decrease neuritic dystrophy by 55-74% compared to untreated diabetics or in comparison to a separate group of diabetic animals representing the 4 month treatment onset point. Surprisingly, there was no effect of ARA290 on ganglionic neuron number or ongoing neuronopathy (pale/degenerating neurons) in diabetic Akita mice during this time period. The development of neuroprotective EPO-like peptides may provide a possible future therapy for this debilitating complication of diabetes; however, it appears that discrete elements may be differentially targeted by the diabetic state and may require selective therapy.

Ethnic differences in anemia among patients with diabetes mellitus: the Diabetes Study of Northern California (DISTANCE)

To examine ethnic differences in hemoglobin testing practices and to test the hypothesis that ethnicity is an independent predictor of anemia among patients with diabetes mellitus. We conducted a panel study to assess the rate of hemoglobin testing during 1999-2001 and the period prevalence and incidence of anemia among 79,985 adults with diabetes mellitus receiving care within Kaiser Permanente of Northern California. Anemia was defined as hemoglobin <13.0 g/dL in men or < 12.0 g/dL in women. Overall, 82.1% of the cohort was tested for anemia at least once during the 3-year study period. Mixed ethnicity patients were most likely to be tested, followed by whites, blacks, Latinos, and Asians (P < 0.0001). Fifteen percent of the cohort had prevalent anemia at baseline, and an additional 22% of those tested developed anemia during the study period. Anemia was more prevalent among blacks and mixed ethnicity persons compared with other racial/ethnic groups. Anemia was also more prevalent among those >/=70 years of age or with estimated glomerular filtration rate <60 ml/min/1.73 m(2). In multivariable models, blacks had higher and Asians had lower odds of prevalent anemia and hazard ratios of incident anemia compared with whites. Within a large, diverse cohort with diabetes, ethnicity was predictive of anemia, even after adjustment for age, level of kidney function, and other potential confounders. Blacks with diabetes are at increased risk of anemia relative to whites. These differences may account for some of the observed ethnic disparities in diabetes complications.

Erythropoetin receptor expression in the human diabetic retina

Background

Recent evidence suggests erythropoietin (EPO) and the erythropoietin receptor (EPOR) may play a direct role in the pathogenesis of diabetic retinopathy. Better characterization of the EPO-EPOR signaling system in the ischemic retina may offer a new therapeutic modality for ischemic ophthalmic diseases. This study was performed to identify EPOR mRNA expression in the human diabetic eye.

Findings

EPOR antisense RNA probes were validated on human pancreas tissue. In the normal eye, EPOR was expressed in the retinal ganglion cell layer. Minimal expression was observed in the inner and outer nuclear layer. Under conditions of diabetic retinopathy, EPOR expression shifted to photoreceptor cells. Increased expression was also observed in the peripheral retina.

Conclusion

EPOR expression may be a biomarker or contribute to disease mechanisms in diabetic retinopathy.

Erythropoietic stress and anemia in diabetes mellitus

Anemia is one of the world's most common preventable conditions, yet it is often overlooked, especially in people with diabetes mellitus. Diabetes-related chronic hyperglycemia can lead to a hypoxic environment in the renal interstitium, which results in impaired production of erythropoietin by the peritubular fibroblasts and subsequent anemia. Anemia in patients with diabetes mellitus might contribute to the pathogenesis and progression of cardiovascular disease and aggravate diabetic nephropathy and retinopathy. Anemia occurs earlier in patients with diabetic renal disease than in nondiabetic individuals with chronic kidney disease. Although erythropoietin has been used to treat renal anemia for nearly two decades, debate persists over the optimal target hemoglobin level. Most guidelines recommend that hemoglobin levels be maintained between 105g/l and 125g/l. The suggested role of anemia correction--to prevent the progression of left ventricular hypertrophy in patients with diabetes mellitus--is yet to be established. However, an emphasis on regular screening for anemia, alongside that for other diabetes-related complications, might help to delay the progression of vascular complications in these patients.

Erythropoietin and its carbamylated derivative prevent the development of experimental diabetic autonomic neuropathy in STZ-induced diabetic NOD-SCID mice

Autonomic neuropathy is a significant diabetic complication resulting in increased morbidity and mortality. Studies of autopsied diabetic patients and several rodent models demonstrate that the neuropathologic hallmark of diabetic sympathetic autonomic neuropathy in prevertebral ganglia is the occurrence of synaptic pathology resulting in distinctive dystrophic neurites ("neuritic dystrophy"). Our prior studies show that neuritic dystrophy is reversed by exogenous IGF-I administration without altering the metabolic severity of diabetes, i.e. functioning as a neurotrophic substance. The description of erythropoietin (EPO) synergy with IGF-I function and the recent discovery of EPO's multifaceted neuroprotective role suggested it might substitute for IGF-I in treatment of diabetic autonomic neuropathy. Our current studies demonstrate EPO receptor (EPO-R) mRNA in a cDNA set prepared from NGF-maintained rat sympathetic neuron cultures which decreased with NGF deprivation, a result which demonstrates clearly that sympathetic neurons express EPO-R, a result confirmed by immunohistochemistry. Treatment of STZ-diabetic NOD-SCID mice have demonstrated a dramatic preventative effect of EPO and carbamylated EPO (CEPO, which is neuroprotective but not hematopoietic) on the development of neuritic dystrophy. Neither EPO nor CEPO had a demonstrable effect on the metabolic severity of diabetes. Our results coupled with reported salutary effects of EPO on postural hypotension in a few clinical studies of EPO-treated anemic diabetic and non-diabetic patients may reflect a primary neurotrophic effect of EPO on the sympathetic autonomic nervous system, rather than a primary hematopoietic effect. These findings may represent a major clinical advance since EPO has been widely and safely used in anemic patients due to a variety of clinical conditions.

Coefficient of variation of R-R intervals in electrocardiogram is a sensitive marker of anemia induced by autonomic neuropathy in type 1 diabetes

The present study investigated the relationship between hemoglobin (Hb) levels and autonomic failure using a sensitive marker, coefficient of variation of R-R intervals in electrocardiogram (CVR-R) in order to clarify a cause of normocytic normochromic anemia in type 1 diabetic patients without overt nephropathy. We recruited 46 patients with type 1 diabetes and measured creatinine clearance (Ccr), HbA1c, albuminuria, Hb levels and CVR-R of all patients. In addition, the status of diabetic retinopathy and neuropathy were also evaluated. Serum erythropoietin (EPO), Fe, total iron binding capacity, lactate dehydrogenase, total bilirubin levels and number of reticulocytes and mean corpuscular volume were also measured to distinguish types of anemia. To survey the statistical correlation existing between Hb and body mass index (BMI), Ccr, HbA1c, albuminuria or retinopathy, multiple regression analysis was performed. Serum EPO, Fe, TIBC, LDH and TB levels and number of reticulocytes and MCV were within normal limits. Multiple regression analysis disclosed that HbA1c, nephropathy evaluated by albuminuria and Ccr, and retinopathy has no concern with Hb level. There is only significant relationship between Hb levels and CVR-R. Similar results were obtained even if we analyzed a group of male and female separately. We conclude that CVR-R has the strong relationship on anemia without overt nephropathy in type 1 diabetes, indicating that autonomic failure contributes on the progression of anemia via a poor response of EPO to anemia.

Anemia and diabetic nephropathy

Anemia has recently been recognized as a frequent complication of diabetic nephropathy, appearing earlier than in nondiabetic renal disease and amplifying the risks of cardiovascular and microvascular complications. A major cause is an inappropriate erythropoietin response to anemia, often accompanied by iron deficiency and therapy with angiotensin-converting enzyme inhibitors and angiotensin receptor blockers.

Anemia and the role of erythropoietin in diabetes

Anemia is more common in patients with diabetes than without diabetes, and the problem is magnified in patients with renal impairment. Diabetic patients with anemia may be at increased risk of adverse outcomes from diabetic retinopathy, nephropathy, neuropathy, and cardiovascular disease. The etiology of anemia in diabetes is multifactorial and includes inflammation, nutritional deficiencies, concomitant autoimmune diseases, drugs, and hormonal changes in addition to kidney disease. Anemia that is associated with erythropoietin deficiency may have prognostic significance for persons with nephropathy or heart failure. In early diabetic nephropathy, damage to the peritubular fibroblasts can occur and lead to erythropoietin deficiency and anemia prior to the loss of filtration. Correction of the anemia not only leads to less fatigue, greater exercise tolerance, and an improved quality of life but also to a reduction in mortality and hospital admissions for congestive heart failure (CHF). Data are accumulating that suggest that treatment of anemia will slow the progression of microvascular and macrovascular complications, including postural hypotension from autonomic neuropathy, retinopathy, and loss of renal function from diabetic nephropathy. Promptly diagnosing and treating anemia in patients with diabetes may result in an improved quality of life and decreased morbidity and mortality.

Anemia in the elderly—Clinical findings and impact on health

Anemia is common in older people and it becomes more so with advancing decades. Because the older population is increasing, the prevalence of anemia and consequently its impact on health and healthcare expenditure is expected to rise. Although the causes and consequences of anemia have not been fully elucidated and its etiology is occasionally elusive, clinical evidence has indicated that anemia itself is a cause of morbidity and it can complicate other health conditions. The clinical approach to anemia is evolving. In the past, anemia was mainly seen as a sign of underlying disease; today, anemia is considered to be a cause of severe deterioration of quality of life, morbidity, and decline in physical function, and a risk factor for death. A better understanding of anemia in the elderly will lead to improved treatment strategies, including the more judicious use of transfusion and appropriate use of erythropoietic agents.

Normocytic normochromic anemia due to automatic neuropathy in type 2 diabetic patients without severe nephropathy: a possible role of microangiopathy

We describe here four male patients with long-term and poorly controlled type 2 diabetes mellitus. They shared many common characteristic complications, such as severe autonomic neuropathy, proliferative retinopathy and normocytic normochromic anemia without progressive renal failure and macroangiopathy. They also showed normal levels of erythropoietin and reticulocyte, which was considered relatively low. The coefficient of variation of R-R, a useful method to estimate autonomic failure, showed markedly advanced autonomic neuropathy in all four patients. Coronary angiography did not reveal stenosis, anomaly or collateral vessels, but left ventriclography showed diffuse or partial hypokinesis. Massive proteinuria, high urinary levels of N-acetyl-beta-D-glucosamidase (NAG) and beta2-microglobulin (beta2M) were detected, though creatinine clearance (Ccr) was not so deteriorated. Treatment with recombinant erythropoietin increased their hemoglobin and hematocrit levels. These common points have a possibility to be brought about by tubulointerstitial damage and microangiopathy may be involved in it.

Inappropriately low erythropoietin response for the degree of anemia in patients with noninsulin-dependent diabetes mellitus

We investigated erythropoietin (Epo) response in a cohort of diabetic patients with various types of anemia to approach the pathogenesis of some cases of "unexplained" anemia encountered among diabetics. Serum Epo levels were determined totally in 747 evaluable subjects with normal renal and hepatic function, of whom 694 had anemia. Among anemic patients, 237 were diabetics, while among the 53 nonanemic persons, there were also 21 diabetics. Diabetic and nondiabetic subjects were uniformly balanced in relation to their demographic features and were categorized according to the etiology of their anemia. Hemoglobin (Hb) did not differ between diabetic and nondiabetic subjects in all the etiological groups and in the whole population. Diabetic patients had significantly lower serum Epo levels as compared to nondiabetics (36.5+/-61 vs 69.4+/-191 IU/ml, p<0.0001), and this was true for all etiologic groups of anemia with the exception of patients with myeloproliferative disorders and those with megaloblastic anemia. The natural logarithmic (ln)-EpoxHb component was used as an index of response to anemia and was found to be significantly decreased in almost all subgroups of diabetic patients. Serum Epo levels were also negatively correlated with the percentage of glycosylated Hb, HbA1(C) (r=-0.446), and the correlation was stronger with the ln of serum Epo (r=-0.638, p<0.001). Inappropriately low serum Epo level is a uniform feature in patients with type II diabetes mellitus and may represent a constitutive blunted response to anemia or an altered metabolic rate of Epo, probably as a result of abnormal glycosylation of the cytokine.

Anemia associated with new-onset diabetes: improvement with blood glucose control

OBJECTIVE

To evaluate the mild normochromic normocytic anemia associated with new-onset diabetes in young, otherwise healthy patients.

METHODS

We undertook a retrospective review of medical records of patients with new-onset diabetes and unexplained anemia. Anemia was defined as a hemoglobin concentration of less than 12.5 g/dL in women and less than 14 g/dL in men. Patients with obvious causes of anemia, such as renal insufficiency, infection, pancreatitis, deficiency of glucose-6-phosphate dehydrogenase, hemolysis, or acute or chronic blood loss, were excluded from the study.

RESULTS

In 16 otherwise seemingly healthy patients with new-onset diabetes, a normochromic normocytic anemia (mean corpuscular volume, 86.4 +/- 4 fL) was diagnosed at initial assessment. These 16 patients (8 men and 8 women) had a mean age of 33 +/- 10 years. At diagnosis, the mean glycated hemoglobin (HbA1c) was 15.5 +/- 3.4%, the mean hemoglobin concentration was 12.5 +/- 0.6 g/dL, and the mean hematocrit was 36.2 +/- 2%. All patients were treated with insulin. After a mean follow-up of 10.8 +/- 17 months, insulin treatment resulted in a decline in HbA1c to 7.7 +/- 1.7% (P<0.001; confidence interval [CI], 5.7 to 9.8). The hemoglobin concentration increased to 14.3 +/- 0.9 g/dL (P<0.001; CI, 1.22 to 2.38), and the hematocrit increased to 42.1 +/- 1.9% (P<0.001; CI, 3.59 to 7.04). All patients had hemoglobin AA and normal levels of hemoglobin A2. Men and women had equal improvement in hematologic variables after improvement in glycemic control.

CONCLUSION

Some patients with new-onset diabetes have a mild normochromic normocytic anemia that is not attributable to usual causes, such as infection, pancreatitis, or blood loss. Improvement in glycemic control tends to be associated with normalization of hemoglobin levels. The cause of such cases of anemia may be either direct "glucose toxicity" to erythrocyte precursors in the bone marrow or perhaps oxidative stress to mature erythrocytes.