Others

NORMAL BUN and Urea

Source 2

• Urea
  •  20 to 40 mg/dl
• BUN
  • Blood urea nitrogen (BUN) = 10 to 20 mg /dl
  • Children (BUN) = 5 to 18 mg/dl
  • Infants = 5 to 18 mg/dL
  • Newborn = 3 to 12 mg/dL
  • Cord blood = 21 to 40 mg/dL
  • Older people may have a higher level than adults.

Indications For Blood Urea Nitrogen (BUN)

1. To assess renal function.
2. As a routine test in the patient with dialysis.
3. To assess liver function.
4. This may be part of the routine test.
5. In patients:
   1. Has nonspecific symptoms.
   2. During the hospital stay.
   3. Before some drug therapy.
   4. Acutely ill patients are admitted in an emergency.
6. BUN is a less specific indicator of the kidney’s function and is not reliable.

Common causes of uremia: increase BUN

Decreased Urea/BUN seen in:

1. Severe liver diseases (liver failure).
2. Malnutrition and a low protein diet.
3. Impaired absorption of Celiac disease.
4. Syndrome of inappropriate antidiuretic hormone secretion.
5. Increased utilization of protein for synthesis:
   1. Late pregnancy.
   2. Acromegaly.
   3. Infants.
   4. Anabolic hormones.
   5. Malnutrition.
6. Overhydration.
7. Nephrotic syndrome.

1. Pre-renal factors for raised serum creatinine are:
   1. Congestive heart failure.
   2. Shock.
   3. Salt and water depletion due to:
      1. Vomiting.
      2. Diarrhea.
      3. GIT fistulas.
      4. Increased use of diuretics.
      5. Uncontrolled diabetes mellitus.
      6. Diabetes insipidus.
      7. Excessive sweating (decreased salt intake).
2. Renal factors for raised serum creatinine are:
   1. Damage to:
      1. Glomerulus.
      2. Tubules.
      3. Interstitial tissue.
      4. Blood vessels.
3. Post-renal factors for raised serum creatinine are:
   1. Benign prostatic hyperplasia.
   2. Neoplasia compresses the ureter.
   3. Calculi obstructing the ureter.
   4. Congenital abnormalities obstruct or compress the ureter.
   5. 
      

The decreased creatinine level is seen in the following conditions:

1. Old-age.
2. Decreased muscle mass.
3. Pregnancy, especially in the first and second trimesters.
4. Advanced and severe liver disease.
5. Inadequate dietary intake.

Drugs leading to an increased level of creatinine:

1. Gentamicin.
2. Cimetidine.
3. Heavy metals chemotherapy, e.g., Cisplatin.
4. Nephrotoxic drugs like Cephalosporin, e.g., Cefoxitin.

Normal

• 1 to 17 U/hour
• 170 to 2000 U/L

Increase Urine Amylase Level Seen In:

1. Acute Pancreatitis.
2. Chronic relapsing pancreatitis.
3. Penetrating peptic ulcer to the pancreas.
4. Acute cholecystitis.
5. Parotitis (mumps), called sialadenitis.
6. Ruptured ectopic pregnancy.
7. Pulmonary infarction.
8. Autoimmune diseases.
9. Pancreatic cyst.
10. Peritonitis.
11. Biliary tract disease.
12. Diabetic ketoacidosis.
13. Intestinal obstruction.
14. Few lung or ovarian tumors.

Decreased Urine Amylase Is Seen In:

1. Pancreatic Insufficiency.
2. Renal failure.
3. Liver disease (severe).
4. Advanced cystic fibrosis.

Amylase/Creatinine Clearance Ratio Is Increased In:

1. Pancreatitis.
2. Toxemia of pregnancy.
3. Diabetic ketoacidosis.
4. Renal insufficiency

Increased Values Of Creatinine Clearance:

1. This has no clinical significance; we suspect some errors in the collection procedure.
   1. Pregnancy
   2. Exercise.
   3. High cardiac output syndrome.

Decreased Values Of Creatinine Clearance (CrC):

1. It is a very sensitive indicator of decreased glomerular filtration rate when done with all precautions.
   1. Diseases of the kidney with impaired renal function.
   2. Congestive heart failure.
   3. Cirrhosis with ascites.
   4. Shock.
   5. Dehydration (loss of body fluids).
   6. Bladder outlet obstruction.