Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0019045 (hemoglobinopathies)
 2,704 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The absence of any response to the administration of recombinant human erythropoietin (rHuEpo) is exceptional in uremic patients with anemia. Initial "nonresponders" generally respond to higher doses of the hormone. However, a small number of patients may remain unresponsive. The most common cause of limited response is mild to moderate iron deficiency, either at the start of treatment or secondary to enhanced iron utilization by newly formed erythrocytes. Another common cause of resistance is the presence of an overt or, more often, an unrecognized inflammatory state, including acute or chronic infection. Marked aluminum overload and severe hyperparathyroidism also have been shown to induce resistance in at least some patients. Other factors may contribute to the severity of anemia and hence increase rHuEpo requirements, such as acute or chronic hemolytic conditions or blood loss, folate deficiency, hemoglobinopathies, and still poorly defined uremic toxins. In patients who show a resistance to the effect of the recombinant hormone, these should be sought and eliminated, if possible.
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PMID:Modulating factors in the hematopoietic response to erythropoietin. 192 86

Anemia is a frequent complication of chronic kidney disease (CKD). Inadequate production of erythropoietin by the failing kidneys leads to decreased stimulation of the bone marrow to produce red blood cells (RBCs). Anemia of CKD develops early and worsens with progressive renal insufficiency. Although over 40% of patients with CKD are anemic, anemia in this population is under-recognized and undertreated. Of considerable importance, anemia is a risk factor for cardiovascular disease and is associated with higher rates of hospitalization and mortality. Despite the availability of erythropoiesis-stimulating proteins (ESPs) to stimulate RBC production in CKD patients, approximately three fourths of patients initiating dialysis have a hemoglobin <11 g/dL. The recognition of anemia of CKD begins with an estimation of glomerular filtration rate (GFR), which can be far lower than a normal serum creatinine might suggest, especially in the elderly and in those with poor nutrition and muscle mass. If GFR is <60 mL/min/1.73 m(2), hemoglobin should be checked. The anemia is diagnosed when the hemoglobin is <12 g/dL in a man or a postmenopausal woman, or <11 g/dL in a premenopausal woman. The cause of anemia should be investigated in these individuals; this can range from erythropoietin deficiency due to CKD, to deficiency of vitamin B(12) and/or folate, iron deficiency, blood loss, inflammation, malignancy, and aluminum intoxication. After other causes of anemia have been excluded, CKD is the most likely etiology, and it should be treated with an ESP. Currently, epoetin alfa and darbepoetin alfa are the only 2 ESPs approved for use in the United States. Extended dosing of ESP has potential advantages for the patient and may also improve resource utilization. Consequently, both agents have been tested for dosing at extended intervals. Adequate iron stores--defined as transferrin saturation >20% and ferritin >100 mg--as well as ESP administration are needed to produce an appropriate increase in hemoglobin. Poor response to treatment with ESP can be due to many factors, including presence of iron deficiency, inflammation, continued blood loss, and hemoglobinopathy.
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PMID:Practical approach to the diagnosis and treatment of anemia associated with CKD in elderly. 1709 34

Recombinant human erythropoietin (rHuEPO) has transformed the management chronic renal failure (CKD) and considerably improved the outcome of patients on regular chronic dialysis. However, a significant number of patients fail to respond to high of Erythropoiesis-stimulating agents (ESAs) and several causes of inadequate response to epoetin therapy have been identified. Some factors, such as gender, age, length of time on dialysis, type of dialysis and co-morbidities such as hemoglobinopathy, are not susceptible to clinical intervention. However, many other factors can be adjusted. Iron deficiency, whether functional or absolute, is the most common factor that limits the response to rHuEPO. Monitoring of iron parameters and a large use of iron supplementation result in an efficient epoetin response. Infection and inflammation have been shown to reduce responsiveness to ESAs by disrupting iron metabolism and increasing the release of pro-inflammatory cytokines that inhibit erythropoiesis. Increase dialysis dose is associated with improvements in anemia correction and reduced requirements for ESAs. Severe hyperparathyroidism and aluminum overload lead to a reduced number of responsive erythroid progenitor cells. Finally, a number of nutritional factors, such as deficiencies of carnitine, vitamin B12, folic acid, and vitamin C, are susceptible to alter erythropoiesis. Optimizing patient response to ESAs therefore requires consideration of many of well-established factors and is important for both patient outcomes and cost of treatment.
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PMID:[Factors affecting the response to erythropoiesis-stimulating agents]. 1737 70