Secondary oxalosis in chronic renal insufficiency

Selenium Status in Patients with Chronic Liver Disease: A Systematic Review and Meta-Analysis

Background: The potential role of selenium in preventing chronic liver diseases remains controversial. This meta-analysis aimed to summarize the available evidence from observational studies and intervention trials that had evaluated the associations between body selenium status and chronic liver diseases. Methods: We comprehensively searched MEDLINE, Embase, Web of Science, and Cochrane Library from inception to April 2021. The study protocol was registered at PROSPERO (CRD42020210144). Relative risks (RR) for the highest versus the lowest level of selenium and standard mean differences (SMD) with 95% confidence intervals (CI) were pooled using random-effects models. Heterogeneity and publication bias were evaluated using the I² statistic and Egger’s regression test, respectively. Results: There were 50 studies with 9875 cases and 12975 population controls in the final analysis. Patients with hepatitis (SMD = −1.78, 95% CI: −2.22 to −1.34), liver cirrhosis (SMD = −2.06, 95% CI: −2.48 to −1.63), and liver cancer (SMD = −2.71, 95% CI: −3.31 to −2.11) had significantly lower selenium levels than controls, whereas there was no significant difference in patients with fatty liver diseases (SMD = 1.06, 95% CI: −1.78 to 3.89). Moreover, the meta-analysis showed that a higher selenium level was significantly associated with a 41% decrease in the incidence of significant advanced chronic liver diseases (RR = 0.59, 95% CI: 0.49 to 0.72). Conclusion: Our meta-analysis suggested that both body selenium status and selenium intake were negatively associated with hepatitis, cirrhosis, and liver cancer. However, the associations for fatty liver diseases were conflicting and need to be established in prospective trials.

Nutrition in alcohol-related liver disease: Physiopathology and management

Malnutrition encompassing both macro- and micro-nutrient deficiency, remains one of the most frequent complications of alcohol-related liver disease (ArLD). Protein-energy malnutrition can cause significant complications including sarcopenia, frailty and immunodepression in cirrhotic patients. Malnutrition reduces patient’s survival and negatively affects the quality of life of individuals with ArLD. Moreover, nutritional deficit increases the likelihood of hepatic decompensation in cirrhosis. Prompt recognition of at-risk individuals, early diagnosis and treatment of malnutrition remains a key component of ArLD management. In this review, we describe the pathophysiology of malnutrition in ArLD, review the screening tools available for nutritional assessment and discuss nutritional management strategies relevant to the different stages of ArLD, ranging from acute alcoholic hepatitis through to decompensated end stage liver disease.

Erythrocyte membrane lipids and serum selenium in post-viral and alcoholic cirrhosis

Erythrocyte-membrane fatty acid composition and cholesterol content were evaluated along with serum selenium in 33 patients with liver cirrhosis and in 40 normal subjects. Thirteen patients were suffering from post-viral (group V) and 20 from alcoholic (group A) cirrhosis. The aim of the study was to elucidate whether membrane lipid abnormalities in cirrhosis were linked to the aetiology of the disease or whether they were the results of the cirrhotic process itself. The patients presented a significant increase in membrane cholesterol, palmitic acid (C16:0) and saturated fatty acids (SFA), and a decrease in polyunsaturated fatty acids (PUFA) and polyunsaturated/saturated fatty acids ratio (P/S) compared with the control group. Serum selenium levels were significantly reduced. When patients were subdivided according to aetiology, the alcoholic patients showed greater lipid composition abnormalities than the viral cirrhotics (higher levels of SFA and lower PUFA and P/S), while pathologic palmitic acid, membrane cholesterol and serum selenium values were confirmed in both groups of patients. In conclusion, low serum selenium and a series of erythrocytes membrane lipid composition abnormalities would appear to be features peculiar to cirrhosis. Alcoholic cirrhotics, on the other hand, show a more deranged erythrocyte membrane lipid profile.

Implication of free radical mechanisms in ethanol-induced cellular injury

Numerous experimental data reviewed in the present article indicate that free radical mechanisms contribute to ethanol-induced liver injury. Increased generation of oxygen- and ethanol-derived free radicals has been observed at the microsomal level, especially through the intervention of the ethanol-inducible cytochrome P450 isoform (CYP2E1). Furthermore, an ethanol-linked enhancement in free radical generation can occur through the cytosolic xanthine and/or aldehyde oxidases, as well as through the mitochondrial respiratory chain. Ethanol administration also elicits hepatic disturbances in the availability of non-safely-sequestered iron derivatives and in the antioxidant defense. The resulting oxidative stress leads, in some experimental conditions, to enhanced lipid peroxidation and can also affect other important cellular components, such as proteins or DNA. The reported production of a chemoattractant for human neutrophils may be of special importance in the pathogenesis of alcoholic hepatitis. Free radical mechanisms also appear to be implicated in the toxicity of ethanol on various extrahepatic tissues. Most of the experimental data available concern the gastric mucosa, the central nervous system, the heart, and the testes. Clinical studies have not yet demonstrated the role of free radical mechanisms in the pathogenesis of ethanol-induced cellular injury in alcoholics. However, many data support the involvement of such mechanisms and suggest that dietary and/or pharmacological agents able to prevent an ethanol-induced oxidative stress may reduce the incidence of ethanol toxicity in humans.

Biochemical markers of hepatic fibrosis

Most liver diseases lead to a pathobiochemical reaction termed liver fibrosis. This is a dynamic process implying different rates of progression or regression. Thus, histological examination of a liver biopsy is essential for a diagnosis but biochemical tests are necessary for assessing the activity of the process and monitoring its evolution. We review the most important constituents of liver connective tissue and the biochemical tests developed for evaluating liver fibrosis. The aminopeptide of type III procollagen is the most widely used parameter: two different radioimmunoassays have been developed with different affinities for the two circulating forms of the molecule. The determination of serum P3P reveals an elevation of blood levels both in acute and chronic liver diseases. In the first, serum P3P is an index of hepatic necrosis and inflammation which correlates with other biochemical parameters. In the second it is an index of active fibrogenesis. Moreover, in primary biliary cirrhosis this parameter is an independent prognostic variable and an important predictor of survival. Other immunoassays exist for different collagen cleavage products, but their clinical value is not established. Laminin and fibronectin are the principal structural glycoproteins in liver. Fibronectin determination does not seem to be of clinical value in liver disease. In contrast, serum laminin correlates with the severity of portal venous pressure in advanced liver disease. Its concentration parallels the severity of varices and may indicate the risk of bleeding. Hyaluronate is a high molecular weight polysaccharide, raised serum concentrations reflect both its increased synthesis by activated fibroblasts and its impaired catabolism by the liver. Thus, it may be useful for evaluating and monitoring the progression of chronic liver disease. The measurement of the activity of prolyl 4-hydroxylase as well as that of lysine oxidase and other enzymes has been proposed, but their clinical value is not sufficiently demonstrated. A panel of tests (e.g., laminin, hyaluronate and the aminopeptide of type III procollagen) seems to be recommended for a biochemical assessment of liver fibrosis in clinical practice.

Effects of selenium supplementation on blood and urine selenium levels and liver function in patients with primary biliary cirrhosis

To study the mechanism of the reduced serum selenium concentration in patients with liver damage we administered 200 micrograms (2.53 mumol) selenium daily as selenium-rich yeast to 8 patients with primary biliary cirrhosis and 8 healthy controls over 16 weeks. Initially selenium concentrations in serum were 24% lower (P less than 0.001) in patients than controls. During supplementation serum selenium levels increased in both groups but the difference between them persisted. Throughout the study whole blood selenium levels and glutathione peroxidase activities were also somewhat lower (P = NS) in patients than controls. Selenium supplementation had no effect on whole blood glutathione peroxidase activities in either group. The basal 24 h urinary excretion of selenium was similar in both groups but was increased more by supplementation in patients than controls. Selenium administration did not influence the liver function of the patients. We conclude that impaired hepatic production of selenium-containing serum compounds is the most likely explanation for the reduced serum selenium concentration in patients with primary biliary cirrhosis.

Serum selenium in liver cirrhosis: correlation with markers of fibrosis

In 55 patients with alcoholic cirrhosis and in 47 healthy individuals we assayed the concentration of selenium in serum (S-Se) by proton induced X-ray emission, the aminoterminal peptide of type III procollagen (NPIIIP) by RIA and the plasma fibronectin (FN) by immuno-nephelometry, together with routine biochemical tests. S-Se was lower in cirrhosis than in controls (0.57, SD 0.20 vs 0.92, SD 0.16 mumol/l; p less than 0.001) and was more reduced in ascitic than in compensated patients (0.50, SD 0.19 vs 0.66, SD 0.17 mumol/l; p less than 0.001). Regression analysis showed a positive correlation of S-Se with serum albumin and FN, whereas necrotic or inflammatory activity seems unrelated to S-Se; a negative correlation was found between S-Se and NPIIIP, suggesting a protective role of selenium against fibrosis.

Blood and liver selenium concentrations in patients with liver diseases

To study the relation between blood and liver selenium levels in hepatic disorders we measured the selenium concentrations of whole blood, serum and liver tissue obtained at laparoscopy in 17 patients with different kinds of liver diseases. As compared to healthy controls the mean concentration of selenium was decreased by 24% (p less than 0.001) in the whole blood of the patients (n = 15). Similarly, the mean concentration of selenium in serum was 35% lower in the patients than in the controls (p less than 0.001). As compared to the control samples obtained at autopsy the selenium content of liver was decreased by 13% (p less than 0.05) in the patients. Significant positive correlations were found between the selenium content of the liver and the whole blood (r = 0.62, p less than 0.05) as well as also between liver and serum (r = 0.52, p less than 0.05) selenium concentrations. In conclusion, the present study suggests that in patients with liver disorders the selenium concentrations are decreased not only in the blood but also in the liver tissue. Whether this means a decreased activity of hepatic glutathione peroxidase and, further, an increased possibility of oxidative cell injury, remains open.

Evidence that serum calcium oxalate supersaturation is a consequence of oxalate retention in patients with chronic renal failure

Serum oxalate rises in uremia because of decreased renal clearance, and crystals of calcium oxalate occur in the tissues of uremic patients. Crystal formation suggests that either uremic serum is supersaturated with calcium oxalate, or local oxalate production or accumulation causes regional supersaturation. To test the first alternative, we ultrafiltered uremic serum and measured supersaturation with two different methods previously used to study supersaturation in urine. First, the relative saturation ratio (RSR), the ratio of the dissolved calcium oxalate complex to the thermodynamic calcium oxalate solubility product, was estimated for 11 uremic (before and after dialysis) and 4 normal serum samples using a computer program. Mean ultrafiltrate oxalate predialysis was 89 +/- 8 microM/liter (+/- SEM), 31 +/- 4 postdialysis, and 10 +/- 3 in normals. Mean RSR was 1.7 +/- 0.1 (predialysis), 0.7 +/- 0.1 (postdialysis), and 0.2 +/- 0.1 (normal), where values greater than 1 denote supersaturation, less than 1, undersaturation. Second, the concentration product ratio (CPR), the ratio of the measured calcium oxalate concentration product before to that after incubation of the sample with calcium oxalate monohydrate crystal, was measured in seven uremic and seven normal serum ultrafiltrates. Mean oxalate was 91 +/- 11 (uremic) and 8 +/- 3 (normal). Mean CPR was 1.4 +/- 0.2 (uremic) and 0.2 +/- 0.1 (normal). Predialysis, 17 of 18 uremic ultrafiltrates were supersaturated with respect to calcium oxalate. The degree of supersaturation was correlated with ultrafiltrate oxalate (RSR, r = 0.99, r = 29, P less than 0.001; CPR, r = 0.75, n = 11, P less than 0.001). A value of ultrafiltrate oxalate of 50 microM/liter separated undersaturated from supersaturated samples and occurred at a creatinine of approximately 9.0 mg/dl.

Decreased serum selenium in alcoholics--a consequence of liver dysfunction

The serum concentration of selenium was decreased by 17 and 48% in non-cirrhotic and cirrhotic alcoholics, respectively, as compared to healthy controls. In these alcoholics the serum selenium correlated positively with the serum albumin and plasma prothrombin time and inversely with the serum bilirubin, alkaline phosphatase and gamma-glutamyl transpeptidase. Abstinence from ethanol for two weeks was without effect on the serum selenium level in non-cirrhotic alcoholics and acute alcohol intake did not change the serum selenium concentration in non-alcoholic volunteers. In patients with primary biliary cirrhosis the serum concentration of selenium was similar to that in the alcoholic cirrhotics. In patients with hypoalbuminaemia of renal origin the serum selenium was normal. In conclusion our results show that the deterioration of liver function, irrespective of its aetiology, leads to the decrease in serum selenium levels. Whether a defect in removal of lipoperoxides is associated with this decrease in serum selenium concentration remains to be decided by further studies.

Serum selenium levels in liver diseases

A possible pathogenetic role of selenium deficiency in alcoholic cirrhosis of the liver has previously been discussed. In the present study serum selenium was analyzed in 5 groups of liver diseases. The method used for selenium determination was electrothermal atomic absorption, after thermal stabilization of selenium compounds by addition of nickel nitrate. The selenium level of a reference group of healthy Norwegian adults (n = 40) was 1.53 +/- 0.25 mumol/l. The serum concentrations of selenium in patients suffering from alcoholic cirrhosis, chronic active hepatitis and chronic persistent hepatitis were lowered to 40-80 per cent of those of the reference group. In alcoholic cirrhosis and chronic active hepatitis the decreased serum selenium concentrations were significantly correlated to decreased levels of albumin and prealbumin.