Recent advances in pathophysiology and treatment of hypercalcemia of malignancy

Seizures in Dialysis Patients Treated with Recombinant Erythropoietin. Review of the Literature and Guidelines for Prevention

Anemia is one of the major limitations to rehabilitation in patients with end-stage renal disease (ESRD). The efficacy of recombinant human erythropoietin (rHuEPO) in the treatment of renal anemia is well established. Nevertheless, rHuEPO therapy has been associated with serious untoward effects. There appears to be an increased risk of hypertension, not infrequently accompanied by hypertensive encephalopathy and seizures. The mechanism of hypertension remains uncertain. It is associated with an increase in blood viscosity, a reversal of hypoxic vasodilatation, and, possibly, a direct pressor effect of the hormone. Seizures, otherwise, may be the result of cerebral hypoperfusion and, finally, of a focal cerebral edema. The guidelines for rHuEPO treatment and prevention of associated convulsions are outlined. The possible convulsive risk induced by this treatment, even at low doses, particularly in patients with a previous history of seizures, is stressed.

Oral and dental aspects of chronic renal failure

The present article reviews, in detail, the current knowledge of the oral and dental aspects of chronic renal failure (CRF). Worldwide, increasing numbers of persons have CRF; thus, oral health care staffs are increasingly likely to provide care for patients with such disease. Chronic renal failure can give rise to a wide spectrum of oral manifestations, affecting the hard or soft tissues of the mouth. The majority of affected individuals have disease that does not complicate oral health care; nevertheless, the dental management of such individuals does require that the clinician understand the multiple systems that can be affected. The clinician should also consider the adverse side-effects of drug therapy and appropriate prescribing, in view of compromised renal clearance.

Calcium-free hemodialysis for hypercalcemia of malignancy in a newborn

Hypercalcemia associated with malignancy is very rare in the newborn period. Severe hypercalcemia causes neurological and cardiological disturbances and can be life threatening. Calcium-free hemodialysis has not been reported for the treatment of malignancy associated hypercalcemia in neonates. We report a 5-day-old infant with severe hypercalcemia (serum calcium 22 mg/dl) secondary to a solid tumor in the pelvis. Aggressive pharmacological treatment with furosemide, pamidronate, and calcitonin failed to reduce the serum calcium adequately. Implementation of calcium-free hemodialysis resulted in a rapid reduction of the serum calcium from 22.6 mg/dl to 11.6 mg/dl. Hemodialysis was well tolerated with no hemodynamic complications. Continuous veno-venous hemodialysis was used to maintain normocalcemia.

Normal Erythropoietin Response in Chronic Hepatitis C Patients with Ribavirin-Induced Anaemia

Background

Ribavirin administration for chronic hepatitis C is associated with the development of haemolytic anaemia, which affects treatment efficacy and tolerability. In a pilot study, the exogenous administration of erythropoietin has been shown to be beneficial, reducing the rate of ribavirin dose reduction. How ribavirin administration affects normal erythropoietin production has not been determined.

Aim

To investigate the endogenous erythropoietin response in hepatitis C patients with ribavirin-induced anaemia.

Methods

Serum erythropoietin was measured before and during interferon–ribavirin treatment in 18 HCV-positive subjects. Mathematical analysis and modelling were applied to compare the degree of erythropoietin increase in HCV-positive and in otherwise healthy anaemic patients, and estimate the endogenous excess erythropoietin production in response to ribavirin-induced anaemia.

Results

Erythropoietin concentration increased significantly in response to anaemia caused by ribavirin. The physiological erythropoietin response to the ribavirin-induced anaemia was as adequate in HCV-positive subjects as it is in anaemic subjects without liver disease. The recommended exogenous erythropoietin dose appears three-times greater than the endogenous erythropoietin boost.

Conclusion

Chronic liver damage by HCV does not affect the physiological erythropoietin response to ribavirin-induced anaemia. While the rationale for erythropoietin treatment of ribavirin-induced anaemia is not straightforward, the currently recommended dosing regimen should be reassessed.

Pharmacokinetics of recombinant human erythropoietin in children with chronic renal failure

Basal erythropoietin (Epo) levels and single dose-pharmacokinetics of recombinant human erythropoietin (rhuEpo) were investigated in 8 predialysis (PD) patients (mean age 11.6 +/- 1.4 years) and in 8 patients on continuous ambulatory peritoneal dialysis (CAPD) (mean age 12.7 +/- 0.6 years). Basal Epo levels were found to be 1.0 +/- 0.0 mu/ml in PD group, 1.6 +/- 0.7 mu/ml in CAPD group and 8.5 +/- 1.8 mu/ml in control group. Following administration of 50 mu/kg rhuEpo (s.c.) serum Epo concentration (Cmax) was 23.2 +/- 2.5 mu/ml in 18.5 +/- 2.6 hours (tmax) in PD patients and 9.9 +/- 0.8 mu/ml in 26.8 +/- 7.7 hours in CAPD patients. Mean elimination half-lives (t1/2) were 13.3 +/- 1.9 hours and 13.5 +/- 3.0 hours in PD patients and CAPD patients, respectively. The volume of distribution (Vd) was 840.0 +/- 100.0 ml/kg; the clearance (Epo Cl) was 37.0 +/- 5.5 ml/kg/hour in PD patients. These values were significantly lower in PD patients than in CAPD patients (p < 0.05) (Vd; 1500 +/- 240.0 ml/kg; Epo Cl 110 +/- 30.0 ml/kg/hour). During the course of CAPD, more efficient clearance of uraemic toxins that inhibit erythropoiesis and more rapid extraction of erythropoietin by erythroid precursors may cause higher Vd in CAPD patients than in PD patients.

Recombinant erythropoietin for the treatment of anemia in inflammatory bowel disease

BACKGROUND

Some patients with inflammatory bowel disease have anemia that is refractory to treatment with iron and vitamins. We examined whether administering iron and recombinant erythropoietin could raise hemoglobin levels in such patients.

METHODS

Thirty-four patients with inflammatory bowel disease (15 with ulcerative colitis and 19 with Crohn's disease) and anemia refractory to iron therapy (hemoglobin concentrations below 10.0 g per deciliter [6.2 mmol per liter]) were randomly assigned in a prospective, double-blind, 12-week trial to receive either oral iron (100 mg per day) and subcutaneous erythropoietin (150 U per kilogram of body weight twice per week) (n=17) or oral iron and placebo (n=17). The primary measure of efficacy was an increase in hemoglobin levels of more than 1.0 g per deciliter (0.62 mmol per liter). Additional analyses were performed with other patients with inflammatory bowel disease.

RESULTS

The severity of anemia was related to clinical disease activity as well as to in vitro monocyte secretion of interleukin-1 beta, a proinflammatory cytokine. Serum erythropoietin concentrations were increased in 52 randomly selected outpatients with inflammatory bowel disease and anemia, but the concentrations were inadequate in relation to the degree of anemia. Twelve weeks of therapy with recombinant erythropoietin and oral iron increased mean (+/-SE) hemoglobin concentrations from 8.81+/-0.27 g per deciliter (5.47+/-0.17 micromol per liter) to 10.52+/-0.41 g per deciliter (6.5+/-0.25 micromol per liter), whereas hemoglobin concentrations in the placebo group decreased from 8.69+/-0.11 g per deciliter (5.4+/-0.068 micromol per liter) to 7.84+/- 0.33 g per deciliter (4.9+/-0.2 mmol per liter) (P<0.001). After 12 weeks, hemoglobin levels had increased by more than 1.0 g per deciliter in 82 percent of the patients in the erythropoietin group, as compared with 24 percent of those in the placebo group (P=0.002). There were five treatment failures in the placebo group and two in the erythropoietin group (P=0.18); treatment failure was defined as a decrease in hemoglobin levels of more than 2.0 g per deciliter (1.24 micromol per liter) to a value below 8.0 g per deciliter (4.96 micromol per liter) or any decrease to less than 6.5 g per deciliter (4.03 micromol per liter).

CONCLUSIONS

In patients with inflammatory bowel disease and anemia refractory to treatment with iron and vitamins, treatment with oral iron and recombinant erythropoietin can raise hemoglobin levels.

Calcium free hemodialysis: experience in the treatment of 33 patients with severe hypercalcemia

OBJECTIVE

To assess the efficacy, adverse effects and relevance of calcium-free hemodialysis (CFHD) in the treatment of major hypercalcemia.

DESIGN

Retrospective chart review.

SETTING

Medical ICU.

PATIENTS

All patients admitted over a 9-year period for hypercalcemia requiring urgent treatment and who underwent hemodialysis.

INTERVENTIONS

CFHD with an acetate dialysate.

MAIN RESULTS

Thirty-three patients with severe hypercalcemia from various etiologies received CFHD. Marked and rapid decrease of serum total calcium was obtained during all sessions (mean decrease: 1.71 +/- 0.54 mmol/l). Calcium rebound within 24 h after CFHD was observed in all evaluable cases (1 +/- 0.45 mmol/l; mean delay 13.7 +/- 5.8 h). Adverse cardiovascular effects occurred in 17 of 48 sessions (35%) and in 13 of 30 evaluable patients (43%).

CONCLUSIONS

Adverse effects are frequent during CFHD. After correction of hypovolemia, its use should be restricted to patients with severe clinical symptoms or advanced renal impairment.

Hypercalcemia complicating childhood malignancies

BACKGROUND

Hypercalcemia complicating malignancy is a frequent complication in adults, but little has been published about the pathogenesis or the true incidence of hypercalcemia in children with cancer.

METHODS

Hypercalcemia developing in childhood malignancies was studied retrospectively at St. Jude Children's Research Hospital to determine its incidence, the timing of its presentation, and its response to therapy.

RESULTS

Over a 29-year period, 25 children (median age, 9.5 years) had been diagnosed and treated for hypercalcemia that occurred during the course of their malignancy. These 25 represented 0.4% of the total number of children treated for cancer at the institution during that period. Their malignancies comprised acute leukemias (11; 0.6%), rhabdomyosarcoma (4; 1.2%), malignant rhabdoid tumor (2), Hodgkin disease (1), non-Hodgkin lymphoma (1), hepatoblastoma (2), neuroblastoma (1), brain tumor (1), angiosarcoma (1), and a solid malignant tumor of undetermined type.

CONCLUSIONS

Patients with acute lymphoblastic leukemia were more likely to present with hypercalcemia at the time of their initial diagnosis and to achieve resolution of this complication, whereas patients with solid tumors presented with hypercalcemia later in the course of their disease and had hypercalcemia that was more resistant to therapy. In contrast to adults with cancer, hypercalcemia of malignancy is extremely rare in children.

Modulation of tumour-induced bone resorption by bisphosphonates

Tumour cells produce systemic or local factors which can stimulate osteoclast development and activity leading to increased bone resorption. The clinical consequences are bone pain, fractures and hypercalcaemia. Inhibitors of osteoclast-mediated bone resorption, such as the bisphosphonates, are now the treatment of choice for tumour-induced hypercalcaemia. Recent evidence indicates that these compounds, especially the newer ones, reduce skeletal morbidity in patients with metastatic bone disease and improve their quality of life. Better understanding of the mechanisms underlying tumour-induced bone resorption and development of more potent and less toxic bisphosphonates will lead to improved management of patients with malignant diseases involving the skeleton.

Recombinant human erythropoietin therapy in pediatric patients receiving long-term peritoneal dialysis

We evaluated the impact of (s.c.) recombinant human erythropoietin (r-HuEPO) therapy on the hematological status, exercise capacity, and dietary intake of nine pediatric patients (mean age 12.4 +/- 3.2 years) receiving long-term peritoneal dialysis. Five children without medical illness served as controls for the exercise testing portion of the study. Following 7.9 +/- 2.8 weeks of twice weekly r-HuEPO (50 units/kg per dose), the hematocrit increased from 21.9 +/- 3.5% to 31.3 +/- 2.5% (P less than 0.001). A further increase to 33.2 +/- 3.0% occurred after 2 months of once weekly therapy. The blood transfusion requirement decreased from 0.5 transfusions per patient-month to 0.05 transfusions per patient-month (P less than 0.01). Graded exercise testing demonstrated an increase in peak oxygen consumption from 17.8 +/- 5.2 to 24.0 +/- 7.6 ml/kg per min (P less than 0.01). The oxygen consumption at anaerobic threshold increased from 13.1 +/- 3.9 to 17.1 +/- 3.5 ml/kg per min (P less than 0.02). Treadmill time increased from 5.3 +/- 1.2 to 7.5 +/- 1.3 min (P less than 0.001). In each case, the percentage improvement was significantly greater than the improvement seen in the control population. Dietary evaluation revealed no significant change in caloric or protein intake, despite a subjectively improved appetite. r-HuEPO, given by the s.c. route, corrects the anemia and improves the exercise capacity of pediatric patients receiving long-term peritoneal dialysis.

Regulation of the production of plasminogen activators by bone resorption enhancing and inhibiting factors in three types of osteoblast-like cells

Production of proteolytic enzymes by osteoblasts is considered to be important for the initiation of osteoclastic bone resorption. We examined the production of tissue-type (tPA) and urokinase-type plasminogen activator (uPA) activity by three types of osteoblast-like cells (normal rat osteoblasts, rat and human osteosarcoma cells) using a quantitative spectrophotometric assay and a qualitative gel overlay technique. All 3 types of cells released both types of PA-activity into the medium, but normal rat osteoblasts released uPA probably in an inactive form. Treatment with different concentrations of the bone resorbing factors bovine Parathyroid Hormone [1-84], synthetic human Parathyroid Hormone-Like Protein [1-34]. Prostaglandin E2, Interleukin-1 beta, Tumor Necrosis Factor alpha and 1,25-dihydroxyvitamin D3 increased in general the production of both PA's by all three cell types. However, there were differences in the relative potencies of these factors. In contrast, Transforming Growth Factor beta, which inhibits bone resorption, decreased PA-activity in osteoblast-like cells. In all three types of cells, under control as well as under stimulated conditions, a high molecular weight form of PA was demonstrated by the gel overlay technique, most likely a complex of tPA with the PA-inhibitor PAI-1. The uniform increase in production of PA's by osteoblast-like cells in response to bone resorbing factors and its decrease by TGF beta supports the notion that PA's are involved in bone resorption. The exact mechanism however, remains to be elucidated.

Low-dose subcutaneous erythropoietin in continuous ambulatory peritoneal dialysis

We evaluated changes in hematocrit in patients on continuous ambulatory peritoneal dialysis (CAPD) before and after the administration of erythropoietin (EPO). Thirty-five patients were evaluated at the beginning of treatment with CAPD and after an average of 3.5 years on CAPD; mean hematocrit (Hct) rose from 25.4 +/- 5.4% to 28.1 +/- 6.7% (P less than 0.001). In the period before EPO administration 11 patients required a total of 44 transfusions (one patient needed 23 transfusions). Fifteen patients were started on subcutaneous erythropoietin 3,000 units 3 times a week and were followed for a mean period of 6.3 months. Hct rose from 23.8 +/- 1.8% to 25.2 +/- 2.4% (P less than 0.01) within the first 2 weeks and up to 27.5 +/- 3.7% (P less than 0.01) in the fourth week. By the eighth week the target Hct (30 to 35%) was reached. During the next 5 months the EPO doses were adjusted to each patient's needs ranging between 2,000 U per week to 4,000 U 3 times per week. Mild hypertension was the only side effect seen in some of the patients. In conclusion low dose subcutaneous EPO is effective in managing the anemia of patients on CAPD with only minor side effects.