Generality
The hematocrit is the relationship between the plasma and the figurative elements of the blood (platelets, red and white blood cells).
Since the corpuscular part of the blood consists mostly of erythrocytes or red cells, the hematocrit can also be defined as the percentage ratio between red blood cells (erythrocytes) and the liquid part of the blood, called plasma.
Going then to evaluate the ratio, in terms of percentage height, between the figured elements and the total blood volume, the value of the hematocrit is obtained.
To accelerate the sedimentation process the test tube can be centrifuged, obtaining, thanks to the sedimenting action of the centrifugal force, a clear separation between the figurative elements, which are deposited on the bottom of the test tube, and the straw yellow liquid above them (plasma) .
The number that expresses the percentage of cells piled up on the bottom, is called a hematocrit.
What's this
The hematocrit expresses the relationship between the liquid part of the blood (plasma) and the corpuscular part, that is the one occupied above all by the red blood cells.
The hematocrit is an index expressed through a percentage or a fraction. For example, a hematocrit value of 35% means that there are 35 ml of red blood cells in 100 ml of blood.
Hematocrit values that are too high or too low may be the indicator of some diseases.
Why do you measure
The hematocrit reflects both the number of red blood cells and their volume (average corpuscular volume or MCV).
This examination is indicated as part of routine examinations or when the doctor suspects that the patient is suffering from anemia (low hematocrit) or polycythemia (high hematocrit).
Furthermore, the hematocrit is useful for assessing the state of hydration .
When prescribed
The hematocrit is prescribed as a general check to assess the state of health, generally together with the hemoglobin test or as part of the blood count .
This index can also be used to evaluate and monitor at regular intervals those pathological conditions that involve changes in red blood cells, such as anemia or polycythemia.
The hematocrit indicates the existence of a problem with the production of red blood cells and / or with their survival, but does not indicate the underlying cause. For this reason, increases or decreases in the hematocrit must be interpreted together with other parameters, such as the value of hemoglobin, reticulocyte count and / or red cell indices (MCV, MCH and RDW).
In general, the hematocrit reflects the result of the red blood cell count and hemoglobin test.
Normal values
Under normal conditions, the value of the hematocrit is slightly higher in men who, thanks to greater secretion of testosterone, have a higher concentration of red blood cells in the blood.
Let us remember, in this regard, that red blood cells are produced in the bone marrow, under the stimulating action of erythropoietin, a hormone produced in the kidney in response to various stimuli (including testosterone).
Normal hematocrit values (Hct) | |
MAN | WOMAN |
38-52% | 36-46% |
CHILDREN: | |
newborns: 45-75% 1 month: 30-55% 6 months: 34-46% from 1 to 4 years: 33-44% 10 years: 36-43% | |
In addition to the stimulating action of testosterone, the kidney is particularly sensitive to blood oxygen levels. When these are scarce, there is a greater secretion of erythropoietin (even 1, 000 times higher) which, by increasing the synthesis of new erythrocytes, ensures more efficient transport of oxygen to the tissues.
This explains, for example, the natural increase in hematocrit in response to prolonged stay in high ground. The variations of this parameter, commonly found in classic blood tests (blood count), can be linked to numerous other factors, some physiologic, others pathological. We see the most common.
High hematocrit - Causes
Possible causes
1) Dehydration
- Excessive sweating: due to dehydration the liquid part of the blood is reduced; consequently the ratio between figurative and plasma elements increases and with it the hematocrit.
- It should be noted that dehydration can be induced, not only by excessive sweating, but also by the use of diuretics, burns, vomiting, diarrhea and diabetes (glycemic values above 180 mg / dl are accompanied by urinary elimination of glucose which, for osmotic gradient, brings with it considerable amounts of water).
- Cholera, a disease that causes massive water loss through faeces, also causes significant hematocrit upsets.
- In all these cases the hematocrit value does not correspond to an actual increase in circulating erythrocytes (therefore one speaks of haemoconcentration). There are therefore falsely high values of the corpuscular part, although a normal number of erythrocytes is present inside.
2) Other possible causes
- Stay at a height of over 2, 500 meters for at least a week (see: training and altitude)
- Acute renal failure
- Polycythemia or absolute poliglobulia (increase in the number of red blood cells, with a normal plasma component)
- Taking doping drugs: testosterone and derivatives; erythropoietin and derivatives (generically defined as epoetins) of second generation (Aranesp® and Nespo®: darbepoetina alfa) and third generation (Mircera ®: Cera)
- Lung diseases
- Congenital cardiovascular diseases
Because it's dangerous
Too dense blood encounters greater difficulties in its path. Consequently, the heart must contract with greater force to overcome the peripheral resistances and give the blood considerable pressure.
For this reason, a hematocrit that is too high can worsen pre-existing cardiac pathologies and overcome the resistance of the vessels causing, for example, a very dangerous cerebral hemorrhage.
A high hematocrit also promotes the formation of blood clots (thrombi), which can go to occlude important vessels, with all the negative consequences of the case (heart attack and stroke in the most serious cases).
Low hematocrit - Causes
Possible causes
- Pregnancy (from the third trimester) and prolonged aerobic training: these conditions are associated with hypervolemia, ie an increase in the total volume of blood present in the body.
- In these cases the value of the hematocrit is misleading, as it is lower than the norm, although the blood contains an adequate amount of red blood cells. It should be noted that in athletes a reduction in hematocrit values due to an increase in the liquid part of the blood improves performance levels. In fact, with the same circulating red blood cells, a more fluid blood will encounter less resistance along its path, with a consequent increase in stroke volume and blood flow to the tissues.
- Iron deficiency
- Vitamin B12 deficiency
- Folic acid deficiency
- Leukemia
- Malignant tumors
- Anemias (a. Hemolytic from autoimmunity or red blood cell defects; aplastic anemia; sickle cell anemia etc.)
- Liver cirrhosis
- Serious infections
- Chronic renal failure
- Acute or chronic bleeding of the digestive tract or other organs (such as bladder or uterus) or following severe trauma (blood loss causes a decrease in both the plasma and corpuscular portion)
- Decreased production of hemoglobin (eg thalassemia)
- Exposure to toxins and radiation
- Chronic inflammatory disorders
Because it's dangerous
Pallor, weakness, headache, reduced vision, malaise and easy fatigue: these are just some of the symptoms classically associated with the pathological reduction in the number of circulating red blood cells.
How to measure it
Usually, the analysis is performed using automated tools that measure various parameters.
To measure the hematocrit, the patient must have a blood sample taken from a vein in the arm or by a puncture of the finger or heel (newborns).
The test tube containing the blood sample is then centrifuged, obtaining a clear separation between the red blood cells, which are deposited on the bottom, and the plasma above them. The hematocrit expresses the percentage quantity of cells piled up on the bottom.
Preparation
It is not necessary to be fasting to have a blood sample useful for the evaluation of blood count. The examination takes place, in fact, on the corpuscular part of the blood, that is on the cells, for which the fact of having taken food or drink has no influence.
However, if in addition to the blood count, you must perform some other blood test that includes fasting (such as the determination of blood sugar or cholesterol) it will be necessary to abstain from food and drink. The general practitioner who prescribes the analyzes will still be able to provide useful information for the case.
It must be remembered that a recent blood transfusion can distort the result of the hematocrit.
Interpretation of Results
High hematocrit
When the hematocrit is high, it means that the blood is denser; this can have repercussions on the heart, which makes it more difficult to pump it to send it into circulation. Furthermore, the increased blood density favors the formation of clots, which can predispose to heart attack or stroke.
Dehydration, polycythemia vera, acute renal failure and some lung diseases are among the conditions associated with hematocrit values above the norm.
Low hematocrit
There are numerous causes for which the value of the hematocrit may be low. These range from iron deficiency anemia (from iron deficiency) to bleeding, from prolonged aerobic training to chronic renal failure.
The Pantani case
THE FACTS OF MADONNA DI CAMPIGLIO
On June 5, 1999, in Madonna di Campiglio, the cyclist Marco Pantani was excluded from the Giro d'Italia after finding a high hematocrit value (52%). As required by the regulations of the time, a hematocrit rate above the 50% threshold required - for CAUTION - the suspension of the cyclist for 15 days. This precaution was justified by the fact that an hematocrit too high subjects the cardiovascular system to excessive stresses and potentially dangerous for the athlete.
The news went around the world, the "Pirate" had to abandon the Giro d'Italia and suddenly all his sporting achievements were questioned.
That fateful June 5 the group was preparing to face the penultimate stage of the Corsa Rosa, which Pantani was dominating with incredible ease. His epic uphill feats, such as those of '98 (the year he won the Giro d'Italia and the Tour de France), that crystalline and contagious smile during the celebrations, his unique way of dancing uphill ... constantly raising the 'gait, like a featherweight that insists on fighting against a heavy weight, without bending to fatigue and pain, advancing under the blows of the adversary up to bringing it down, shot after shot ... they had passionate and thrilled the whole country .
Thanks to Marco, Italian cycling was experiencing one of its most intense and bright periods. But threatening clouds chased each other on the horizon; were the years of doping scandals, of disconcerting revelations, of searches, arrests, reckless checks. The reflectors of the media, for better or for worse, were all focused on cycling, committed to illuminating everything that could create odience and sensation: the champions on one side, doping on the other.
A broken mirror with a punch in his hotel room and words spoken in front of journalists with shining eyes, indelible memories in the minds of the fans: " After a lesson of this type, even grudgingly I must say that, if this happens to one sportsman like me who has given so much to this sport, there is to think ... I already had the pink jersey, I had 46 of hematocrit and today I wake up with this surprise ... I think there is something definitely strange ... I left again after big accidents, but morally we touched the bottom this time ".
Something that day broke irretrievably in the mind of the Champion; Pantani could have returned to the saddle after the 15-day suspension to demonstrate on the roads of the Tour de France that he is stronger than everything and everyone, false accusations, hypocrisies, suspicions, the evil that depicted him as "the doped d 'Italy". Unfortunately it was not so, from that day Marco was the victim of a real media and judicial persecution, cannon fodder to break up piece piece to feed the hunger for popularity of some unscrupulous magistrates and journalists. Flashes of light - like the two victories in the Tour de France the following year - alternated with increasingly dense and dark clouds, full of anger and fear; 5 years later, on February 14, 2004, only 34 years old, Marco Pantani died alone in a room of a residence in Rimini. It was an apparent suicide due to the massive ingestion of cocaine, but much remains to be clarified. It was the day of lovers, a love that can take various forms, a love that can be betrayed; the love for the bicycle for example, the same love that brought Marco to sleep with his bicycle in his bedroom, to bathe her in the tub, to suffer uphill, for the fans, for the family, but above all for himself same; the love for his ex-girlfriend, Christine, who a few months before had left him after years lived together in joys and sufferings, steps taken together for better or for worse, but together; the love of the fans who still remember him with renewed affection.
WHY Pantani was innocent
Numerous elements lead us to believe that Pantani was innocent:
- first of all common sense; in the environment it was well known that the day, or in any case the following one, there would be anti-doping controls and he was certain that - given his position in the general classification - Pantani himself would have been controlled. Not surprisingly, the evening before, the tests conducted by the medical staff of the "Pirate" attested the normality of his blood values. Furthermore, it must be said that if some anomaly had been detected that evening, the same doctors could have returned the hematocrit values below the normality threshold to pass the checks. It is difficult to think that the Medical Staff of the Mercatone Uno (Pantani team) has committed a similar lightness.
- There were procedural anomalies during collection that violated the most elementary rules foreseen by the controls. In particular - from the stories of the same Pantani, the doctor who assisted him during the checks and his trainer / physiotherapist Stefano Borra - it emerges that:
- the blood taken from Pantani was NOT divided on two test tubes, one for analysis and one for counter-analysis.
- this single tube was not placed in the special refrigerated container, but the examiner put it in his pocket, after having passed it in front of Pantani's face, saying: "Do you see it? Do you see that it is yours? Then we don't want stories!"
- already the evening before the checks, as revealed by other cyclists of the Mercatone Uno, rumors began to circulate about the positivity of Pantani. It is also said that in the hotel where Pantani was staying there was an unusual concentration of journalists even before the news was officially communicated.
- Pantani had already been checked at other times in that Giro and had turned out well, as was the case with all the other checks carried out in his life. Moreover, even wanting to believe that his hematocrit was actually elevated, this is not necessarily synonymous with doping. MAI was found a trace of doping substances in the blood of Marco Pantani. Furthermore, consider that many factors influence the value of the hematocrit, including:
- diet and physical activity in the days preceding the determination
- height
- position of the subject in the minutes preceding the withdrawal (at 7.30 am, when the check was carried out, Pantani was presumably sleeping in bed)
- time of day when the withdrawal is made
- use of the lace for the collection (as happened in the case of Pantani, it can cause an increase in the hematocrit of the order of 2.5 - 5%)
- On the same afternoon of 5 June, Pantani underwent private examinations in Imola, in a laboratory accredited by the UCI, and his values were perfectly in line with those found by his medical staff the previous evening.
- The hemoglobin values recorded in the internal analyzes, in the anti-doping control, and in the Imola tests were absolutely superimposable. Since the hematocrit mainly depends on the amount of red blood cells and given that they contain hemoglobin, an increase in hematocrit values is expected as the latter increases. Normally, the Hct values are about 3 times higher than the Hb values: for example, if the hemoglobin values are 15g / dL a hematocrit is expected equal to 45%. If this relationship is noticeably lost in a healthy athlete, either we are in the presence of severe dehydration or there has actually been some abnormality in the controls.
EMATOCRITUS ALTERATIONS AND PLATE VALUES
Since the hematocrit corresponds to the ratio between the liquid part and the solid part of the blood, to alter its values, just remove a few drops of the upper liquid part (plasma) and throw them away. The hematocrit values will be "magically" increased, but with a substantial difference: fewer platelets will remain in the test tube because a part has been eliminated together with the taken plasma. The same anomaly can be registered if an insufficient amount / quality of anticoagulant is used.
Well, in the sample of anti-doping taken from Marco the platelet values appear inexplicably low, clearly lower than the normal values of a healthy person, clearly inferior to what is recorded by the internal controls of the team, clearly lower than the values commonly found in the blood of Pantani to the previous anti-doping controls, clearly lower than the values recorded in the samples taken from the other riders involved in the checks of that June 5th.
MEDICAL OR COMPLETE ERROR?
Having ascertained that with very high probability Pantani's hematocrit was normal, it is necessary to ask why the cyclist "turned out" to be a doping control.
Medical error or conspiracy? In this regard, only assumptions can be made.
- CLANDESTINE SCOMMETTES: Pantani companies had ignited the enthusiasm of Italians on cycling; thanks to the media hype and the overwhelming athletic superiority, in '99 there were really many bets on the Romagna cyclist (about 200 billion lire, according to the declarations of Pantani himself). Reversing the predictions of a victory that seemed almost certain, would have meant enormous profits in the illegal betting sector. This hypothesis, which is nowadays considered the football-betting scandals, was confirmed by the testimony of the repentant Renato Vallanzasca, according to which an acquaintance of his - in prison - would have strongly advised him to bet against Pantani; despite the advantage that "the Pirate" continued to accumulate day after day, this character proved to be certain that the 1999 Giro d'Italia would not be won by Pantani.
- POPULARITY OF CYCLING: the economic interests deriving from the Pantani businesses had undoubtedly stolen popularity (and perhaps some sponsors) from football, a sport steeped in the marrow of economic interests. Just think of the share points, which in the stages of ascent quietly exceeded 50% (more than half of the people watching TV in those hours was tuned to the pink race). To think ill of others it is a sin but often we guess it .... especially when there are similar interests at stake.
- A DIFFICULT CHARACTER: in those years, Pantani became the spokesman of the general discontent of the runners on "wild" anti-doping controls, carried out without humanity in the heart in the night, with hidden cameras and searches of hotel rooms and private homes. His accusations and statements about it could have made him an "uncomfortable character" at the top of the cycling and sports federations of the time. Not only that, in the '99 Pantani assumed the role of the "cannibal", in the sense that he dominated every race suited to his characteristics of climber without leaving anything to the adversaries; this may have helped to attract dislikes of the cycling environment towards him.
- LANCE ARMSTRONG'S ASCENT: Lance Armstrong, after surviving a testicular cancer diagnosed three years earlier, won the 1999 Tour de France and the next 6. He was a team member - the US postal - which was not sponsored by a private company, but from the agency of the United States Government responsible for the country's postal services. In 2000 Pantani - also with a condition not perfect, given by the vicissitudes of the previous year - was the only athlete to seriously worry the American athlete on the climb, even managing to detach him in one stage. That was the last participation of the "Pirate" in the Tour de France, since from the following year the organizers systematically refused his entry to the race. Some conspiracy theorists see in this refusal, as in the story of the Madonna di Campiglio hematocrit, an attempt to favor the rise of Lance Armstrong. According to this hypothesis, the American government would have had every interest in favoring an American athlete who imposed himself in an exquisitely European sport, decreeing the superiority of the United States, not only in the military and economic fields, but also in sports. Without considering, then, the millionaire interests, linked to the foundation led by Armstrong himself and committed to the fight against cancer.
For the record, on August 24, 2012, the USADA (United States Anti-Doping Agency) formalized the decision to disqualify Lance Armstrong for life, to which he took away all the sports results obtained from 1998 onwards, including the seven Tour de France. The accusations of having made systematic use of doping substances were then confirmed by the admissions of Lance Armstrong himself.
On the other hand, through the analysis of the bone marrow, the autopsy on Pantani's body showed that he certainly had not used Epo (a substance used to increase the quantity of red blood cells in the blood, with consequent raising of the 'hematocrit).
