Treatment of hyperkalemia: something old, something new.

Treatment options for hyperkalemia have not changed much since the introduction of the cation exchange resin, sodium polystyrene sulfonate (Kayexalate, Covis Pharmaceuticals, Cary, NC), over 50 years ago. Although clinicians of that era did not have ready access to hemodialysis or loop diuretics, the other tools that we use today-calcium, insulin, and bicarbonate-were well known to them. Currently recommended insulin regimens provide too little insulin to achieve blood levels with a maximal kalemic effect and too little glucose to avoid hypoglycemia. Short-acting insulins have theoretical advantages over regular insulin in patients with severe kidney disease. Although bicarbonate is no longer recommended for acute management, it may be useful in patients with metabolic acidosis or intact kidney function. Kayexalate is not effective as acute therapy, but a new randomized controlled trial suggests that it is effective when given more chronically. Gastrointestinal side effects and safety concerns about Kayexalate remain. New investigational potassium binders are likely to be approved in the coming year. Although there are some concerns about hypomagnesemia and positive calcium balance from patiromer, and sodium overload from ZS-9 (ZS Pharma, Coppell, TX), both agents have been shown to be effective and well tolerated when taken chronically. ZS-9 shows promise in the acute treatment of hyperkalemia and may make it possible to avoid or postpone the most effective therapy, emergency hemodialysis.

Referral to nephrologists for chronic kidney disease care: is non-diabetic kidney disease ignored?

BACKGROUND: Late referral to nephrologists is common and associated with increased morbidity and mortality. We aimed to analyze the prevalence rates, predictors and consequences of late referral to nephrologists by primary care physicians for chronic kidney disease (CKD) care. METHODS: A retrospective analysis of 204 patients started on dialysis for CKD in two community hospitals between March 2003 and March 2005 was conducted. Relevant clinical and laboratory data were obtained from the patient records of the nephrology clinics and dialysis units. Patients referred in CKD stage 5 (estimated glomerular filtration rate <15 ml/min) were defined as late referral and patients in CKD stage 1-4 (estimated glomerular filtration rate >15 ml/min) as early referral. RESULTS: Forty-five (22%) of the 204 patients were referred late. In the multivariate analysis, non-diabetic kidney disease (odds ratio = 2.46, p = 0.02) and Charlson comorbidity index (odds ratio = 1.17, p = 0.009) were significantly associated with late referral. The late referral group had lower hematocrit and serum calcium levels, and higher serum phosphorus and parathyroid hormone levels than the early referral group (p < or =0.05) at the time of referral. Late referral resulted in less permanent vascular access for initiation of dialysis (p = 0.03). Even though there was twice the number of deaths in the late referral group in 1 year (18 vs. 9%), this was not statistically significant (p = 0.07). CONCLUSION: Referring physicians should pay special attention to patients with non-diabetic kidney disease and patients with multiple comorbidities since delayed referral to nephrologists may result in poorer patient-related outcomes. Larger and long-term prospective studies analyzing the long-term consequences of late referral to nephrologists are needed.

The 'Pull' Technique for Removal of Peritoneal Dialysis Catheters: A Call for Re-Evaluation of Practice Standards.

♦ BACKGROUND: The most commonly used peritoneal dialysis (PD) catheters have silicon tubing with attached Dacron cuffs. The current standard of care for PD catheter removal is by complete surgical dissection, withdrawing both the tubing and the cuffs. The intention is to avoid infection of any residual part of the catheter. We retrospectively analyzed our results with the alternative 'pull' technique, by which the silicon tube is pulled out, leaving the Dacron cuffs within the abdominal wall. This technique never gained popularity due to concern that the retained cuffs would get infected. ♦ METHODS: We reviewed our experience from an 18-month period, between January 2014 and June 2015. There were 46 catheter removals in 40 patients. All the catheters were of the double-cuffed coiled Tenckhoff type (Covidien, Dublin, Ireland). ♦ RESULTS: Of the 46 catheter removals by the 'pull' technique, there was only 1 case of retained cuff infection. ♦ CONCLUSIONS: The 'pull' technique is a safe method for Tenckhoff catheter removal with low risk of infection. We strongly recommend it as the procedure of choice.

Metachronous development of nonamyloidogenic [lambda] light chain deposition disease and IgG heavy chain amyloidosis in the same patient.

We report a highly unusual case of monoclonal immunoglobulin deposition disease-associated nephrotic syndrome in which a patient developed both lambda light chain deposition disease and 6 years afterward IgG-heavy chain amyloidosis. The patient initially underwent autologous peripheral blood stem cell transplantation as treatment of the underlying plasma cell dyscrasia causing the light chain deposition disease-related nephrotic syndrome. After 6 years of clinical remission, recurrence of the nephrotic syndrome led to a renal biopsy demonstrating IgG-heavy chain amyloidosis. Interestingly, much of the characteristic nodular glomerular sclerosis seen in light chain deposition disease regressed between the time of the first biopsy and the second. Given the length of time between the development of the two diseases and the apparent success of stem cell transplantation in treating the first, we think that the patient produced two distinctly different abnormal plasma cell clones. To our knowledge, this is the first report of two different monoclonal immunoglobulin deposition diseases occurring in the same patient.

Differential effects of acute administration of 19-Nor-1,25-dihydroxy-vitamin D2 and 1,25-dihydroxy-vitamin D3 on serum calcium and phosphorus in hemodialysis patients.

BACKGROUND: Treatment of hyperparathyroidism includes the use of 1,25-dihydroxy-vitamin D3 (1,25D3) to suppress parathyroid hormone (PTH), but dosing of 1,25D3 is limited by the development of hypercalcemia and a high calcium x phosphorus (Ca x P) product because of gut absorption of calcium and phosphorus and enhanced bone resorption. The vitamin D analogue 19-nor-1,25(OH)2-vitamin D2 (19-Nor) causes less hypercalcemia and elevated Ca x P, whereas it still suppresses PTH in rats. METHODS: To determine whether 19-Nor had similar effects in humans, we performed a prospective crossover study to assess bone mobilization. Ten hemodialysis patients on a low-calcium low-phosphorus diet were administered 20 microg of 1,25D3 and 120 and 160 microg of 19-Nor, and changes in calcium, phosphorus, and intact and whole PTH levels were measured over 36 hours. RESULTS: Ca x P product increased more after 1,25D3 administration than after a six- or eightfold greater dose of 19-Nor and was significantly greater at 6, 12, and 24 hours. Ca x P product at 36 hours was 60.9 +/- 3.4 (4.91 +/- 0.27 mmol2/2) after 1,25D3 administration, 53.2 +/- 2.7 (4.29 +/- 0.22 mmol2/L2) after administration of 120 microg of 19-Nor, and 54.2 +/- 2.7 (4.37 +/- 0.22 mmol2/L2) after administration of 160 microg of 19-Nor. Suppression of intact PTH at 36 hours was similar after administration of 1,25D3 (54.1% +/- 6.0%) and 120 microg of 19-Nor (54.4% +/- 3.4%) and significantly greater after administration of 160 microg of 19-Nor (63.6% +/- 2.3%). The whole PTH assay yielded values approximately 25% to 30% lower than the intact PTH assay, and the percentage of suppression was virtually identical. CONCLUSION: Consistent with animal studies, 19-Nor provides profound PTH suppression while stimulating bone resorption and/or intestinal absorption less than 1,25D3, resulting in less elevation of serum calcium and phosphorus levels.

Diuretics and disorders of calcium homeostasis.

Diuretics commonly are administered in disorders of sodium balance. Loop diuretics inhibit the Na-K-2Cl transporter and also increase calcium excretion. They are often used in the treatment of hypercalcemia. Thiazide diuretics block the thiazide-sensitive NaCl transporter in the distal convoluted tubule, and can decrease calcium excretion. They are often used in the treatment of nephrolithiasis. Carbonic anhydrase inhibitors decrease bicarbonate absorption and the resultant metabolic acidosis can increase calcium excretion. Their use can promote nephrocalcinosis and nephrolithiasis. This review will address the use of diuretics on disorders of calcium homeostasis.

DDAVP is effective in preventing and reversing inadvertent overcorrection of hyponatremia.

BACKGROUND AND OBJECTIVES: Adherence to therapeutic guidelines for the treatment of hyponatremia becomes difficult when water diuresis emerges during therapy. The objective of this study was to assess the effectiveness and safety of desmopressin acetate as a therapeutic agent to avoid overcorrection of hyponatremia and to lower the plasma sodium concentration again after inadvertent overcorrection. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Retrospective chart review was conducted of all patients who were given desmopressin acetate during the treatment of hyponatremia during 6 yr in a 528-bed community teaching hospital. RESULTS: Six patients (group 1) were given desmopressin acetate after the 24-h limit of 12 mmol/L had already been reached or exceeded; correction was prevented from exceeding the 48-h limit of 18 mmol/L in five of the six. Fourteen patients (group 2) were given desmopressin acetate in anticipation of overcorrection after the plasma sodium concentration had increased by 1 to 12 mmol/L. In all 14 patients who were treated with desmopressin acetate as a preventive measure, correction was prevented from exceeding either the 24- or 48-h limits. After desmopressin acetate was administered, the plasma sodium concentration of 14 of the 20 patients fell by 2 to 9 mmol/L. In all six group 1 patients and in five of the group 2 patients, the plasma sodium concentration was actively lowered again by the concurrent administration of desmopressin acetate and 5% dextrose in water; no serious adverse consequences from this maneuver were observed. CONCLUSION: Desmopressin acetate is effective in preventing and reversing inadvertent overcorrection of hyponatremia.