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Sample

Precautions

  1. Try to separate serum or plasma from the cells within 2 hours.
  2. Best sample is after 12 to 14 hours of fast.
  3. Pregnancy may give a high level.
  4. Drugs that may increase the level are anabolic steroids, corticosteroids, oral contraceptives, vitamin D, phenytoin, thiazide diuretics, and cyclosporin.
  5. Drugs that may decrease the level are captopril, colchicine, erythromycin, isoniazid (INH), lovastatin, neomycin, bile salt binding agents, androgens, niacin, and nitrates. 

Purpose of the test

Pathophysiology

  1. Cholesterol is absorbed in the diet and synthesized in the liver and gut. It is a precursor of steroid hormone and bile acids.
  2. Cholesterol is present in the diet, mostly comes from the animal source and absorbed by the GItract.
    1. Another source is endogenous like liver and other tissues. 
      1. All the cells have the ability to synthesize the cholesterol and 90% occurs in the liver and intestines.
    2. Malnutrition will give low cholesterol formation.

  1. Cholesterol absorption:
    1. The cholesterol enters the intestine from following sources:
      1. Food like egg yolk, meat, fat-diary products, and seafood, the average amount is 400 to 700 mg/day.
        1. Plant sterols (200 to 300 mg ) are ingested daily. These are poorly absorbed.
      2. Bile, provide another fraction of cholesterol.
      3. Intestinal secretions and turn over of the intestinal mucosal cells are another source.
      4. Bile acids are detergents and are the most important factor affecting micelles formation.
        1. In the absence of bile acids, digestion and absorption of the cholesterol and triglyceride are severely affected.
      5. Most absorption of the cholesterol takes place in the jejunum and ileum.
      6. When cholesterol enters the intestinal cells then it is packaged with triglycerides, phospholipids, apolipoprotein into large lipoprotein called chylomicrons.
      7. When there is an increased amount of fat in diet particularly triglycerides 98%, will result in more micelles formation which in turn allows more cholesterol to be solubilized and absorbed.


  1. Cholesterol once formed is enter the blood circulation.
    1. It is then esterified and combine with apoprotein and apolipoprotein and ultimately carried as a lipoprotein.

  1. Biosynthesis of Cholesterol 
    1. Cholesterol synthesis takes place in three stages.
    2. The starting molecule is acetate.
    3. All body cells have the ability to synthesize cholesterol from Acetyl Co A, but 90% it takes place in the liver.

  1. Cholesterol exists in two forms:
    1. Free cholesterol.
    2. Esterified cholesterol. 
      1. 75 to 85% of the total cholesterol is in form of esterified cholesterol.
        1. Cholesterol can be derived from a dietary source like meat, eggs, butter, and plants.
        2. 30 to 60% of the dietary cholesterol is absorbed.
        3. Once cholesterol is absorbed into the mucosal cells then it becomes part of the large micelle is called Chylomicron.

    1. Cholesterol is blood lipid ( fat ).
    2. Cholesterol is a normal part of RBC.
    3. Cholesterol, when increased, leads to atherosclerosis and is the main lipid.

    1. Cholesterol is the basic unit of hormone produced by adrenal glands, ovaries, and testes.
    2. cholesterol is needed for bile acids and cellular membranes.
    3. Cholesterol is transported in the circulation by carrier proteins.
      1. Cholesterol bound to high-density lipoprotein (HDL- cholesterol) is known as good cholesterol. This will prevent atherosclerosis.
      2. Cholesterol bound to low-density protein (LDL-cholesterol) is known as bad cholesterol and increases the chances of atherosclerosis.
      3. Also the same is the cholesterol bound to very low-density lipoprotein (VLDL) is bad cholesterol.
    4. Increased Cholesterol level is associated with atherosclerosis and coronary vessels disease.

Normal

Source 1
Adult
  1. The desired level to prevent coronary disease is < 200 mg/dl
  2. Moderate risk is 200-239 mg/dl
  3. High risk is > 240 mg/dl
  4. CSF <0.5 mg/dl

Source 2

Sample Male mg /dL  Female mg /dL
Cord blood 44 to 103 50 to 108
0 to 4 years 114 to 203 112 to 200
5 to 9 years 121 to 203 126 to 205
10 to 14 years 119 to 202 124 to 201
20 to 24 years 124 to 218 122 to 216
30 to 34 years 138 to 254 130 to 230
40 to 44 years 151 to 268 147 to 252
50 to 54 years 158 to 277 162 to 285
60 to 64 years 159 to 276 172 to 297
>70 years 144 to 265 173 to 280

Children

  1. Desirable level is < 170 mg/dl
  2. Moderate risk is 170-199 mg/dl
  3. High risk is > 200 mg/dl

Above 240 mg/dL     needs treatment.

Now a days cardiology association recommend the level to be around 160 mg/dl.

  1. level < 160 mg /dl    very low risk
  2. level 160—199 mg/dl     low risk
  3. level 200—239 mg/dl     moderate risk
  4. level 240—279 mg/dl     high risk
  5. level > 280 mg/dl     very high risk

ATP III (Adult treatment panel) recommendations are:

Total Cholesterol 

  1. Desirable level = <200 mg/dL
  2. Borderline level = 200 to 239 mg/dL
  3. High Risk level = >240 mg/dL

Increased Cholesterol (Hypercholesterolemia):

  1. Familial combined hyperlipidemia.
  2. Hyperlipoproteinemia type, 1V, V.
  3. Intra- and extrahepatic cholestasis.
  4. Glomerulonephritis.
  5. Nephrotic syndrome, and chronic renal failure.
  6. Malignant neoplasm of pancreas and prostate.
  7. Hypothyroidism.
  8. Gout.
  9. Diabetes mellitus.
  10. Alcoholism.
  11. Glycogen storage diseases type 1 (Von Gierke disease).
  12. Stress.
  13. biliary cirrhosis.

Decrease Cholesterol (Hypocholesterolemia):

  1. alpha-Lipoprotein deficiency.
  2. Hepatocellular necrosis.
  3. Malignant neoplasm of the liver.
  4. Hyperthyroidism.
  5. Malabsorption and malnutrition.
  6. Severe acute illness.
  7. Extensive burns.
  8. Rheumatoid arthritis.
  9. Cholesterol-lowering medications.

Prevention and Interpretation:

Total cholesterol <200 mg/dL Check after 5 years
Total cholesterol 200 to 239 mg/dL 0 to 1 risk factor and no coronary disease. Needs diet control and repeat test after one year.
Total cholesterol >240 mg/dL Diet control and/or drugs intervention

Risk factors are:

  1. Cigarette smoking.
  2. Cerebrovascular disease.
  3. Diabetes mellitus.
  4. Hypertension.
  5. The family history of coronary heart disease.
  6. Sex as in male.
  7. Overweight >30%
  8. peripheral occlusive vascular disease.

Important

      • There is variation in the level of cholesterol so take at least two sample.

 


Possible References Used

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