Study of Zinc in Cirrhosis of Liver

Transcription

1 74 Clinical Study Study of Zinc in Cirrhosis of Liver Kaushik Kar, Assistant Professor, Gorachand Bhattyacharya, Professor Department of Biochemistry, Calcutta National Medical College, Kolkata. Jayanta De, Professor and HOD, Department of Biochemistry, Midnapore Medical College, Midnapore. Abstract 73 liver cirrhosis patients have been selected. Serum zinc and albumin levels were estimated in them in comparison to controls. Significant decrease in zinc and albumin levels were observed in liver cirrhosis patients. This work is an attempt to understand the important role that the zinc plays in the pathogenesis and therapy of liver cirrhosis and the role of albumin in zinc transport. Keywords cirrhosis of liver, zinc, albumin Introduction Cirrhosis is defined anatomically as a diffuse process of fibrosis and nodule formation due to different causes 1. Cirrhosis is elucidated histopathologically and has a variety of clinical manifestations and complications, some of which can be life threatening. Fibrosis and regenerative nodule formation result in a decrease of hepatocellular mass, function and alteration of blood flow. Induction of fibrosis occurs with activation of hepatic stellate cells, resulting in the formation of increased amount of collagen and other components of extracellular matrix 2. From 1934 to 1964, Cirrhosis of liver was a leading cause of death in United States. An increment in mortality was close to 60%.Yet epidemiologists have paid very little attention to this important and ever increasing cause of death 3. In India, several studies have shown that the two major causative factors of cirrhosis are viral hepatitis and alcohol abuse 4. Chronic hepatitis B (CHB) is an important global health problem, with more than 350 million individuals affected worldwide. Its prevalence in India is quite high. More than 1,000,000 Indian children run a lifetime risk of becoming chronic carriers and about 100,000 Indians die from HBV complications annually. During the course of hepatitis B virus (HBV) infection, an estimated 15-40% of CHB patients would develop complications such as acute exacerbation, liver cirrhosis and hepatocellular carcinoma (HCC) 5. It has been observed that Hepatitis B Virus (HBV) is the commonest cause of chronic liver disease in eastern India. Alcohol and Hepatitis C Virus (HCV) are uncommon in this part of the country 6. The study was carried out in the eastern part of India. Majority of the study population are not well nourished and may have micronutrient deficiency. Zinc is second to iron as the most abundant trace element in the body 7. Symptoms of acute zinc deficiency (anorexia, dysfunction of smell and taste and mental and Address for correspondence: Dr Kaushik Kar, CE 184, Salt Lake City, Sector 1, Kolkata kaushikkar37@yahoo.com

2 75 cerebellar disturbances) and chronic zinc deficiency (growth retardation, anemia, testicular atrophy and impaired wound healing) are common in cirrhosis patients. It remains unresolved whether these low serum zinc concentrations in these disease states are indicative of true symptomatic or asymptomatic zinc deficiency, or merely reflect a decrease in available zinc binding proteins, as well over 90% of serum zinc is bound to protein in normal subjects 8. Considering the fact, an attempt have been made to asses the zinc level in cirrhotic patients with an object to establish a correlation between zinc deficiency and manifestations of cirrhosis of liver. Albumin is the major plasma carrier of zinc, and the amount of zinc transported in the blood depends not on zinc but also on the availability of albumin 9. In this study, we tried to asses the serum zinc as well as serum albumin levels in liver cirrhosis patients. Table 1 and Fig. 1 showed significant fall in (s) zinc concentrations in liver cirrhosis patients, Table 2 and Fig. 2 showed significant fall in (s) albumin levels in liver cirrhosis patients. Fig. 1 Shows the serum zinc levels in controls and liver cirrhosis patients Materials and Methods The study was conducted in the department of Biochemistry, Calcutta National Medical College & Hospital, Kolkata, West Bengal. Liver cirrhosis patients were collected from outpatient department and wards of General Medicine department of the hospital.73 cirrhosis patients, 42 males and 31 females, age group of years as well as 35 normal control subjects (age and sex matched) were selected in the study. Diagnosis of cirrhosis was based on the Clinical, Laboratory and Radiological criteria. Cirrhosis associated with concomitant pathology like diabetes mellitus, hypertension and renal failure were excluded from the study. Severly ill,unconscious, disabled and non co-operative patients were also excluded from the study. Fasting blood was collected and serum was separated within optimum timing. Serum zinc and albumin was analysed immediately. (S) Zinc was estimated by colorimetric method. (Crest Biosystems) 10. (S) Albumin was estimated by Bromocresol green (BCG) dye binding method (Crest Biosystems) 11. Observations The results were tabulated and expressed as mean and standard deviation. The data were compared by SPSS software for significance. Discussion Biochemical alterations in cirrhosis : The transformation of normal liver to fibrotic liver and eventually cirrhosis is a complex process involving several

3 76 Fig. 2 Shows serum Albumin levels in controls and liver cirrhosis patients key components in particular stellate cells, cytokines, and proteinases and their inhibitors. There is interaction between stellate cells and adjacent sinusoidal and parenchymal cells, cytokines and growth factors, proteases and their inhibitors, and the extracellular matrix. The formation of fibrous tissue depends not only on the synthesis of excess matrix but also changes in its removal. This depends upon the balance between enzymes that degrades the matrix and their inhibitors. Normal liver has a connective tissue matrix which includes type IV collagen (non fibrillary), glycoproteins (including fibronectin and laminin) and proteoglycans (including heparin sulphate). These comprise the low density basement membrane in the space of Disse. Following hepatic injury there is a three to eightfold increase in the extracellular matrix, which is of a high density interstitial type, containing fibril-forming collagens (type I and III) as well as cellular fibronectin, hyaluranic acid and other matrix proteoglycans and glycoconjugates. There is a loss of endothelial cell fenestrations and hepatocyte microvilli, and capillarization of sinusoids, which impedes the metabolic exchange between blood and liver cells. The hepatic stellate cells (lies in the space of Disse) is the principle cell involved in fibrogenesis. In the resting state these cells have intracellular droplets containing vitamin A. Stellate cells are activated by factors released when adjacent cells are injured. Such factors include Transforming Growth Factor β1 (TGF-β1) from endothelial, Kupffer cells and platelets, lipid peroxides from hepatocytes, Platelet Derived Growth Factors (PDGF) and Epidermal Growth Factor (EGF) from platelets 12. Stellate cell activation is accompanied by loss of retinoid droplets, cellular proliferation and enlargement, and increased endoplasmic reticulum. The cells become contractile. They release cytokines, chemotactic factors, extracellular matrix and enzymes that degrade matrix 13. The increase in interstitial matrix is a further stimulus to stellate cell activation. Imbalance between matrix synthesis and degradation plays a major role in hepatic fibrogenesis 14. The degree of hepatic fibrosis following hepatocellular injury varies according to the cause and the balance between the response of stellate and Kupffer cells to the cytokines and growth factors that resolves with removal of the insult to severe scarring and nodule formation (cirrhosis) that is irreversible 15. Present study (Table 1 and Fig. 1) shows significant fall in serum Zinc concentrations in liver cirrhosis patients (p<0.001). Many of the clinical features of liver cirrhosis have been linked to zinc deficiency, including loss of body hair, testicular atrophy, poor apetite, immune dysfunction, altered taste and smell, reduced Vitamin A and thyroid hormone metabolism, altered protein metabolism, delayed wound healing and reduced drug elimination capacity. One of the most interesting and novel aspects is the role of zinc deficiency in producing liver cirrhosis is the possible relationship of zinc and hepatic encephalopathy (Mental and cerebellar disturbances) 16. Zinc is responsible for the activation of at least 200 metalloenzymes. There is a hypothesis that zinc ions present in the cytoplasm at mol/litre and in equilibrium with numerous zinc metalloenzymes and transcription factors can act as a master hormone particularly in relation to cell division and growth 7. Present study (Table 2 and Fig. 2) also shows significant fall of serum albumin(p<0.001) in liver cirrhosis patients. As the absorbed zinc is transported to the liver by portal circulation where active incorporation into metalloenzymes and plasma proteins such as albumin and α 2 macroglobulin occurs.

4 77 About 80% of plasma zinc is associated with albumin and rest is tightly bound to high molecular weight protein α 2 macroglobulin. The zinc on albumin is in eqillibrium with plasma amino acids. Zinc is loosely bound with albumin and tightly bound to α 2 macroglobulin. Albumin level is lowered in liver cirrhosis, zinc is mostly bound to α 2 macroglobulin and became unavailable 7. In this study, fall in serum albumin concentrations with simultaneous decrease in serum zinc concentrations were observed, and it can be proposed that low albumin level may be a cause of zinc deficiency in liver cirrhosis patients. Evaluation of zinc and albumin status may indicate the pathophysiological as well as therapeutic role of zinc and albumin in liver cirrhosis, so that long term supplementation of zinc and balanced protein diet to achieve nitrogen balance, may improve the neurological symptoms of cirrhosis of liver. Summary Cirrhosis of liver reflects irreversible chronic injury of the hepatic parenchyma and include extensive fibrosis in association with the formation of regenerative nodules. Since many of the clinical features of cirrhosis of liver simulates zinc deficiency, and major transporter of zinc in blood is albumin, (S) zinc and albumin levels were estimated in liver cirrhosis patients (n=73), in comparison to controls in our study. Significant decrease of (S) zinc and albumin levels were found in liver cirrhosis patients. From our study it can be hypothesized that some of the clinical features of liver cirrhosis may be contributed by zinc deficiency. Our study also indicates that zinc deficiency may be contributed by reduced (S) albumin level in liver cirrhosis patients. According to our study, measured zinc and protein supplementation in diet may improve some events of liver cirrhosis like testicular atrophy, immune dysfunction, reduced vitamin A and thyroid hormone levels, altered protein metabolism, delayed wound healing and hepatic encephalopathy. References 1. Sherlock S., Dooly J. Cirrhosis of liver, 11th ed. Diseases of the Liver and Billiary System: Blackwell Publishing, Oxford, , Bruce R., Bacon. Cirrhosis and its complications, 17th ed. Harrison s Principles Of Internal Medicine: McGraw-Hill, New York, , Terris M. Epidemiology of cirrhosis of liver; National mortality data. American J of Public Health. 57(12): 2076, Kumar T. Incidence of cirrhosis caused by hepatitis B virus in different sex and age groups in Bihar. Ind J of MGIMS. 11(1): 52-54, Misra B., Panda C., Das H.S., Nayak K.C., Singh S.P. Study on awareness about hepatitis B viral infection in coastal eastern India.Int J Hep B Annual. 6(1): 19-28, Ray G., Ghoshal U.C., Banerjee P.K., Pal B.B., Dhar K., Pal A.K., Biswas P.K. Aetiological spectrum of chronic liver disease in eastern India. Trop Gastroenterol. 21(2): 60-62, Shenkin A., Baines M., Fell G.S. et al. Vitamins and Trace elements, 4 th ed.teitz Textbook of Clinical Chemistry and Molecular Diagnostics: Elsevier, New Delhi, , Lindeman R.D., Baxter D.J., Yunice A.A., Kraikitpanitch S. Serum concentrations and urinary excretions of zinc in cirrhosis, nephritic syndrome and renal insufficiency. Am J Med Sci. 275(1):17-31, Gallagher M.L. The Nutrients and Their Metabolism. 12th ed.krause s Food & Nutrition Therapy: Saunders Elsevier, St. Louis, Missouri, 122, Akita Abe., Yamashita S. Determination of zinc in serum and urine. Clin. Chem. 35(4): , Doumas B.T., Watson W.A. Determination of Albumin in serum or plasma. Clin. Chem. Acta. 31:87, Li D., Friedman S.L. Liver fibrogenesis and the role of hepatic stellate cells: new insights and prospects

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