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Wednesday, May 27, 2015

Pediatric Liver function test : smarter way

This post is basically to get rid of my own confusions on liver function test for smarter interpretation in sick children and Should anybody, comes across this and find it useful then all the better!

Part One: Tests that detect injury to hepatocytes (serum enzyme tests)

1. ALT/SGPT

Primarily marker of hepatocellular injury (most sensitive, more specific than AST),
Liver cell death —> leaks in blood.
No correlation with extent of damage.

A) High ALT (>15-20 times)

          Ischaemia (Much Higher) (Shock, hypotension, CCF, comes down rapidly)
          Viral hepatitis, Autoimmune
          Drug toxicity (PCM), Severe toxic hepatitis
          Acute budd chiary syndrome

B) Moderate ALT (5-15 times)

          Liver – Chronic Liver disease (eg Chronic hepatitis)
          Cholestasis (with ALP, GGT)
          Cardiac –Severe hepatic congestion in cardiac failure
          Other: Muscle injury, Kidney injury

C) Slight increase in ALT (<5 times)

          Liver: Neonatal hepatitis
                    Hemochromatosis
                    Autoimmune hepatitis
                    NASH, EHBA
                    Alpha1-antitrypsin deficiency, Wilson’s disease
          Infection: Infectious mononucleosis
          Drugs: Almost any drug. (ATT, AED, Antibiotics, NASAIDS), PCM therapeutic doses,

D) False low ALT: Dialysis, Pyridoxine deficiency
Note: Drugs more likely to cause an asymptomatic abnormality in liver function.
 
2) AST/SGOT

Origin: Liver, cardiac, skeletal muscle, kidney, brain, pancreas.
Reflects damage to the hepatic cell , but less specific for liver disease.

A) High AST (>20 times)
            Ischaemic liver injury(Shock, hypoperfusion)
            Acute viral hepatitis
            Drug induced hepatic injury
B) Moderate AST (15-20 times)
            CVS: (CCF)
            Infection: (Infectious mononucleosis)
            Liver: (Alcoholic cirrhosis)
C) Mild AST (5-10 times)
            Liver: Chronic hepatitis Specially alcoholic
            Skeletal muscle: DMD, Dermatomyositis, Infl. B calf muscle myositis
D) Even milder AST (<5 times)
            Blood: Haemolytic anaemia, haemolysis
            Liver; Fatty liver, Metastatic hepatic tumour
            Other: PE, Acute pancreatitis, Strenuous exercise
            Drugs: Almost any drug
 
Ratios between AST and ALT are useful in differentials 

AST: ALT =1 (Equal rise)
           Ischaemia ( Shock, hypoxia, hypoperfsion injury)
AST: ALT <1 ( More ALT, specific for Hepatocellular damage )
           PCM poisoning with hepatocellular necrosis
           Viral hepatitis, toxic hepatitis, Cholestatic hepatitis
           Chronic active hepatitis, NASH
AST: ALT >2.5 (More AST)
          CLD, cirrhosis
          Wilsons disease, cirrhosis
          Bile duct obstruction, Tumours
          (Adults:Alcoholic liver disease)

WHY: Depletion of vitamin B6 in chronic alcoholics. ALT and AST both use B6 as a coenzyme, but the synthesis of ALT is more strongly inhibited by pyridoxine deficiency than is the synthesis of AST. Alcohol also causes mitochondrial injury, which releases the mitochondrial isoenzyme of AST.

Asymptomatic Transaminitis
Slight AST or ALT elevations (within 1.5 × normal) do not necessarily indicate liver disease.

WHY: unlike the values in many other biochemical tests, AST and ALT levels do not follow a normal bellshaped distribution in the population.
They have a skewed distribution characterized by a long “tail” at the high end of the scale.

3. Alkaline Phosphatase (ALP)

Thursday, March 12, 2015

Capnography supersimplified:Basic Interpretaion

“ It is always usefull to start by asking: Is there any EtCO2? Is it normal or abnormal? and what is the trend? ”
John H. Eichhorn. University of Mississippi school of medicine/Medical centre, Jackson, Mississippi.

Second short post on simplified capnography focusing on how to simply understand abnormal capnograph. This is more theoretical post, it will be followed by graphical post on how to make specific interpretation in cardiac arrest, mechanical ventilation, sedation and other scenarios.

Never forget:
Most frequent abnormal capnograms results from technical problems like improper calibration, loose connection, cracks in connector of circuits specially in side stream capnography. These need to be ruled out before hand in case of sudden changes in trend and no correlation clinically or in relation with blood gases.

Picture5
CHECKLIST FOR INTERPR- ETATION


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