5 Common Calculated Parameters in Biochemistry Tests

1. AST/ALT

Aspartate Aminotransferase / Alanine Aminotransferase

Since ALT is present in the liver only in the cytosol of hepatocytes, while AST is present in 30% of the cytosol and the other 70% in the mitochondria. When hepatocytes are mildly diseased, only the enzyme in the hepatocyte plasma is released and the increase in ALT is greater than that of AST. Only when the damage is severe and the mitochondria are destroyed at the same time, the increase in AST exceeds that of ALT.

Clinical significance of the AST/ALT ratio

The AST/ALT ratio is different in patients with different types of hepatitis, for example

AST/ALT ratio < 1

When the hepatocytes are mildly diseased, the mitochondria of the hepatocytes remain intact, so the ALT is released into the blood mainly in the plasma of the hepatocytes; therefore, the increase of A LT is greater than that of AST, and the ratio of AST/ALT is < 1. For example, in the early stage of acute hepatitis and mild chronic hepatitis, the ratio of AST/ALT can be reduced to about 0.56. In the recovery phase of hepatitis, the ratio gradually increases to normal.

AST/ALT ratio ≈ 1

In severe hepatitis, moderate and severe chronic hepatitis, the mitochondria of hepatocytes are also severely damaged and AST is released from the mitochondria and cytoplasm, thus showing an AST/ALT ratio ≈ 1.

AST/ALT ratio > 1

When hepatocytes are severely damaged, enzymes in the cytosol and mitochondria are released, resulting in a greater increase in serum AST than ALT. For example, in cirrhosis, the ratio can be as high as 1.44, and in chronic active hepatitis, the ratio is often higher than normal.

AST/ALT ratio > 1, or even > 2

In patients with cirrhosis and hepatocellular carcinoma, the destruction of hepatocytes is more severe and the mitochondria are also severely damaged, so the AST is significantly increased and the AST/ALT ratio is >1 or even >2.

Patients with AST/ALT ratios of 1.20 to 2.26 often develop fulminant liver failure and die.

AST/ALT ratio > 3

It has been reported that 50% of patients with hepatocellular carcinoma have AST/ALT ratio > 3. The longer the disease duration, the higher the ratio, so AST/ALT ratio can also be used as one of the indicators to determine hepatocellular carcinoma. For long-term heavy drinkers, AST/ALT > 2 indicates the possibility of alcoholic liver disease, and AST/ALT > 3 has more diagnostic significance.

2. DBIL/TBIL

Direct bilirubin / total bilirubin

Jaundice can be divided into prehepatic jaundice (hemolytic jaundice), hepatocellular jaundice, and posthepatic jaundice (obstructive jaundice/cholestatic jaundice.) The DBIL/TBIL ratio is important in the differentiation of these three causes of jaundice.

Hemolytic jaundice, DBIL/TBIL ratio < 0.2. Hemolytic jaundice is due to hemolysis, excessive destruction of red blood cells and bilirubin production exceeding the load of the liver, mainly due to elevated indirect bilirubin, while direct bilirubin is essentially normal.

Hepatocellular jaundice, DBIL/TBIL ratio is 0.4 ~ 0.6. Hepatocellular jaundice is due to the impaired disposal of bilirubin by hepatocytes, which affects the uptake, binding and secretion of bilirubin by the liver, resulting in varying degrees of elevation of both direct and indirect bilirubin. Mostly mild to moderate jaundice, with DBIL/TBIL ratios between 0.4 and 0.6.

In obstructive jaundice, the DBIL/TBIL ratio is > 0.6. Obstructive jaundice is caused by the blockage of bile secretion and the reflux of bilirubin into the bloodstream, which is mostly moderate to severe jaundice, with a DBIL/TBIL ratio > 0.6. In the recovery period, the total bilirubin decreases and the DBIL/TBIL ratio may increase, even reaching 0.8 ~ 0.9. If the DBIL/TBIL ratio does not exceed 0.4, obstructive jaundice can be excluded.

3. A/G

Albumin / globulin

The ratio of albumin to globulin (A/G) mainly refers to the ratio of albumin to globulin, which is generally normal in the case of normal liver function, with albumin being higher than globulin.

Since the albumin in our body is made in the liver, when the liver function is abnormal, the albumin, which is the molecule in the albumin globule ratio, will be reduced and the phenomenon of low albumin globule ratio will occur.

Normal reference value: (1.5 to 2.5):1 (1); liver damage, mainly occurs in chronic processes, and the A/G ratio reflects the degree of liver function damage. A ratio of < 1.25 indicates liver damage. A ratio < 1 indicates severe lesions and is commonly associated with cirrhosis of the liver.

Multiple myeloma, lymphoma, systemic lupus erythematosus, rheumatoid arthritis and other diseases can cause a large amount of globulin synthesis, resulting in white ball inversion.

4. FPSA/TPSA

Free prostate-specific antigen / Total prostate-specific antigen

Currently, TPSA > 4 ug/L is usually used as the threshold value for screening prostate cancer in China. TPSA results between 4 and 10 ug/L are referred to as the gray area, where both prostate cancer and prostate hyperplasia are possible. In contrast, when TPSA > 10 ug/L, prostate cancer is highly likely.

The higher the FPSA, the better. The FPSA/TPSA ratio of 0.19 is often used as the threshold value. FPSA/TPSA is important when the serum TPSA is in the gray area, and when FPSA/TPSA > 0.19, prostate cancer is less likely. When the FPSA/TPSA value is < 0.19, prostate cancer is more likely. when the TPSA is in the normal range, the FPSA/TPSA ratio is negligible.

5. PGI/PGII

Pepsinogen I / Pepsinogen II

The combined PGI and PGII ratios can serve as a "serological biopsy" of the fundic gland mucosa. Common meanings are as follows.

• PGI ≥ 70 ng/mL or PGI/PGII negative (-) Normal
• PGI < 70 ng/mL and PGI/PGII positive (+) Mild atrophy
• PGI < 50 ng/mL and moderately positive PGI/PGII (2+) Moderate atrophy
• PGI < 30 ng/mL and strong PGI/PGI I positive (3+) Highly atrophic

Analysis of the prognostic dynamics of gastric diseases by PG test: PGI > 240 or PGII > 240

If PGI > 240 or PGII > 20, there is a break in the gastric mucosa and it is recommended to have a gastroscopy for further examination or a review after two weeks of abstinence from alcohol. Possible reason is that PGII is more stable, but PGI in active phase will increase significantly when gastric mucosa is attacked or damaged. HP infection, superficial gastritis, erosive gastritis, gastric ulcer, duodenal ulcer, can lead to increase of serum PGⅠ and PGⅡ. The recurrence of gastric ulcer has a significant increase in PGII, and the recurrence of duodenal ulcer has a significant increase in PGⅠ and PGⅡ.

PGI < 70, PGI/PGII < 3 when PGI/PGII < 3 gastric mucosal cell atrophy, gastroscopy is recommended for further examination, with predominantly atrophic gastritis, with special attention to high risk factors for atrophic gastritis, intestinal chemosis, heterogeneous hyperplasia, gastric cancer, etc.

PGI < 70, PGI/PGII > 3 low pepsinogen secretion, regular review is recommended, with low gastric acid secretion predominant and high risk of atrophic gastritis, intestinal metaplasia, etc.

These are the 5calculated parameters commonly found in biochemical tests.