Content:
◉ Introduction
Hemoglobin is a molecule found in the red blood cells and it helps carry oxygen and transport it to the various tissues of the body, and take carbon dioxide back to the lung.
As the life span of the red blood cells ends 3 months later, they break down in the liver, spleen and bone marrow into parts for the turnover and production of new red blood cells.
If red blood cells break down inside the lumen of the blood vessels, their components leave the blood stream through the kidneys into the urine, known as hemoglobinuria. Sometimes whole red blood cells are present in the urine. This is known as hematuria.
◉ What is Hemoglobinuria
Hemoglobinuria refers to the presence of free hemoglobin in the urine. This condition occurs when red blood cells break down rapidly, and the liver may not have sufficient time to process and detoxify the released hemoglobin. As a result, the hemoglobin passes through the kidneys and into the urine, causing a characteristic change in urine color to reddish-brown.
◉ Urine Appearance
In cases of hemoglobinuria, the appearance of urine differs from normal. A typical urine sample is pale yellow and clear, without any visible sedimentation or particles. Occasionally, it may appear more concentrated, especially in dehydrated individuals, but remains within the normal range. However, a dramatic change in color indicates an underlying issue.
In hemoglobinuria, urine takes on a reddish or brownish hue due to the presence of hemoglobin pigment. Additionally, it may exhibit turbidity due to the presence of other particles and cells. Hemoglobin passing through the kidneys often causes injury, resulting in the presence of proteins and epithelial cells in the urine. This contributes to its abnormal appearance and consistency and may increase its specific gravity.
Moreover, as hemoglobin is a basic protein, an increase in urine pH creates a more favorable environment for bacterial growth and infection, further complicating urine analysis results.
◉ Causes of hemoglobinuria
Hemoglobinuria occurs after severe intravascular hemolysis in which a large number of red blood cells are destroyed, this condition can be caused by :
- Acute kidney injury (AKI): hemoglobinuric AKI occurs by multiple mechanisms as aciduria, dehydration and renal ischemia all of these are factors in pathological processes. All of these conditions are thought to enhance heme toxicity and causing hemoglobinuria.
- Burns: after burn for a few hours destruction of red blood cells reach 30-46% and patients will have abrupt hemolysis that hemoglobinuria is one of its manifestations.
- Renal cell carcinoma.
- Malaria: severe intravascular hemolysis of erythrocytes in severe falciparum malaria which results in hemoglobinuria.
- Paroxysmal nocturnal hemoglobinuria: this is an intravascular hemolysis that occurs due to immunological reaction through the complement system activation.
- Hemolytic uremic syndrome: this is a blood disorder which is characterised by acute kidney injury resulting in hemoglobinuria.
- Thrombotic thrombocytopenic purpura: This is a blood disorder characterised by formation of blood clots as a result of clot formation The patient will have low platelet count and low red blood cells due to their breakdown. The patient will have a headache, peteiche, jaundice and hemoglobinuria.
- G6PD deficiency : this is also called favism this is an inborn x-linked recessive disorder which causes hemolytic anaemia in person when eating fava beans and having infection. Patients will have prolonged neonatal jaundice, hemolytic crisis and hemoglobinuria.
- Sickle cell disease (SCD): this is an inherited blood disorder in which patients have sickle shaped blood cells this patient develops hemolytic anaemia and hemoglobinuria one of its symptoms.
- March hemoglobinuria: this is a disease characterised by transient hemoglobinuria which happens after straneous exercise such as marathon and kendo.
- Poisoning: snake and insect envenomation lead to severe intravascular hemolysis.
- Haemorrhagic fevers.
- Septic shock.
◉ What to do with hemoglobinuria
When faced with hemoglobinuria, it is crucial to recognize that it is a symptom that can be caused by various medical conditions, such as AKI, burns, infections, hematological disorders, etc. To effectively identify the cause, a thorough evaluation is necessary. This includes:
1- Obtaining the patient's medical history to search for any recent events that may be related to the onset of hemoglobinuria.
2- Examination of associated symptoms and clinical signs.
3- Laboratory tests are also essential, including:
- Urine analysis to confirm the presence of hemoglobin and search for other abnormalities.
- Blood tests to evaluate levels of hemoglobin, creatinine, bilirubin, and other relevant markers, as well as other specific tests based on the diagnostic hypothesis.
Once the cause is identified, treatment can be tailored accordingly to address the underlying medical condition and prevent complications associated with hemoglobinuria.
◉ Conclusion
Hemoglobinuria is a symptom that manifests in many diseases and disorders. It means red blood cells are being very rapidly destroyed in the blood vessels and releasing their contents in the lumen to be excreted through the urine, which may cause acute injury to the kidneys. Hemoglobinuria changes the appearance, consistency and contents of the urine sample and is indicative of a serious underlying disease and further investigations must be carried out for proper and early management.