Urine Hemoglobin (Hemoglobinuria)

What sample is needed for Urine Hemoglobin (Hemoglobinuria)?

1. It can be done with fresh, random urine.
2. A morning sample is preferred.
3. Examine immediately.
4. If examined later, say for one hour, refrigerate the urine in the fridge to avoid microbial growth.
5. Mix urine well before testing the urine for Hb.

What are the indications for Urine Hemoglobin (Hemoglobinuria)?

1. To find the cause of hemoglobinuria due to various conditions:
   1. Hemolytic anemia.
   2. Other conditions are given below.

What are the precautions for Urine Hemoglobin (Hemoglobinuria)?

1. Examine immediately.
2. Can refrigerate if delayed.
3. Mix well before testing.

How will you define urine hemoglobin (hemoglobinuria)?

1. This is the presence of free hemoglobin in the urine, called hemoglobinuria.
2. When the level of free hemoglobin in the blood exceeds the renal excretion threshold, it results in hemoglobinuria.
3. This lysis of the RBCs takes place in dilute, alkaline urine.
4. The lysis of the RBCs in the urine usually shows a mixture of hemoglobinuria and hematuria.
5. Urine in hemoglobinuria and myoglobinuria is dark red or brown.
6. Hematuria:
   1. When RBCs are present in the urine, the condition is called Hematuria.
7. Myoglobinuria:
   1. The presence of myoglobin is called myoglobinuria. This is due to myoglobin, a muscle protein.
8. Hemoglobinuria:
   1. When hemoglobin is positive in the urine.

What are the causes of hemoglobinuria?

What is the mechanism of hemoglobinuria?

1. Erythrocyte lysis occurs at a specific gravity <1.010.
2. Hemoglobinuria may occur due to lysis of RBCs in the urinary tract.
3. Intravascular hemolysis leads to hemoglobinuria. In such cases, no RBCs are seen.
4. This will occur when the reticuloendothelial system can not handle or metabolize the hemoglobin by the hemolysis of RBCs (intravascular).
5. Under normal conditions, there is a complex of haptoglobin-hemoglobin, which the glomeruli will not filter.
6. When the hemoglobin exceeds the amount of haptoglobin in:
   1. Hemolytic anemias.
   2. Severe burns.
   3. Blood transfusion reactions.
   4. Strenuous exercise.
   5. Infections
7. The free hemoglobin can pass through the glomeruli.
8. The excess is absorbed in the proximal convoluted tubules.
9. The free hemoglobin can filter out and appear in the urine as hemoglobinuria.

10. This may also take place due to hemolysis in the urinary tract system.
11. Blood in the urine indicates damage to the kidneys or the urinary tract.

How will you differentiate between hemoglobinuria and myoglobinuria?

• You can differentiate between hemoglobinuria and myoglobinuria by the Ammonium sulfate precipitation test.

How will you detect hemoglobinuria?

1. The small amount of hemoglobin in urine does not give a visible color, which can be detected by the dipstick method.
2. O-toluidine test:
   1. It gives a blue color to hemoglobin.
   2. This also detects myoglobin.
   3. The false-positive test is seen in the following:
      1. If the container contains hypochlorite, an oxidizing agent.
   4. The false-negative test is seen in the following conditions:
      1. Vitamin C (ascorbic acid).
      2. Formaldehyde.
      3. Sensitivity is low when high specific gravity and a high nitrite concentration exist.
3. Benzidine test:
   1. It is not used because it is a carcinogenic agent.
   2. This test detects:
      1. RBCs.
      2. Hemoglobin.
      3. Myoglobin

Myoglobinuria:

1. In case of positive urine for occult blood but no RBCs are seen under the microscope, suspect myoglobinuria.
2. This occurs due to muscle injury, muscle disease disorder, and some poisoning.

What is the normal value of urine hemoglobin?

Source 1

• Normally, Hemoglobin is negative in the urine.
• <0.03 mg free Hb/dL.

What are the causes of Hemoglobinuria?

1. It is positive for all causes of hematuria, e.g
   1. Renal calculi.
   2. Tumors.
   3. Exposure to toxic drugs.
2. Intravascular hemolysis.
   1. Pregnancy and in puerpera.
   2. Transfusion reaction.
   3. Kidney infarction.
   4. Extensive burns.
   5. Paroxysmal nocturnal hemoglobinuria.
   6. Drugs and poison, e.g., sulfonamides, quinine, phenylhydrazine, poisonous snake, and fava beans.
   7. Infections, e.g., malaria, blackwater fever, gas gangrene, yellow fever, and anthrax.
   8. Direct trauma to RBC like exercise, heart valve prosthesis.
   9. Microangiopathic hemolytic anemia.
   10. Disseminated intravascular coagulopathy.
   11. Hemolysis in the donor blood due to improper storage.

How will you differentiate between Hematuria, Hemoglobinuria, and Myoglobinuria?

Questions and answers: