Extrarenal effect of cyclosporine A on potassium homeostasis in renal transplant recipients

Mechanisms and management of drug-induced hyperkalemia in kidney transplant patients

Hyperkalemia is a common and potentially life-threatening complication following kidney transplantation that can be caused by a composite of factors such as medications, delayed graft function, and possibly potassium intake. Managing hyperkalemia after kidney transplantation is associated with increased morbidity and healthcare costs, and can be a cause of multiple hospital admissions and barriers to patient discharge. Medications used routinely after kidney transplantation are considered the most frequent culprit for post-transplant hyperkalemia in recipients with a well-functioning graft. These include calcineurin inhibitors (CNIs), pneumocystis pneumonia (PCP) prophylactic agents, and antihypertensives (angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, beta blockers). CNIs can cause hyperkalemic renal tubular acidosis. When hyperkalemia develops following transplantation, the potential offending medication may be discontinued, switched to another agent, or dose-reduced. Belatacept and mTOR inhibitors offer an alternative to calcineurin inhibitors in the event of hyperkalemia, however should be prescribed in the appropriate patient. While trimethoprim/sulfamethoxazole (TMP/SMX) remains the gold standard for prevention of PCP, alternative agents (e.g. dapsone, atovaquone) have been studied and can be recommend in place of TMP/SMX. Antihypertensives that act on the Renin-Angiotensin-Aldosterone System are generally avoided early after transplant but may be indicated later in the transplant course for patients with comorbidities. In cases of mild to moderate hyperkalemia, medical management can be used to normalize serum potassium levels and allow the transplant team additional time to evaluate the function of the graft. In the immediate post-operative setting following kidney transplantation, a rapidly rising potassium refractory to medical therapy can be an indication for dialysis. Patiromer and sodium zirconium cyclosilicate (ZS-9) may play an important role in the management of chronic hyperkalemia in kidney transplant patients, although additional long-term studies are necessary to confirm these effects.

Interaction of cyclosporin A molecules with alkali and transition metal atoms on Cu(111)

The structure of a cyclic peptide with important biological functionalities, cyclosporin A (CsA), is investigated at the single molecule level. Its adsorption on Cu(111) under ultra-high vacuum is characterised with scanning tunnelling microscopy (STM) and density functional theory. With STM investigations, we demonstrate element specific on-surface coordination schemes of CsA with coadsorbed K, Co and Fe atoms. Thus, clear insights emerge in the behaviour of cyclic peptides at interfaces and their interactions with different metal atoms, providing control of the adsorption structure and assembly and paving the way for the integration of cyclic peptides in functional metal-organic nanostructures on surfaces.

Plasma levels of norepinephrine and expression levels of ß2-adrenergic receptor gene correlate with the incidence of acute graft-versus-host disease

Background: Acute graft-versus-host disease is a major complication in allogeneic hematopoietic stem-cell transplantation. Epinephrine and norepinephrine are stress hormones which affect many cells, including immune cells through interaction with adrenergic receptors, mainly β2-adrenergic receptor. The immunomodulatory effects of epinephrine, norepinephrine, and signaling of the adrenergic receptor have been shown to decrease the probability of the acute graft-versus-host disease in animal models. The aim of our study was to investigate the possible correlations between the serum levels of epinephrine and norepinephrine and also leukocytic expression levels of β2-adrenergic receptor with the incidence of acute graft-versus-host disease in patients undergoing allogeneic hematopoietic stem-cell transplantation. Methods: In this study, the plasma levels of epinephrine and norepinephrine and the leukocytic expression of β2-adrenergic receptor gene were measured and compared in allogeneic hematopoietic stem-cell transplantation patients with and without acute graft-versus-host disease. Data were analyzed and illustrated using SPSS 19 and GraphPad Prism 6. The student T-test, Pearson, and Spearman's tests were performed and p<0.05 was considered as significant. Results: We showed that the plasma levels of norepinephrine and the relative amount of the mRNA of β2-adrenergic receptor at 7 and 21 days after allogeneic hematopoietic stem-cell transplantation were significantly lower in patients with acute graft-versus-host disease than recipients without acute graft-versus-host disease. There were also negative correlations between the plasma levels of norepinephrine, leukocytic levels of the mRNA of β2-adrenergic receptor, and the incidence of acute graft-versus-host disease. Conclusion: Our results suggest that stress hormones and their receptor might have a role in preventing acute graft-versus-host disease and could be promising factors in controlling the outcome of allogeneic hematopoietic stem-cell transplantation.

Electrolyte and Acid-base disturbances induced by clacineurin inhibitors

Nephrotoxicity is the most common and clinically significant adverse effect of calcineurin inhibitors. Cyclosporine and tacrolimus nephrotoxicity is manifested by both acute azotemia and chronic progressive renal disease and tubular zdysfunction. An elevation in the plasma potassium concentration due to reduced efficiency of urinary potassium excretion is common in cyclosporine-treated patients; it may be severe and potentially life-threatening with concurrent administration of an angiotensin converting enzyme inhibitor, which diminishes aldosterone release. Tubular injury induced by cyclosporine can also impair acid excretion. This may be presented as a hyperchloremic metabolic acidosis associated with decreased aldosterone activity and suppression of ammonium excretion by hyperkalemia. Some patients treated with cyclosporine develop hypophosphatemia due to urinary phosphate wasting. Renal magnesium wasting is also common presumably due to drug effects on magnesium reabsorption. Hypomagnesemia has also been implicated as a contributor to the nephrotoxicity associated with cyclosporine. Both cyclosporine and tacrolimus are associated with hypercalciuria. Attention must be paid to drug dose, side effects, and drug interactions to minimize toxicity and maximize efficacy.

Severe hyperkalemic type 4 renal tubular acidosis after kidney transplantation: a case report

BACKGROUND

Hyperkalemia after transplantation is a common event, occurring in up to 70% of patients. It is usually asymptomatic but sometimes manifests as muscle weakness or cardiac arrhythmias.

METHODS

Case report.

RESULTS

At 102 days after a second cadaveric kidney transplantation, a 15-year-old boy, was admitted to the emergency room with severe muscle weakness. His examinations showed a serum potassium of 9.8 mEq/L; blood pH 7.1; serum bicarbonate 7.6 mmol/L; and creatinine 2.5 mg/dL. He was initially treated with sodium bicarbonate, calcium gluconate, and furosemide. Subsequent investigation showed hyperchloremic metabolic acidosis, urinary pH <5.5, positive urinary anion gap, reduced transtubular potassium gradient (TTKG, 1.5) and low levels of aldosterone (0.7 ng/mL), suggesting the presence of type 4 renal tubular acidosis (RTA). Other causes of hyperkalemia were excluded in the present case. Serum levels of potassium returned to normal when fludrocortisone was added to the bicarbonate supplementation. This case of severe hyperkalemic secondary to type 4 RTA after kidney transplantation only responded to the combination of alkali and mineralocorticoid therapies.

Managing the Failing Allograft

Managing the failing allograft juxtaposes immunosuppressive management and routine chronic kidney disease care. The complications of immunosuppression can be more pronounced in those with renal failure (infection, anemia, bone disease). The withdrawal of immunosuppression may be associated with acute allograft rejection, arthralgias, and the development of antidonor antibodies. Likewise depression is prevalent. Improving well-being and overall survival necessitates proper titration of immunosuppressive medications and control of blood pressure, anemia, lipids, and glucose along with attention to treatment of depression.

Isolated hyperkalemia associated with cyclosporine administration in allogeneic stem cell transplantation for renal cell carcinoma

Two patients with advanced renal cell carcinoma underwent allogeneic hematopoietic stem cell transplantation and received cyclosporine (CSP) as part of their immunosuppressive therapy. Despite adequate renal function, both patients developed hyperkalemia. CSP was the only pharmaceutical agent to which this electrolyte abnormality could be attributed. Evaluation of renal tubule function suggested that CSP-associated isolated hyperkalemia resulted from tubular resistance to aldosterone. We propose that the presence of a single functional kidney may be a risk factor for isolated hyperkalemia due to CSP.

Cyclosporine-associated hyperkalemia: report of four allogeneic blood stem-cell transplant cases

BACKGROUND

Nephrotoxicity is a well-known effect of cyclosporine (CsA) that causes a reduction in glomerular filtration rate through vasoconstriction of the afferent glomerular arterioles and may result in acute renal failure. Isolated CsA-induced hyperkalemia occurring through different mechanisms is also common. However, there are only a few "case reports" addressing this phenomenon in allogeneic bone marrow transplantation patients. In this report, we propose mechanisms and methods of managing CsA-associated hyperkalemia in allogeneic transplantation.

METHODS

We report on four allogeneic blood stem- cell transplant cases and a review of the literature.

RESULTS

Four adult leukemia patients underwent allogeneic peripheral blood stem cell transplantation and received CsA as a part of their graft-versus-host disease prophylaxis. The patients developed hyperkalemia, despite adequate kidney function. CsA seemed to be the only pharmaceutical agent to which this electrolyte abnormality could be attributed. Renal tubule dysfunction and secondary hypoaldosteronism seemed to be the reasons for CsA-associated hyperkalemia.

CONCLUSION

This report of four cases demonstrates that CsA should be considered among the possible causes of hyperkalemia in bone marrow transplantation. There may be a need for urgent intervention depending on the severity of hyperkalemia. Monitoring of blood CsA level and dose adjustment are important for the prevention of this complication.

Drug-induced hyperkalemia: old culprits and new offenders

Prescribed medications, over-the-counter drugs, and nutritional supplements are used by many patients. Although most of these products are well tolerated, drug-induced hyperkalemia may develop in patients with underlying renal impairment or other abnormalities in potassium handling. Drug-induced hyperkalemia most often occurs from impaired renal potassium excretion. However, disturbed cellular uptake of a potassium load as well as excessive ingestion or infusion of potassium-containing substances may also occur. Physicians must be aware of medications that can precipitate hyperkalemia, how these drugs induce alterations in potassium homeostasis, and the patient characteristics that increase the risk of hyperkalemia.