Potassium status of patients with cirrhosis

The impact of acute kidney injury on mortality and clinical outcomes in patients with alcoholic cirrhosis in the USA

INTRODUCTION

Acute kidney injury (AKI) is associated with increased morbidity and mortality in patients with chronic liver disease. Although the impact of AKI on patients with liver disease has been established, its impact on alcoholic cirrhosis has not been studied.

METHODS

Our study utilized data from the National Inpatient Sample for the year 2016 for all patients with a diagnosis of alcoholic cirrhosis and AKI. Primary outcomes were mortality, length of stay (LOS) and hospitalization cost were compared. Secondary outcomes were complications of cirrhosis and its impact on mortality. Multivariate logistic regression analysis and propensity-score matching were used to compare the two groups.

RESULTS

A total of 29 906 patients were included and 6733 (22.5%) had AKI. Propensity-matched multivariate analysis demonstrates that AKI was associated with a significant increase risk of mortality [odds ratio (OR): 8.09; 95% confidence interval (CI), 6.68-9.79; P < 0.0001]. AKI prolonged the hospital stay by 3.68 days (95% CI, 3.42-3.93; P < 0.0001) and increased total hospital charges by $50 284 (95% CI, 45 829-54 739; P < 0.0001). AKI increased the risk of complications of cirrhosis, including hepatorenal syndrome (OR: 19.15; 95% CI, 16.1-22.76), ascites (OR: 2.27; 95% CI, 2.11-2.44), hepatic encephalopathy (OR: 2.54; 95% CI, 1.87-3.47) and portal hypertension (OR: 1.08; 95% CI, 1.01-1.16).

CONCLUSION

AKI in alcoholic cirrhosis significantly increases the risk of mortality, hospitalizations costs and LOS. Further studies are needed on addressing renal failure and treatment options for patients with alcoholic cirrhosis.

Murine epithelial sodium (Na+) channel regulation by biliary factors

The epithelial sodium channel (ENaC) mediates Na+ transport in several epithelia, including the aldosterone-sensitive distal nephron, distal colon, and biliary epithelium. Numerous factors regulate ENaC activity, including extracellular ligands, post-translational modifications, and membrane-resident lipids. However, ENaC regulation by bile acids and conjugated bilirubin, metabolites that are abundant in the biliary tree and intestinal tract and are sometimes elevated in the urine of individuals with advanced liver disease, remains poorly understood. Here, using a Xenopus oocyte-based system to express and functionally study ENaC, we found that, depending on the bile acid used, bile acids both activate and inhibit mouse ENaC. Whether bile acids were activating or inhibiting was contingent on the position and orientation of specific bile acid moieties. For example, a hydroxyl group at the 12-position and facing the hydrophilic side (12α-OH) was activating. Taurine-conjugated bile acids, which have reduced membrane permeability, affected ENaC activity more strongly than did their more membrane-permeant unconjugated counterparts, suggesting that bile acids regulate ENaC extracellularly. Bile acid-dependent activation was enhanced by amino acid substitutions in ENaC that depress open probability and was precluded by proteolytic cleavage that increases open probability, consistent with an effect of bile acids on ENaC open probability. Bile acids also regulated ENaC in a cortical collecting duct cell line, mirroring the results in Xenopus oocytes. We also show that bilirubin conjugates activate ENaC. These results indicate that ENaC responds to compounds abundant in bile and that their ability to regulate this channel depends on the presence of specific functional groups.

Urinary potassium loss in children with acute liver failure and acute viral hepatitis

OBJECTIVES

The aim of the present study was to determine urinary potassium (K⁺) loss (as measured by fractional excretion of K⁺ [FEK] and transtubular K⁺ gradient [TTKG]) in children with acute liver failure (ALF) and acute viral hepatitis (AVH) at the time of presentation to the hospital and day 45 of follow-up.

METHODS

Twenty-five patients with ALF and 84 patients with AVH were worked up for clinical features, liver function tests, and hepatitis viral infections and monitored for outcome. All of the patients with ALF were hospitalized. FEK and TTKG were estimated on the day patients were first seen in the hospital or hospitalized and later on day 45 of follow-up.

RESULTS

Sixty percent (15/25) of patients with ALF were hypokalemic (serum K⁺ <3.5 mEq/L) as compared with only 12% (10/84) in the AVH group (P = 0.000) at the time of presentation in the hospital. Inappropriate kaliuresis was present in 80% to 100% of hypokalemic children compared with 0% to 30% of normokalemic individuals at the time of first contact in either the ALF or AVH group. Inappropriate urinary K⁺ loss and serum K⁺ levels in the hypokalemic individuals improved as the hepatic functions recovered by day 45 of follow-up (P = 0.014-0.000). No significant change in kaliuresis was observed among normokalemic subjects between first contact and later on day 45 of follow-up (P = 0.991-0.228). Despite different physiologic mechanisms, appropriateness of kaliuresis measured by FEK and TTKG showed results in the same direction.

CONCLUSIONS

Hypokalemia and inappropriate kaliuresis observed during the acute phase of ALF and AVH reversed with clinical and biochemical recovery. In the absence of major gastrointestinal losses and renal abnormalities, there is need to investigate the contributory role of factors like hyperaldosteronism and food intake, which may have therapeutic implications.

Clinical significance in alcoholic patients of commonly encountered laboratory test results

An improved understanding of medical problems of alcoholic patients can be gained from commonly encountered laboratory test results. Liver function tests--such as measures of alkaline phosphatase, gamma-glutamyl transpeptidase, aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase--may provide evidence of altered hepatic activity of different types, such as obstruction and hepatocellular injury. Other test results may indicate impaired hepatic function, such as measurements of albumin, bilirubin, prothrombin time, and blood urea nitrogen. Alterations are also common in electrolytes, blood glucose, magnesium, phosphate, uric acid, and acid-base balance. Disturbances in hematologic function are not infrequent in alcoholic patients, including anemias from many causes, altered granulocyte responses, and thrombocytopenia.

Spironolactone: a re-examination

A review of the aldosterone antagonist spironolactone is presented. It is effective both as monotherapy and in combination with other hypotensive agents in the control of both essential and hyperaldosterone-induced hypertension. It is useful as a diuretic in conditions such as cirrhosis and congestive heart failure, and is most commonly employed because of its potassium- and magnesium-sparing qualities. Spironolactone also has been used as an antiandrogenic agent in managing hirsutism. Its adverse effect profile, considered somewhat prohibitive in the past, is generally not significant when reasonably low doses (less than 150 mg/d) are used.

Disorders of the serum electrolytes, acid-base balance, and renal function in alcoholism

This chapter reviews the disturbances of the serum sodium and potassium concentrations, acid-base imbalances, and acute renal dysfunction that are seen frequently in alcoholic patients. The hyponatremia common in decompensated cirrhotics is caused by an impairment of renal free water clearance and concomitant water ingestion. Excessive proximal renal tubular sodium reabsorption and nonosmotic vasopressin release underlie the defect in renal water excretion in cirrhosis. Restriction of water intake is the principal therapeutic measure for hyponatremia. Hypokalemia is common in alcoholics but when observed does not always represent true potassium depletion. Although most cirrhotics have a diminished total body potassium content, intracellular potassium concentration is usually normal. In some patients gastrointestinal and renal potassium losses and nutritional potassium deficiency may cause true potassium depletion. Respiratory and metabolic alkalosis are the acid-base disturbances seen most frequently in alcoholics. Acidosis is relatively uncommon and is usually due to renal insufficiency, lactic acid or keto-acid accumulation. Toxin ingestion (methanol, ethylene glycol, or isopropanol) may also cause severe acidosis. Rhabdomyolysis, common in severe alcoholism, may produce various electrolyte disturbances and acute renal failure. The prognosis for recovery is good although temporary dialysis may be necessary.

Intracellular and exchangeable potassium in cirrhosis. Evidence against the occurrence of potassium depletion in cirrhosis with ascites

The intracellular potassium content of leukocytes, the extracellular fluid volume (82Br space), and exchangeable potassium were determined in 28 patients with cirrhosis of the liver (18 with ascites) and in 15 hospitalized controls. No intracellular potassium depletion could be identified in these patients. Leukocyte potassium was similar in cirrhotic patients with and without ascites (355.9 +/- 25.3 and 348.1 +/- 31.9 mEq/kg of dry solids, respectively) and in hospitalized controls (359.7 +/- 27.4) (mean +/- SD). The extracellular fluid volume was similar in controls and cirrhotics without ascites, but markedly increased in cirrhotics with ascites. The exchangeable potassium (mEq/kg of body weight) was similar in nonascitic cirrhotics and in hospitalized controls, but significantly lower in patients with cirrhosis and ascites. However, when the estimated weight of the extracellular fluid volume was substrated from the total body weight, thus obviating the influence of the increased extracellular fluid volume of ascitic patients in the body weight, the exchangeable potassium (mEq/kg of "corrected" body weight) was similar in cirrhosis with ascites (52.9 +/- 6.7 mEq/kg), nonascitic cirrhotics (55.8 +/- 6.1 mEq/kg) and hospitalized controls (55.0 +/- 8.3 mEq/kg), and a significant correlation was obtained between the exchangeable potassium and the leukocyte potassium content. In five patients, the measurements were repeated after relieving ascites with diuretics. No change was observed in the leukocyte potassium, but exchangeable potassium (mEq/kg of body weight) increased, reaching values not significantly different from controls or nonascitic cirrhotics. The exchangeable potassium (mEq/kg of "correct" body weight) did not change. Our results strongly suggest that potassium depletion was not present in the series of cirrhotic patients studied.

Total body water, extracellular water, plasma volume, and total body potassium in cirrhosis of the liver

Extracellular water (EWC; 82-bromide), total body water (TBW; 3-THO), intracellular water (ICW = TBW-ECW), plasma volume (PV; 51-Cr), and total body potassium (TBK; 40-K) were studied in patients with cirrhosis of the liver (n = 12) and in controls (n = 12). ECW (39%), TBW (28%), ICW (19%), and PV (24%) increased, TBK (28%) however, decreased in cirrhosis. The results indicate that it is less the lean body mass, but rather the intracellular potassium concentration that is lowered (cirrhosis: 84 +/- 21 mmol/l ICW; controls: 115 +/- 23 mmol/l ICW). Decreased potassium per cell (mmol) and increased intracellular water are discussed as possible reasons for this. The correlation between TBK (%) and serum potassium (mmol/l) was found to be r = 0.56 (p less than 0.002). Correlations between the biochemical parameters gamma-globulins, cholin esterase, serum sodium and serum albumin (g/l PV) and characteristic fluid disturbances in cirrhosis are highly significant whereas albumin (g/kg bodyweight) was the same in both groups. We can support the 'overflow theory' of ascites formation.

Changes in the electrolyte content of leucocytes at different clinical stages of cirrhosis

The intracellular sodium, potassium, and water content of isolated leucocytes was estimated in 47 patients with cirrhosis. The values for sodium showed a wide scatter. In patients without ascites the mean value was significantly increased but in those accumulating ascites it was normal, although often reduced in individual subjects. Reduced values were found in patients with hyponatraemia associated with end-stage cirrhosis and diuretic treatment. Changes in leucocyte water content closely followed those in sodium content. Leucocyte potassium content was normal except in patients accumulating ascites in whom it was significantly reduced, indicating whole body depletion, and this could be corrected by administration of spironolactone.

Studies on the activity of the renin-angiotensin-aldosterone system (RAAS) in patients with cirrhosis of the liver

Plasma renin activity (PRA), plasma renin concentration (PRC), angiotensinogen, angiotensin II (AT II) and plasma aldosterone were determined by radioimmunoassay in 77 patients with cirrhosis of the liver [group I: with ascites, untreated (n=23); group II: patients with ascites during treatment (n=32); group III: after removal of fluids, but under further spironolactone therapy (n=10); group IV: untreated subjects without ascites (n=12)]. With the exception of decreased angiotensinogen values in all groups ranging between 39% (group IV) and 73% (group III) no significant changes of the other parameters of the RAAS were found in untreated patients. A highly significant increase of PRA, PRC, AT II and plasma aldosterone was observed in treated cirrhotics with (group II) or without (group III) ascites. In the total series of patients AT II was closely related to PRA, PRC and aldosterone emphasizing aldosterone secretion. Plasma sodium was inversely correlated to PRA, PRC, AT II and aldosterone, but no relationship was detected between these parameters of the RAAS and plasma potassium. Our results indicate that hyperaldosteronism in cirrhosis appears unlikely to be the major determinant of avid renal sodium retention and ascites formation. An increased activity of the RAAS is most often initiated by therapeutic factors and/or markedly altered electrolyte metabolism. Therefore, basal conditions of the patients to be studied must be well defined to exclude any artificially induced stimulation of the RAAS.

Potassium and magnesium depletion in patients with cirrhosis on maintenance diuretic regimens

Total body potassium (40K) and leucocyte potassium measurements were carried out on 19 patients with stable but decompensated cirrhosis maintained on diuretics for previous ascites. Of 13 patients receiving spironolactone alone none had a total body potassium below the expected lower limit of normal, whereas, of six receiving additional frusemide, two had low values. The results for leucocyte potassium were in agreement and simultaneous measurements of leucocyte magnesium showed a close correlation, those with intracellular potassium depletion also having magnesium depletion. One such patient was treated with magnesium supplements without effect on the potassium, although intracellular magnesium was improved. It is concluded that spironolactone alone is the treatment of choice in the maintenance management of such patients; that additional potassium would be unnecessary; and that additional frusemide should be avoided if possible.