Generality
The presence of hemoglobin in the urine, defined by the medical term hemoglobinuria, can be the consequence of hemolysis (rupture) of the red blood cells at intravascular level (in the blood vessels) or intravesical (in the urinary bladder).
Ultimately, therefore, hemoglobinuria does not necessarily reflect a loss of blood with the urine, but only of blood pigments (hemoglobin) that color them red.
Hematuria is often accompanied by hemoglobinuria, caused by the haemolysis of red blood cells contained in urine, while hemoglobinuria can be separated from hematuria, because it is often supported by the already mentioned phenomena of excessive intravascular hemolysis.
Another important clarification is that the excretion of reddish urine is not necessarily synonymous with hematuria or hemoglobinuria; in fact, a urine of this color may simply be due to contamination with menstrual flow or to the intake of particular foods or drugs.
According to the above, the presence of hemoglobin in the urine gives them a homogeneous red-brown color. Among the various symptoms that can be associated with hemoglobinuria, in relation to the cause of origin, we recall fever, chills, enlargement of the spleen (splenomegaly), skin pallor, tachycardia, shortness of breath, weakness and jaundice.
What's this
Hemoglobinuria occurs when the presence of hemoglobin (Hb) is found in the urine.
This condition typically occurs when the level of Hb in the blood reaches values that are too high, following a sudden and massive destruction of red blood cells ( hemolysis ).
If the hemoglobin concentrations in the blood are high, the functions of the reticulo-endothelial system cells - which recover the circulating free hemoglobin, transforming it into bilirubin to dispose of it - could fail or act in a not completely sufficient manner.
A few notes on hemoglobin
Hemoglobin is the essential component of red blood cells (to which it also gives color). Its function is to transport oxygen from the lungs to tissues in the periphery.
When red blood cells die from physiological or pathological causes (hemolysis), they release the hemoglobin they contain into the blood, which is immediately picked up by the haptoglobin .
The complex obtained is too large to be filtered by the renal glomeruli, therefore it is processed and degraded by the recycling of iron, by the immune cells that make up the reticular-endothelial system. However, if the quantity of hemoglobin released into the blood exceeds 3 grams, the complete saturation of the circulating haptoglobin occurs (this protein has a concentration ranging from 50 to 150 milligrams per deciliter of blood). In such circumstances, free hemoglobin, from compound to 4 peptide chains, splits into compounds with two peptide chains and as such manages to cross the renal barrier.
At this point, the epithelial cells of the proximal renal tubule process the filtered hemoglobin, transforming it into ferritin and hemosiderin . If the quantities of hemoglobin are considerable and the absorption capacity of the renal tubules is exceeded, then there is a passage of hemoglobin in the urine (hemoglobinuria).
Why do you measure
Hemoglobinuria can occur in all situations that lead to sudden and increased destruction of red blood cells, and to their elimination with urine.
Most of the time, the presence of hemoglobin in the urine is the indicator of some pathologies affecting the urinary tract.
The first step to ascertain the exact triggering causes of hemoglobinuria is urinalysis and urine culture.
With the help of the medical history analysis and the ascertainment of the clinical picture (possible symptoms and signs present simultaneously with the hemoglobinuria), the doctor will direct the patient towards targeted clinical investigations, based on the suspected diagnosis.
Normal values
When talking about hemoglobin in the urine there is no real reference value that indicates normality, as this should not be present in the urine of a healthy person.
- Normal value: absent.
Hemoglobin in the urine High
The presence of hemoglobin in the urine is mainly determined by anemia characterized by:
- Defective production of red blood cells;
- Too high a rate of their destruction.
In both cases, hemoglobin is released into the bloodstream and, when this presence becomes excessive and its natural disposal becomes difficult, it is eliminated in the urine.
The conditions in which hemoglobinuria most commonly occurs are:
- Poisonings;
- Reactions to incompatible blood transfusions;
- Extensive burns;
- Use of certain drugs (eg penicillin, cephalosporins or antiarrhythmic drugs, such as quinidine, may cause intravascular hemolysis and passage of hemoglobin in the urine);
- Malaria;
- Some acute infections;
- Food poisoning.
There is also a series of diseases that can cause hemoglobinuria. Favism is, for example, a genetic disease characterized by the deficiency of the enzyme glucose-6-phosphate dehydrogenase. If the patient takes substances such as the divicina contained in the broad beans or some drugs, this deficiency determines the rupture of the red blood cells with the circulation in the hemoglobin, which will then be filtered by the kidneys and will fall into the urine.
Furthermore, among the possible conditions associated with the presence of hemoglobinuria it should be remembered:
- Acute glomerulonephritis (acute inflammation of the renal glomeruli);
- Urinary tract tumors;
- Sickle cell anemia;
- Cooley's disease;
- Hemolytic-uremic syndrome;
- Malfunction of heart valve prosthesis;
- Lead exposure;
- Renal calculosis;
- Chronic renal failure;
- Renal carcinoma;
- Disseminated intravascular coagulation (CID);
- Thrombotic thrombocytopenic purpura;
- Tuberculosis of the urinary tract.
Hemoglobinuria in pregnancy
In pregnancy, it may be normal to find traces of hemoglobin, as well as blood in the urine, which may depend on cystitis.
However, if the values increase considerably it could be a symptom of gestosis.
Hemoglobin in the urine in clinical syndromes
In other cases, hemoglobin appears periodically in the urine, in the framework of clinical syndromes such as:
- Exercise or travel hemoglobinuria : occurs due to unknown causes after intense and prolonged physical exertion, exercised in an upright position. Prepared to develop this condition are the athletes who practice the march and the race, and those who work for a prolonged period, facing demanding physical activities (eg use of a jackhammer). Exercise or walking hemoglobinuria may appear above all if these activities take place in a condition of dehydration. However, this condition has a benign character and the phenomenon tends to disappear spontaneously.
- Paroxysmal cold hemoglobinuria: the hemoglobinuric crisis occurs following exposure of the body, or part of it, to low temperatures. This condition is often related to a luetic infection, but may be idiopathic or dependent on other viral and bacterial infections.
Paroxysmal cold hemoglobinuria is due to the presence in the plasma of a particular substance, hemolysin, which at low temperatures binds with red blood cells and exerts its hemolytic activity at 37 ° C.
- Paroxysmal nocturnal hemoglobinuria : a genetic disease so called due to the fact that it is closely linked to sleep, so that the urine emitted in the morning is dark upon awakening due to the presence of hemoglobin. The condition is associated with an acquired defect of red blood cells, which makes them more susceptible to different factors (such as probably the modification of the pH of the blood that occurs during sleep).
The disease begins insidiously, mostly in young subjects, and can be aggravated by infections, blood transfusions, surgery and different types of drugs. The evolution is chronic and slow, and the severity of the manifestations differs from case to case.
Possible associated symptoms
In the presence of hemoglobinuria, the urine has a color ranging from amaranth to brown, in relation to the proportional concentration of two pigments: oxyhemoglobin (bright red) and methaemoglobin (red-brown).
This phenomenon can be accompanied or not by a series of other symptoms, which will be related to the pathology that triggers hemoglobinuria, such as:
- Headache;
- General malaise;
- Sense of prostration;
- Temperature;
- Chills;
- Skin pallor;
- Enlarged spleen (splenomegaly);
- Tachycardia;
- Short or difficult breath;
- Pains in the abdomen and lower limbs.
The hemoglobin that passes through the kidney can precipitate in the renal tubules, causing serious alterations that sometimes result in renal blockage and uremia.
Low hemoglobin
As a rule, hemoglobin is not present in the urine.
For this reason, even a low concentration must lead to further investigations. Finding a reddish urine, however, should not immediately create an alarm, as it may depend on taking some medicines or certain foods.
How to measure it
The presence of hemoglobin should be investigated by cytological examination of urine. In practice, a microscopic examination of the cells emitted with the urine is performed, after having carried out a particular procedure that is called "panoptic coloring".
Preparation
For the evaluation of hemoglobin in the urine it is necessary to collect a small amount of urine in the morning, on an empty stomach, after having carried out a thorough intimate hygiene and after letting go of the very first emission (which may contain the germs present on the outside of the urinary tract).
In the case of women, it is good to take the exam away from the menstrual period.
The urine must be collected in a sterile container, which must be carefully closed immediately afterwards and taken to the laboratory within a short period of time.
Interpretation of Results
In the presence of hemoglobinuria, it is always good to consult your doctor, so as to identify the cause and prepare for treatment.
Causes of hemoglobin in the urine
The detection of hemoglobin in the urine, absent in normal conditions, is the typical consequence of hemolytic processes (destruction of red blood cells), which release into circulation the hemoglobin contained in the injured red blood cells.
When the concentrations of this pigment reach particularly high levels - such as to saturate the haptoglobin, the systems of recovery and disposal of the endothelial reticulum system, and the capacity for reabsorption of the proximal tubule - the hemoglobin passes into the urine.
The most frequent causes of hemoglobinuria include:
- Acute glomerulonephritis;
- Extensive burns;
- Kidney tumors;
- Malaria;
- Paroxysmal nocturnal hemoglobinuria;
- pyelonephritis;
- Renal infarction;
- Sickle cell anemia;
- Tuberculosis of the urinary tract;
- Autoimmune hemolytic anemia;
- CID (disseminated intravascular coagulation);
- Hemolytic uremic syndrome;
- Reactions to incompatible blood transfusions;
- Immunohemolytic anemias from drugs (eg methyl-dopa or penicillin);
- Cold hemoglobinuria;
- Favism;
- Malfunctioning heart valve prosthesis;
- Intense and prolonged physical efforts (stress hemoglobinuria, typical for example of runners, walkers and those who make long use of a pneumatic hammer).
The therapy of hemoglobinuria is essentially etiological, that is aimed at the treatment of its causes of origin.
