Does hypokalemia contribute to acute kidney injury in chronic laxative abuse?

Association between the hypokalaemia index based on area over the serum potassium concentration curve and occurrence of acute kidney injury in patients administered liposomal amphotericin B

BACKGROUND

Acute kidney injury (AKI) and hypokalaemia are common adverse events after treatment with liposomal amphotericin B (L-AMB).

OBJECTIVES

Because excess potassium (K) leakage occurs during renal tubular injury caused by L-AMB, measuring the decrease in rate of serum K concentration might be more useful to assess the renal impact of L-AMB than hypokalaemia identified from a one-point measurement. The effects of a decrease in K concentration and duration of hypokalaemia on AKI were investigated.

METHODS

A ≥ 10% decrease in K concentration from the reference concentration within a 7-day timeframe was evaluated. The hypokalaemia index, which combines the duration of K concentration lower than the reference and a marked low K concentration, was calculated from the area over the concentration curve.

RESULTS

Eighty-six patients were included in the study. The incidences of AKI and decrease in K concentration were 36.0% and 63.9%, respectively. Of patients who developed both adverse events, a decrease in K concentration occurred first in 22 of 26 patients, followed by AKI 7 days later. Hypokalaemia did not increase AKI risk whereas a decrease in K concentration was an independent risk factor for AKI. The hypokalaemia index in patients with AKI was significantly higher than those without AKI (5.35 vs. 2.50 points, p = 0.002), and ≥3.45 points was a significant predictor for AKI.

CONCLUSION

A ≥ 10% decrease in the K concentration was a significant factor for AKI in patients receiving L-AMB therapy. In such patients, dose reduction or alternative antifungals could be considered based on the hypokalaemia index.

Improvement in Tubulointerstitial Nephritis With Glucocorticoid Therapy in an Anorexia Nervosa Patient

Anorexia nervosa is a psychiatric disorder that is often diagnosed in adolescents and young adults. Renal-related complications of anorexia nervosa include abnormal water metabolism, electrolyte abnormalities, and nephrocalcinosis, which may lead to irreversible renal damage. Furthermore, tubulointerstitial nephritis has been reported as a renal pathological feature of anorexia nervosa. Immunosuppressive therapy, such as with glucocorticoids, has been recommended for idiopathic interstitial nephritis treatment; however, the effectiveness of immunosuppressive therapy for interstitial nephritis in patients with anorexia nervosa remains unestablished. Here, we report a case of interstitial nephritis in a patient with anorexia nervosa whose renal function was successfully improved with glucocorticoid therapy. The patient was a 38-year-old woman who was referred for renal dysfunction (estimated glomerular filtration rate: 7.6 mL/min/1.73 m2). She had anorexia nervosa and repeated episodes of vomiting. Hypokalemia (K: 2.1 mEq/L) and metabolic alkalosis (HCO3-: 54.2 mEq/L) were observed. Fluid therapy and potassium supplementation did not improve renal function; therefore, a percutaneous renal biopsy was performed. The renal pathology results revealed interstitial fibrosis, inflammatory cell infiltration in the interstitium, and tubulitis, suggesting a diagnosis of tubulointerstitial nephritis. Glucocorticoid therapy improved the patient's renal function to an estimated glomerular filtration rate of 19.91 mL/min/1.73 m2, and the renal function remained stable thereafter. This case suggests that glucocorticoid therapy may be considered for the treatment of interstitial nephritis in patients with anorexia.

Renal and electrolyte complications in eating disorders: a comprehensive review

Eating disorders are psychiatric disorders with significant and widespread medical complications, including renal disorders. Renal disease is not uncommon in patients with eating disorders but is often unrecognized. It includes both acute renal injury and progression to chronic kidney disease requiring dialysis. Electrolyte abnormalities including hyponatremia, hypokalemia, and metabolic alkalosis are common in eating disorders and vary depending on whether patients engage in purging behaviors. Chronic hypokalemia due to purging in patients with anorexia nervosa-binge purge subtype or bulimia nervosa can lead to hypokalemic nephropathy and chronic kidney disease. Additional electrolyte derangements are seen during refeeding, including hypophosphatemia, hypokalemia, and hypomagnesemia. Patients can also develop Pseudo-Bartter's syndrome which leads to edema and rapid weight gain in patients who cease purging behavior. Clinicians and patients should be aware of these complications in order to provide education and early detection and prevention.

Hypokalemia in patients with anorexia nervosa during refeeding is associated with binge-purge behavior, lower body mass index, and hypoalbuminemia

BACKGROUND

Hypokalemia is frequently found in patients with anorexia nervosa and sometimes leads to life-threatening conditions. Although their serum potassium levels are considered to further decrease during refeeding, no previous studies have addressed actual changes in the serum potassium levels and potential mechanisms underlying hypokalemia during the refeeding period of patients with anorexia nervosa. In this study, we investigated factors associated with hypokalemia during refeeding of patients with anorexia nervosa.

METHODS

We recruited 52 independent patients from 89 admissions with anorexia nervosa (body mass index, 13.0 ± 3.3) from the psychiatry unit in Ashikaga Red Cross Hospital during the period from April 2003 to March 2018 and analyzed serum potassium levels at admission. Of the 89 admissions, 66 admissions with > 1-week hospitalization were recruited to determine the lowest potassium levels during the refeeding period. We analyzed these levels with multiple linear regression analysis with explanatory variables, including data upon admission and treatment-related indicators.

RESULTS

The initial serum potassium level of 3.6 ± 0.9 mg/dl decreased to 3.1 ± 0.7 mg/dl at nadir hypophosphatemia, which was observed an average of 2.5 days after admission. A lower serum potassium level at admission and a lower nadir potassium level during refeeding were associated with a lower body mass index, hypoalbuminemia, and binge-purge behavior. Similar results were obtained when the analysis included restrictive or binge-purge types as well as the independent patient group.

CONCLUSIONS

Lower body mass index, hypoalbuminemia, and binge-purge behavior might be used as indicators to guide clinical approaches for controlling serum potassium levels in patients with anorexia nervosa during refeeding. Hypokalemia, low levels of serum potassium, in patients with anorexia nervosa sometimes leads to life-threatening conditions. Thus, it is of great importance to predict the risk of hypokalemia in patients with anorexia nervosa during the refeeding period. Our study found that hypokalemia in patients with anorexia nervosa during refeeding is associated with a lower body mass index and hypoalbuminemia (low levels of serum albumin), in addition to binge-purge behavior.

Laxative Use and Risk of Dyskalemia in Patients with Advanced CKD Transitioning to Dialysis

BACKGROUND

Patients with advanced CKD experience increased intestinal potassium excretion. This compensatory mechanism may be enhanced by laxative use; however, little is known about the association of laxative use with risk of dyskalemia in advanced CKD.

METHODS

Our study population encompassed 36,116 United States veterans transitioning to ESKD from 2007 to 2015 with greater than or equal to one plasma potassium measurement during the last 1-year period before ESKD transition. Using generalized estimating equations with adjustment for potential confounders, we examined the association of time-varying laxative use with risk of dyskalemia (i.e., hypokalemia [potassium <3.5 mEq/L] or hyperkalemia [>5.5 mEq/L]) versus normokalemia (3.5-5.5 mEq/L) over the 1-year pre-ESKD period. To avoid potential overestimation of dyskalemia risk, potassium measurements within 7 days following a dyskalemia event were disregarded in the analyses.

RESULTS

Over the last 1-year pre-ESKD period, there were 319,219 repeated potassium measurements in the cohort. Of these, 12,787 (4.0%) represented hypokalemia, and 15,842 (5.0%) represented hyperkalemia; the time-averaged potassium measurement was 4.5 mEq/L. After multivariable adjustment, time-varying laxative use (compared with nonuse) was significantly associated with lower risk of hyperkalemia (adjusted odds ratio [aOR], 0.79; 95% confidence interval [95% CI], 0.76 to 0.84) but was not associated with risk of hypokalemia (aOR, 1.01; 95% CI, 0.95 to 1.07). The results were robust to several sensitivity analyses.

CONCLUSIONS

Laxative use was independently associated with lower risk of hyperkalemia during the last 1-year pre-ESKD period. Our findings support a putative role of constipation in potassium disarrays and also support (with a careful consideration for the risk-benefit profiles) the therapeutic potential of laxatives in hyperkalemia management in advanced CKD.

Laxative Use and Change in Estimated Glomerular Filtration Rate in Patients With Advanced Chronic Kidney Disease

OBJECTIVES

Constipation is highly prevalent in advanced chronic kidney disease (CKD), due in part to dietary (e.g., fiber) restrictions, and is often managed by laxatives; however, the effect of laxative use on kidney function in advanced CKD remains unclear. We aimed to examine the association of laxative use with longitudinal change in estimated glomerular filtration rate (eGFR) in patients with advanced CKD.

DESIGN AND METHODS

In a retrospective cohort of 43,622 US veterans transitioning to end-stage renal disease (ESRD) from 2007 to 2015, we estimated changes in eGFR (slope) by linear mixed-effects models using ≥2 available outpatient eGFR measurements during the 2-year period before transition to ESRD. The association of laxative use with change in eGFR was examined by testing the interaction of time-varying laxative use with time for eGFR slope in the mixed-effects models with adjustment for fixed and time-varying confounders.

RESULTS

Laxatives were prescribed in 49.8% of patients during the last 2-year pre-ESRD period. In the crude model, time-varying laxative use was modestly associated with more progressive eGFR decline compared with non-use of laxatives (median [interquartile interval] -7.1 [-11.9, -4.3] vs. -6.8 [-11.6, -4.0] mL/min/1.73 m²/year, P < .001). After multivariable adjustment, a faster eGFR decline associated with laxative use (vs. non-use of laxatives) remained statistically significant, although the between-group difference in eGFR slope was minimal (median [interquartile interval] -8.8 [-12.9, -5.9] vs. -8.6 [-12.6, -5.6] mL/min/1.73 m²/year, P < .001). The significant association was no longer evident across different types of laxatives (i.e., stool softeners, stimulants, or hyperosmotics).

CONCLUSIONS

There was a clinically negligible association of laxative use with change in eGFR during the last 2-year pre-ESRD period, suggesting the renal safety profile of laxatives in advanced CKD patients.

K+ deficiency caused defects in renal tubular cell proliferation, oxidative stress response, tissue repair and tight junction integrity, but enhanced energy production, proteasome function and cellular K+ uptake

Hypokalemia is a common electrolyte disorder in hospitalized patients and those with chronic diseases and is associated with renal tubular injury. Our recent expression proteomics study revealed changes in levels of several proteins in renal tubular cells during K⁺ deficiency. However, functional significance and mechanisms underlying such changes remained unclear. The present study, thus, aimed to investigate functional changes of renal tubular cells induced by K⁺ deficiency. MDCK cells were maintained in normal-K⁺ (ANK; [K⁺] = 5.0 mM), Low-K⁺ (ALK; [K⁺] = 2.5 mM), or K⁺-depleted (AKD; [K⁺] = 0 mM) medium. Cell count and cell death assay showed that ALK and AKD groups had marked decrease in cell proliferation without significant change in cell death. Other functional investigations revealed that AKD cells had significantly increased levels of carbonylated proteins (by OxyBlot assay), impaired tissue repair (by scratch assay), defective tight junction (by Western blotting, immunofluorescence staining and measuring transepithelial electrical resistance), increased intracellular ATP level (by ATP measurement), decreased levels of ubiquitinated proteins (by Western blotting), and increased level of Na⁺/K⁺-ATPase (by Western blotting), which was consistent with the increased cellular K⁺ uptake after K⁺ repletion. Our findings have shown that AKD caused defects in cell proliferation, oxidative stress response, tissue repair and tight junction integrity, but on the other hand, enhanced energy production, proteasome function and cellular K⁺ uptake. These findings may shed light onto cellular response to K⁺ deficiency and better understanding of both pathogenic and compensatory mechanisms in hypokalemic nephropathy.

Kaliopenic nephropathy revisited

In the ‘older’ literature, a definitive renal pathology was described in patients with long-standing hypokalaemia and depletion of the body's potassium reserves. The topic is relevant because possibly a quite cheaply reversible element in the course of chronic kidney disease progression could be addressed. Earlier, pathologists drew attention to vacuolar changes in renal tubular epithelium accompanied by inflammatory interstitial changes in patients with potassium losses. The diagnostic term ‘kaliopenic nephropathy’ was coined to describe such patients. Kaliopenic nephropathy now receives less emphasis than in earlier times. However, with eating disorders, laxative abuse and other potential causes, we suggest that the syndrome should be resurrected.