Hypokalaemia-induced acute renal failure

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.

Association between potassium supplementation and the occurrence of acute kidney injury in patients with hypokalemia administered liposomal amphotericin B: a nationwide observational study

Background

Hypokalemia and acute kidney injury (AKI) occur in patients administered liposomal amphotericin B (L-AMB), a wide-spectrum anti-fungicidal drug. However, the association between potassium supplementation and the occurrence of AKI in patients with hypokalemia who were administered L-AMB is not well understood.

Methods

Using nationwide claims data and laboratory data, the occurrence of AKI during L-AMB treatment was retrospectively compared between patients with hypokalemia who were or were not supplemented with potassium and between those adequately or inadequately supplemented with potassium (serum potassium levels corrected to ≥3.5 mEq/L or remained < 3.5 mEq/L, respectively) before or after L-AMB treatment initiation.

Results

We identified 118 patients who developed hypokalemia before L-AMB treatment initiation (43 received potassium supplementation [25 adequate and 18 inadequate supplementation] and 75 did not receive potassium supplementation), and 117 patients who developed hypokalemia after L-AMB initiation (79 received potassium supplementation [including 23 adequate and 15 inadequate supplementation] and 38 did not receive potassium supplementation). The occurrence of any stage of AKI was similar between patients with hypokalemia, regardless of potassium supplementation (i.e., before L-AMB treatment initiation [supplementation, 51%; non-supplementation, 45%; P = 0.570] or after L-AMB initiation [supplementation, 28%; non-supplementation, 32%; P = 0.671]). After adjusting for confounding factors, we found that the occurrence of any stage of AKI was not associated with potassium supplementation before L-AMB initiation (odds ratio [OR]: 1.291, 95% confidence interval [CI]: 0.584–2.852, P = 0.528) or after L-AMB initiation (OR: 0.954, 95% CI: 0.400–2.275, P = 0.915). The occurrence of any stage of AKI tended to decline in patients with hypokalemia who were adequately supplemented with potassium (44%) before, but not after, L-AMB initiation relative to that in patients inadequately supplemented with potassium (61%), however this result was not significant (P = 0.358).

Conclusion

Potassium supplementation was not associated with any stage of AKI in patients with hypokalemia who were administered L-AMB.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-021-02450-7.

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.

Factor analysis of acute kidney injury in patients administered liposomal amphotericin B in a real-world clinical setting in Japan

Liposomal amphotericin B (L-AMB) is a broad-spectrum antifungal drug that is used to treat fungal infections. However, clinical evidence of its use in patients with renal failure is limited. Here, we aimed to identify factors associated with acute kidney injury (AKI) in patients administered L-AMB. We retrospectively utilized a combination of Diagnosis Procedure Combination data and laboratory data obtained from hospitals throughout Japan between April 2008 and January 2018. In total, 507 patients administered L-AMB were identified. After L-AMB treatment initiation, AKI, which was defined as a ≥ 1.5-fold increase within 7 days or ≥ 0.3 mg/dL increase within 2 days in serum creatinine according to the KDIGO criteria, was recognized in 37% of the total patients (189/507). The stages of AKI were stage 1 in 20%, stage 2 in 11%, and stage 3 in 7%. Five factors were associated with AKI of all stages: prior treatment with angiotensin-converting enzyme inhibitors/angiotensin-receptor blockers or carbapenem; concomitant administration of catecholamines or immunosuppressants; and ≥ 3.52 mg/kg/day of L-AMB dosing. Serum potassium < 3.5 mEq/L before L-AMB therapy was associated with severe AKI of stage 2 and 3. Altogether, these factors should be carefully considered to reduce the occurrence of AKI in patients administered L-AMB.

Prolonged K+ deficiency increases intracellular ATP, cell cycle arrest and cell death in renal tubular cells

BACKGROUND

Chronic potassium (K⁺) deficiency can cause renal damage namely hypokalemic nephropathy with unclear pathogenic mechanisms. In the present study, we investigated expression and functional alterations in renal tubular cells induced by prolonged K⁺ deficiency.

METHODS

MDCK cells were maintained in normal-K⁺ (CNK) (K⁺=5.3mmol/L), low-K⁺ (CLK) (K⁺=2.5mmol/L), or K⁺-depleted (CKD) (K⁺=0mmol/L) medium for 10days (n=5 independent cultures/condition). Differentially expressed proteins were identified by a proteomics approach followed by various functional assays.

RESULTS

Proteomic analysis revealed 46 proteins whose levels significantly differed among groups. The proteomic data were confirmed by Western blotting. Gene Ontology (GO) classification and protein network analysis revealed that majority of the altered proteins participated in metabolic process, whereas the rest involved in cellular component organization/biogenesis, cellular process (e.g., cell cycle, regulation of cell death), response to stress, and signal transduction. Interestingly, ATP measurement revealed that intracellular ATP production was increased in CLK and maximum in CKD. Flow cytometry showed cell cycle arrest at S-phase and G2/M-phase in CLK and CKD, respectively, consistent with cell proliferation and growth assays, which showed modest and marked degrees of delayed growth and prolonged doubling time in CLK and CKD, respectively. Cell death quantification also revealed modest and marked degrees of increased cell death in CLK and CKD, respectively.

CONCLUSIONS

In conclusion, prolonged K⁺ deficiency increased intracellular ATP, cell cycle arrest and cell death in renal tubular cells, which might be responsible for mechanisms underlying the development of hypokalemic nephropathy.

Non-uniform Progression of Chronic Tubulointerstitial Nephritis and Widespread Nephrocalcification in a Patient with Anorexia Nervosa

Although patients with anorexia nervosa (anorexia) are known to show tubulointerstitial nephritis (TIN), the pathophysiology of its progression is not fully understood. We herein report a 31-year-old woman with anorexia who showed acute exacerbation of chronic kidney disease. Renal biopsy showed non-uniform chronic TIN; some areas were obsolete lesions and other areas were active lesions. In addition, many calcium-containing crystals were widely deposited in the distal tubules. The results suggest that chronic TIN in the setting of anorexia does not uniformly progress and that not only TIN but also widespread calcification of distal tubules might aggravate the renal function of anorexia patients.

Non-obvious correlations to disease management unraveled by Bayesian artificial intelligence analyses of CMS data

OBJECTIVE

Given the availability of extensive digitized healthcare data from medical records, claims and prescription information, it is now possible to use hypothesis-free, data-driven approaches to mine medical databases for novel insight. The goal of this analysis was to demonstrate the use of artificial intelligence based methods such as Bayesian networks to open up opportunities for creation of new knowledge in management of chronic conditions.

MATERIALS AND METHODS

Hospital level Medicare claims data containing discharge numbers for most common diagnoses were analyzed in a hypothesis-free manner using Bayesian networks learning methodology.

RESULTS

While many interactions identified between discharge rates of diagnoses using this data set are supported by current medical knowledge, a novel interaction linking asthma and renal failure was discovered. This interaction is non-obvious and had not been looked at by the research and clinical communities in epidemiological or clinical data. A plausible pharmacological explanation of this link is proposed together with a verification of the risk significance by conventional statistical analysis.

CONCLUSION

Potential clinical and molecular pathways defining the relationship between commonly used asthma medications and renal disease are discussed. The study underscores the need for further epidemiological research to validate this novel hypothesis. Validation will lead to advancement in clinical treatment of asthma & bronchitis, thereby, improving patient outcomes and leading to long term cost savings. In summary, this study demonstrates that application of advanced artificial intelligence methods in healthcare has the potential to enhance the quality of care by discovering non-obvious, clinically relevant relationships and enabling timely care intervention.

Serum Potassium, Mortality, and Kidney Outcomes in the Atherosclerosis Risk in Communities Study

OBJECTIVES

To investigate the association between serum potassium, mortality, and kidney outcomes in the general population and whether potassium-altering medications modify these associations.

PATIENTS AND METHODS

We studied 15,539 adults in the Atherosclerosis Risk in Communities Study. Cox proportional hazard regression was used to investigate the association of serum potassium at baseline (1987-1989), evaluated categorically (hypokalemia, <3.5 mmol/L; normokalemia, ≥3.5 and <5.5 mmol/L; hyperkalemia, ≥5.5 mmol/L) and continuously using linear spline terms (knots at 3.5 and 5.5 mmol/L), with mortality, sudden cardiac death, incident chronic kidney disease, and end-stage renal disease. The end date of follow-up for all outcomes was December 31, 2012. We also evaluated whether classes of potassium-altering medications modified the association between serum potassium and adverse outcomes.

RESULTS

Overall, 413 (2.7%) of the participants had hypokalemia and 321 (2.1%) had hyperkalemia. In a fully adjusted model, hyperkalemia was significantly associated with mortality (hazard ratio, 1.24; 95% CI, 1.04-1.49) but not sudden cardiac death, chronic kidney disease, or end-stage renal disease. Hypokalemia as a categorical variable was not associated with any outcome; however, associations of hypokalemia with all-cause mortality and kidney outcomes were observed among those who were not taking potassium-wasting diuretics (all P for interaction, <.001).

CONCLUSIONS

Higher values of serum potassium were associated with a higher risk of mortality in the general population. Lower levels of potassium were associated with adverse kidney outcomes and mortality among participants not taking potassium-wasting diuretics.

The medical complications associated with purging

OBJECTIVE

Purging behaviors, including self-induced vomiting, laxative abuse, and diuretic abuse, are present across many of the eating disorders. Here we review the major medical complications of these behaviors.

METHOD

Although we identified over 100 scholarly articles describing medical complications associated with purging, most papers involved case studies or small, uncontrolled samples. Given the limited evidence base, we conducted a qualitative (rather than systematic) review to identify medical complications that have been attributed to purging behaviors.

RESULTS

Medical conditions affecting the teeth, esophagus, gastrointestinal system, kidneys, skin, cardiovascular system, and musculoskeletal system were identified, with self-induced vomiting causing the most medical complications.

DISCUSSION

Purging behavior can be associated with severe medical complications across all body systems. Mental health professionals should refer patients with purging behaviors to medical providers for screening and treatment as needed. The medical work-up for individuals with eating disorders should include a comprehensive metabolic panel, complete blood count, and a full body exam including the teeth to prevent severe complications. Medical providers should screen patients for purging behaviors and associated medical complications, even in the absence of an eating disorder diagnosis, to increase the detection of eating disorders. Recognizing the link between purging and medical complications can aid in identifying potential eating disorders, particularly those that often elude detection such as purging disorder.

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

Prolonged hypokalemia from chronic laxative abuse is recognized as the cause of chronic tubulointerstitial disease, known as “hypokalemic nephropathy,” but it is not clear whether it contributes to acute kidney injury (AKI). A 42-year-old woman with a history of chronic kidney disease as a result of chronic laxative abuse from a purging type of anorexia nervosa (AN-P), developed an anuric AKI requiring hemodialysis and a mild AKI 2 months later. Both episodes of AKI involved severe to moderate hypokalemia (1.2 and 2.7 mmol/L, respectively), volume depletion, and mild rhabdomyolysis. The histologic findings of the first AKI revealed the remnants of acute tubular necrosis with advanced chronic tubulointerstitial nephritis and ischemic glomerular injury. Along with these observations, the intertwined relationship among precipitants of recurrent AKI in AN-P is discussed, and then we postulate a contributory role of hypokalemia involved in the pathophysiology of the renal ischemia-induced AKI.

Renal complications in anorexia nervosa

PURPOSE

Anorexia nervosa is a malady with possible long-lasting physiological consequences. Among these, little is known about the renal effects, which remain rarely investigated.

METHODS

A literature review was conducted using electronic databases and manual search of relevant articles, discussing the renal impacts of anorexia nervosa.

RESULTS

Renal failure has been described in malnourished patients, but the optimal non-invasive tool to assess the glomerular function rate in this population needs to be further evaluated. Significant disruptions in osmolar regulation, even in the absence of potomania, arise from multiple factors: hypothalamic dysfunction, intrinsic renal insufficiency, and use of psychotropic medications. Urinary urgency and nocturnal enuresis are frequent symptoms, rarely reported by patients. Among hydroelectrolytic disorders, hypokalemia is the most frequent, especially in settings of vomiting or medication misuse. Hyponatremia, hypomagnesemia, and hypophosphatemia may also be encountered. Urinary lithiases are relatively frequent as a consequence of dehydration, laxative use, or both.

CONCLUSION

Investigation and follow-up of the renal function are essential in patients with an eating disorder, especially when the illness has been present for a long time.

Traditional and novel dietary interventions for preventing progression of chronic kidney disease

Treatment of chronic kidney disease (CKD) and its complications remain largely unresolved. Currently used treatments include blood pressure control and the use of angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs), which can slow down the progression of CKD but are unable to halt or reverse it. Dietary protein restriction represents an additional therapeutic measure used to slow the progression of CKD. The putative mechanisms of action responsible for its therapeutic effects include beneficial hemodynamic effects and the limitation of absorbable protein breakdown products that could lead to the accumulation of uremic waste and consequent various deleterious effects. The practical implementation of protein restriction through dietary intervention has been hindered on multiple levels, including patient nonadherence, lack of health care resources, and concerns related to adverse effects associated with the development of protein-energy wasting (PEW). As a result, alternative interventions have been designed to address some or all of these shortcomings and concerns. One such intervention is the administration of medications that prevent the absorption of protein catabolic products from the gut. This article reviews the various interventions using such a strategy to prevent or slow the progression of CKD, with special focus on recent advances in this field.

Hypokalemia, its contributing factors and renal outcomes in patients with chronic kidney disease

BACKGROUND

In the chronic kidney disease (CKD) population, the impact of serum potassium (sK) on renal outcomes has been controversial. Moreover, the reasons for the potential prognostic value of hypokalemia have not been elucidated.

DESIGN PARTICIPANTS & MEASUREMENTS

2500 participants with CKD stage 1-4 in the Integrated CKD care program Kaohsiung for delaying Dialysis (ICKD) prospective observational study were analyzed and followed up for 2.7 years. Generalized additive model was fitted to determine the cutpoints and the U-shape association between sK and end-stage renal disease (ESRD). sK was classified into five groups with the cutpoints of 3.5, 4, 4.5 and 5 mEq/L. Cox proportional hazard regression models predicting the outcomes were used.

RESULTS

The mean age was 62.4 years, mean sK level was 4.2±0.5 mEq/L and average eGFR was 40.6 ml/min per 1.73 m(2). Female vs male, diuretic use vs. non-use, hypertension, higher eGFR, bicarbonate, CRP and hemoglobin levels significantly correlated with hypokalemia. In patients with lower sK, nephrotic range proteinuria, and hypoalbuminemia were more prevalent but the use of RAS (renin-angiotensin system) inhibitors was less frequent. Hypokalemia was significantly associated with ESRD with hazard ratios (HRs) of 1.82 (95% CI, 1.03-3.22) in sK <3.5mEq/L and 1.67 (95% CI,1.19-2.35) in sK = 3.5-4 mEq/L, respectively, compared with sK = 4.5-5 mEq/L. Hyperkalemia defined as sK >5 mEq/L conferred 1.6-fold (95% CI,1.09-2.34) increased risk of ESRD compared with sK = 4.5-5 mEq/L. Hypokalemia was also associated with rapid decline of renal function defined as eGFR slope below 20% of the distribution range.

CONCLUSION

In conclusion, both hypokalemia and hyperkalemia are associated with increased risk of ESRD in CKD population. Hypokalemia is related to increased use of diuretics, decreased use of RAS blockade and malnutrition, all of which may impose additive deleterious effects on renal outcomes.

Anorexia nervosa and the kidney

Anorexia nervosa is a common psychiatric disorder that disproportionately affects adolescents and young adults and is associated with high rates of morbidity and mortality. Anorexia nervosa can affect the kidney in numerous ways, including increased rates of acute kidney injury and chronic kidney disease, electrolyte abnormalities, and nephrolithiasis. Additionally, the diagnosis and treatment of anorexia nervosa-associated kidney diseases are challenging, reflecting complications such as refeeding syndrome, as well as the limitations of serum creatinine level in this population to estimate kidney function and the psychosocial challenges inherent with treating systemic manifestations of psychiatric conditions. In this review, we discuss kidney diseases and kidney-associated conditions that occur in individuals with anorexia nervosa, summarizing many of the challenges in treating patients with this disease.

Association of hypo- and hyperkalemia with disease progression and mortality in males with chronic kidney disease: the role of race

BACKGROUND/AIMS

Abnormal serum potassium is associated with higher mortality in dialysis patients, but its impact on outcomes in predialysis chronic kidney disease (CKD) is less clear. Furthermore, blacks with normal kidney function have lower urinary potassium excretion, but it is unclear if such differences have a bearing on race-associated outcomes in CKD.

METHODS

We studied predialysis mortality and slopes of estimated glomerular filtration rate, eGFR) associated with serum potassium in 1,227 males with CKD. Mortality was examined in time-dependent Cox models, and slopes of eGFR in linear mixed effects models with adjustments for case mix and laboratory values.

RESULTS

Both hypo- and hyperkalemia were associated with mortality overall and in 933 white patients, but in 294 blacks hypokalemia was a stronger death predictor. Hypokalemia was associated with loss of kidney function independent of race: a 1 mEq/l lower potassium was associated with an adjusted difference in slopes of eGFR of -0.13 ml/min/1.73 m(2)/year (95% CI: -0.20 to -0.07), p < 0.001.

CONCLUSION

Hypo- and hyperkalemia are associated with higher mortality in CKD patients. Blacks appear to better tolerate higher potassium than whites. Hypokalemia is associated with faster CKD progression independent of race. Hyperkalemia management may warrant race-specific consideration, and hypokalemia correction may slow CKD progression.

Does hypokalaemia cause nephropathy? An observational study of renal function in patients with Bartter or Gitelman syndrome

BACKGROUND

Hypokalaemic nephropathy has been described in patients with chronic potassium depletion; it is a condition in which proximal tubular vacuolization and interstitial fibrosis occur, resulting in a decline in glomerular filtration rate (GFR) and, in some cases, renal failure. It has been described in patients with chronic diarrhoea, eating disorders, laxative abuse and primary hyperaldosteronism; also occasionally in Bartter syndrome (BS), in which severe hypokalaemia accompanies significant renal sodium and water losses, though rarely in Gitelman syndrome (GS), in which there is equally severe hypokalaemia, but only modest sodium losses.

AIM

We hypothesized that hypokalaemic nephropathy may not be due to potassium depletion per se, but persistently elevated circulating levels of aldosterone, possibly with superimposed episodes of renal hypoperfusion.

DESIGN AND METHODS

We searched UK and European data sets to retrospectively compare serum and urinary parameters in patients with GS and BS.

RESULTS

The patients with GS often had lower serum potassium concentrations than patients with BS, but the BS patients had significantly higher serum creatinine concentrations and lower estimated GFRs (eGFR). BS patients had significantly higher fractional excretions of sodium compared with GS patients, as well as higher plasma renin activities and serum aldosterone levels.

CONCLUSION

These findings show that in genetically confirmed cases of BS and GS, the degree of hypokalaemia (as an index of chronic potassium depletion) does not correlate with GFR, and that on-going sodium and water losses, and consequent secondary hyperaldosteronism, may play a more important role in the aetiology of hypokalaemic nephropathy.

Hypomagnesemia is a risk factor for nonrecovery of renal function and mortality in AIDS patients with acute kidney injury

The objective of the present study was to determine the prevalence of electrolyte disturbances in AIDS patients developing acute kidney injury in the hospital setting, as well as to determine whether such disturbances constitute a risk factor for nephrotoxic and ischemic injury. A prospective, observational cohort study was carried out. Hospitalized AIDS patients were evaluated for age; gender; coinfection with hepatitis; diabetes mellitus; hypertension; time since HIV seroconversion; CD4 count; HIV viral load; proteinuria; serum levels of creatinine, urea, sodium, potassium and magnesium; antiretroviral use; nephrotoxic drug use; sepsis; intensive care unit (ICU) admission, and the need for dialysis. Each of these characteristics was correlated with the development of acute kidney injury, with recovery of renal function and with survival. Fifty-four patients developed acute kidney injury: 72% were males, 59% had been HIV-infected for >5 years, 72% had CD4 counts <200 cells/mm(3), 87% developed electrolyte disturbances, 33% recovered renal function, and 56% survived. ICU admission, dialysis, sepsis and hypomagnesemia were all significantly associated with nonrecovery of renal function and with mortality. Nonrecovery of renal function was significantly associated with hypomagnesemia, as was mortality in the multivariate analysis. The risks for nonrecovery of renal function and for death were 6.94 and 6.92 times greater, respectively, for patients with hypomagnesemia. In hospitalized AIDS patients, hypomagnesemia is a risk factor for nonrecovery of renal function and for in-hospital mortality. To determine whether hypomagnesemia is a determinant or simply a marker of critical illness, further studies involving magnesium supplementation in AIDS patients are warranted.

Hypokalemic rhabdomyolysis in a child with Bartter's syndrome

Hypokalemia represents a rare cause of rhabdomyolysis. Some reports have described a few adult patients affected by Bartter's syndrome and Gitelman's syndrome with rhabdomyolysis due to severe hypokalemia. We report the first pediatric patient with Bartter's syndrome in whom rhabdomyolysis developed when her plasma potassium level was less than 2 mEq/l. Prompt intravenous fluid and potassium prevented tubular damage and acute renal failure. We recommend determining serum creatine phosphokinase in all patients affected by Bartter's syndrome and profound hypokalemia.

Medullary nephrocalcinosis associated with long-term furosemide abuse in adults

BACKGROUND

The use of furosemide is well recognized as a predisposing factor of nephrocalcinosis in infants. Although furosemide is widely used for various medical conditions in adults, its association with nephrocalcinosis in adults is not well established.

METHODS

We studied 18 consecutive adult patients (male:female ratio 1:17, age range 21-59 years) who habitually took furosemide to control weight or oedema for long periods of time (range 3-25 years). The daily dose of continuous intake of furosemide ranged from 40 to 2800 mg. Nephrocalcinosis was evaluated using renal ultrasonography (US), computed tomography (CT), or kidney biopsies.

RESULTS

Renal US and CT revealed bilateral nephrocalcinosis of the medullary pyramids in 15 (83.3%) out of 18 patients. The duration of furosemide abuse was similar between nephrocalcinosis positive (NC(+)) and nephrocalcinosis negative (NC(-)) groups. The daily dose of furosemide was nearly 10 times higher in the NC(+) group (range 120-2800 mg, mean 538 mg) than the NC(-) group (range 40-80 mg, mean 67 mg). All patients showed variable degrees of renal insufficiency and there was no difference in creatinine clearance between the NC(+) and NC(-) groups (P>0.05). Kidney biopsies performed in three patients showed focal tubulo-interstitial fibrosis and atrophy and calcifications were observed in outer medullary tubulo-interstitium.

CONCLUSIONS

Long-term furosemide abuse can cause medullary nephrocalcinosis in adults, and the risk of developing of nephrocalcinosis seems to be correlated with the daily dose of furosemide. We suggest that long-term furosemide abuse should be suspected in adult patients when medullary nephrocalcinosis is incidentally detected by US or CT.