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Showing posts with label hepatology. Show all posts
Showing posts with label hepatology. Show all posts

Functions of liver and different liver function tests

Major functions of Liver are the following

  1. Blood glucose regulation
  2. Synthesis of glycogen
  3. Synthesis of triacyl glycerol
  4. Synthesis of plasma proteins
  5. Detoxification
  6. Bile production, helps in digestion
  7. Bilirubin metabolism

Biochemical test are done to assess the following
The hepatic function 
To detect hepatic injury
Patterns of abnormalities are more important than single test
May be normal in proven liver disease
Normal value never rules out liver Disease

Classification of liver function test based on laboratory findings
Hepatic excretory function is assessed with following tests
Serum Bilirubin
Urine: Bile Pigments, bile salt, urobilinogen
Liver enzymes
ALT,AST,ALP,GGT,5’ nucleotidase

Synthetic Function
Total Proteins
Serum albumin, globulins
Prothrombin time

Special Test
Alpha1 antitrypsin
Alpha fetoProteins
Classification of liver function  based on clinical aspects
Markers of liver dysfunction
Serum Bilirubin
Urine: Bile pigments, bile salt, urobilinogen
Total proteins, albumin
Prothrombin time
Blood ammonia

Markers of hepato cellular Injury
Markers of cholestasis
5’ Nucleotidase 

What is nonalcoholic fatty liver disease and what are its risk factors?

Definition of NAFLD 
This is a condition where patients having hepatic steatosis with or without inflammation and fibrosis, without any secondary causes of hepatic steatosis.

Following are the criteria for diagnosing nonalcoholic fatty liver disease
Imaging or biopsy should demonstrate  hepatic steatosis. 
Significant alcohol consumption  should be excluded.
Other causes of hepatic steatosis  should be  excluded.

What are the stages of NAFLD?
It include progression from steatosis, steatohepatitis to cirrhosis of liver
Steatosis ( Fatty liver )– NAFLD
Steatohepatitis – NASH

What are the disorders associated  with  NAFLD
Systemic Hypertension
Insulin resistance or overt diabetes
Hypopituitarism and hypogonadism
A family history of steatohepatitis or cryptogenic cirrhosis is  also implicated as a risk factor

Prevalence  of NAFLD
It is seen in 10-24% of general population.
2.6% of pediatric population have NAFLD.
It is the most common cause of cryptogenic cirrhosis
2/3rd of the obese patients have NASH.
90% of  morbidly obese patients have NASH.

Pathophysiology of ascites in Cirrhosis

There are numerous causes of ascites, the most common causes are
1. Malignant disease.
2. Cirrhosis.
3. Heart failure. 

Primary disorders of the peritoneum and visceral organs can cause ascites, and they should be considered even in those patients with chronic liver disease (CLD).
The main cause of ascites in cirrhosis is Splanchnic vasodilatation.It is mediated by vasodilators especially nitric oxide.These vasodilators are released when there is shunting of blood into the systemic circulation due to portal hypertension.As cirrhosis advances systemic arterial pressure falls due to severe splanchnic vasodilatation. 

This in turn leads to 
1. Activation of the RAS (renin–angiotensin system) with secondary aldosteronism.
2. Increased sympathetic nervous system activity.
3. Increased atrial natriuretic hormone secretion.
4. Altered activity of the kallikrein–kinin system.

These systems will try to normalise the arterial pressure but they result in salt and water retention.Combination of splanchnic arterial vasodilatation and portal hypertension tend to alter the intestinal capillary permeability, resulting in accumulation of fluid within the peritoneal cavity.