Thrombocytopenia – causes of low platelets inof blood

Update: December 2018

Various diseases of the circulatory system in which the total
the number of platelets below normal, united by a common name –
thrombocytopenia. The physiological norm of the amount of content
platelets in humans is on average 180 – 400 x 10
9/л. Pathological abnormalities in the platelet system,
especially a quantitative reduction in the number of platelets may be
cause (in 80%) of nosebleeds, profuse and prolonged
menstruation, bleeding from the gums, hemorrhages under the skin and during
internal organs.

Platelet function in the body

Platelets (blood plates) form mainly in the bone.
brain of large cells of megakaryocytes and are in the form of nuclear-free
round or oval plates with a diameter of 2 to 4 microns. On their
the membrane has receptors consisting of glycoprotein
complexes. Thanks to them, the plates can be activated,
become spherical and form characteristic outgrowths
(pseudopodia). They are connected (aggregation)
platelets with each other and fixation (adhesion) to the vascular wall in
places damaged by the latter. They stick to the fibrin filaments,
while freeing the enzyme thrombostenin, which leads to compaction
and twisting yarns.

When stimulated, platelets also release from their granules.
компоненты, участвующие в свертываемости of blood, и другие
biologically active substances, some of which they carry on
surfaces – calcium ions, peroxidase, platelet fibrinogen
and platelet growth factor, serotonin, immune complexes,
substances that support vasospasm and others. So
way, distributed in the bloodstream along the walls of blood vessels and
interacting with them, they take part in:

  • the formation of a clot, a primary thrombus that provides
    temporary stop bleeding from small vessels as a result
    closure at the site of damage;
  • maintenance of spasm (narrowing) of vessels and in their nutrition
    (angiotrophic function);
  • immune processes;
  • fibrinolysis (clot dissolution).

Что значит низкие тромбоциты в анализе of blood? Physiological
the change in their number is about 10% during the day, and in women
loss of platelets during menstruation can reach 20 –
50%.  Only very low diagnostic value.
уровень тромбоцитов в of blood — ниже 100 х 109/л.

Pathological disorders of the platelet system may be
cause (in 80%) of nosebleeds, profuse and prolonged
menstruation, bleeding from the gums, hemorrhages under the skin and during
internal organs.

The life span of platelets is 8 to 10 days. By the end of this term they
decrease in volume. A decrease below 7.0 fl occurs, for example,
after removal of the spleen and with such a rare hereditary
diseases like Wiskott-Aldrich syndrome. It is characterized
triad: thrombocytopenia, immunodeficiency and skin eczema.

Therefore, in the study of analyzes is of great importance and
low average platelet volume (MPV), which is normally
from 7.4 to 10.4 fl.

Mechanism of thrombocytopenia

Mechanisms for implementing the causes of thrombocytopenia in adults and children
consist in:

  • Decreasing the number or in the complete absence of megakaryocytes, then
    There is a decrease or termination of their products.

Низкие тромбоциты в of blood This can occur in
результате заболеваний of blood, печени и щитовидной железы,
alcohol intoxication and exposure to toxic substances,
various viral infections, with long-term intake of some
antibiotics, the effects of ionizing radiation, with folic acid deficiency
кислоты и витамина B12. For example, when
HIV-associated conditions affect the megakaryocytes themselves, and
anti-HIV drugs sometimes damage the bone marrow (see
symptoms of HIV infection).

  • Increased destruction of platelets

Occurs with disseminated intravascular syndrome
coagulation, platelet destruction of an immune nature
(thrombocytopenic purpura, or Verlgof’s disease), with
инфекционных болезнях, после переливаний of blood, а также в
the result of taking certain medications (hypothiazide,
sulfonamides, antiallergic), etc.

  • Disturbance of the distribution of blood platelets

In the physiological state, up to 45% of them are located in the depot, which
is the spleen. If necessary, they come from the depot to
bloodstream additionally. In chronic hepatitis, malaria,
туберкулезе, некоторых заболеваниях of blood количество депонированных
platelet count can increase up to 90%. With a long delay in
spleen is reduced in their volume and increased
destruction.

So образом, низкие тромбоциты в of blood могут быть
self-inherited disease or complication of other
any disease, as well as the effects of medication
drugs and other substances.

Some types of thrombocytopenia

This syndrome can be congenital or acquired. TO
congenital, except Wiskott-Aldrich syndrome, include syndrome
Fanconi and giant platelet syndrome, isolated
thrombocytopenia and others. Much more common
acquired diseases. AT turn u overwhelming
большинства из них причиной низких тромбоцитов в of blood являются
immune reactions. These diseases depending on the mechanism
are divided into:

  • Alloimmune resulting from the destruction of platelets
    при несовместимости групп of blood и при наличии антитромбоцитарных
    antibodies.
  • Трансиммунные —  в этом случае готовые аутоантитела от
    mothers suffering from autoimmune thrombocytopenia enter through
    placenta to the fetus.
  • Heteroimmune, which are associated with the appearance in the body of a new
    antigen or virus defeat the protein structure of the blood
    plates, causing the body to produce against them
    antibodies.
  • Autoimmune – the body produces antibodies to the protein
    platelet count, mistakenly accepting it as alien (autoimmune
    thrombocytopenia). They can occur with oncology, systemic
    аутоиммунных заболеваниях, при краснухе, герпесе, ATИЧ, при приеме
    some medicines.

Thrombocytopenic purpura

TOак симптоматическая форма заболевание встречается при
lymphogranulomatosis, hepatitis, chronic systemic diseases
connective tissue (rheumatoid arthritis, systemic red
lupus, etc.), lymphocytic leukemia, lymphoma, etc.

AT тех случаях, когда причинные первичные заболевания отсутствуют
or it is not possible to establish them, an independent diagnosis is made, or
idiopathic thrombocytopenia, which is also called
thrombocytopenic purpura. Chronic forms are called a disease.
ATерльгофа. Autoimmune idiopathic thrombocytopenia is
approximately 95% of all diseases with this syndrome.

AT зрелом возрасте они протекают в основном хронически и в 5%
result in death
bleeding or hemorrhagic strokes (cerebral hemorrhage).
The disease often affects people at a young age, especially
women. Idiopathic thrombocytopenia occurs in children
mostly in acute form. AT 75% случаев она заканчивается
complete recovery.

Symptoms of thrombocytopenia

They are caused not only by the coagulation disorder
(coagulating) mechanisms, but also increased permeability
vascular walls. The first phase of the mechanism is violated.
coagulation – the formation of thromboplastin is disturbed, retraction
(due to lack of an appropriate enzyme). Elevated
vascular permeability is also due to blood deficiency.
plates, since their regional arrangement is absent and
angiotrophic (nutritional) processes, there is a lack
serotonin, which is also produced in platelets and possesses
spastic effect on blood vessels. Main symptoms of thrombocytopenia
following:

  • subcutaneous multiple hemorrhages of various sizes – from
    petechial (small-point) lesions, prone to merge, to
    large spots and hemorrhages; they arise
    independently or with minor, even not always noticeable,
    physical effects on fabric
  • elements of the rash have different colors (blue, brown, red,
    yellow, greenish), which indicates a different time of their
    appearances
  • localization – the front surface of the chest and
    limbs, anterior abdominal wall, face, and oral mucosa;
    bleeding from the mucous membranes of the nose and gums, which are often
    are quite intense; heavy and prolonged bleeding
    during and between menstruations, which are often
    the only symptom of the onset of the disease; most dangerous bleeding
    after tonsillectomy, removal of adenoids or extraction of teeth
  • hemorrhages under the conjunctiva and in the retina
  • bleeding from the esophagus, stomach, hemorrhoidal veins, organs
    urination, hemorrhage in the brain
  • very rarely is a slight enlargement of the spleen – this
    is a hallmark of other types of thrombocytopenia,
    where the spleen is large
  • recurrent nature of the disease for six months (with
    chronic forms).

Low platelets in pregnancy and in children

Thrombocytopenia during pregnancy rarely occurs in the form of acute
or severe form. However, it increases the threat 2–3 times.
spontaneous interruption in the first 6 months leads to early
the occurrence of gestosis, miscarriages, and in the second half
pregnancy – to premature resolution of childbirth. ATо время родов
there is a risk of heavy bleeding.

Often there is a remission in chronic
заболевания, связанная с увеличением содержания в of blood беременных
corticosteroid hormones and their fetus. However, for women,
chronic sufferers with frequent relapses and difficult
correction, pregnancy is undesirable.

The frequency of diseases among children is 3 – 5 per 100 thousand,
in all cases, the main symptom of low platelet
children are petechial (spotted) rash (100%), in 30%
there may be nasal bleeding, bleeding gums – up to 20%.

Diagnostics

The diagnosis is established based on the nature of the rash and
clinical course of the disease. From laboratory studies
The main results are:

  • Significant reduction in platelet count or their the absence of.
  • The decrease in their average volume.
  • Decreased speed or lack of blood clot retraction.
    If blood taken from a vein normally coagulates within 2 hours
    with the separation of serum, then a thrombocytopenia clot can
    stay loose for more than 6 hours and even several days.
  • Increase lab time test results
    bleeding.
  • The presence of antibodies to thrombocytes (thromboagglutinins and
    thrombolysis).
  • Decreased platelet grit.
  • Detection in the blood of platelets of different colors (platelets
    blue color) and different forms (changing their pseudopodia).
  • Anemia and leukopenia as comorbid underlying disease or
    bleeding (minor signs).
  • In studies of bone marrow punctate detected
    increase in the number and volume of megakaryocytes, their loss of granules,
    vacuole formation, lack of synchronicity. Their number
    may be normal or decrease (up to complete disappearance)
    with the recurrence of the disease. This may be due to an increase in the number
    antiplatelet antibodies.

The basic principles of treatment

The main treatment for thrombocytopenia with severe bleeding
is to transfuse platelet mass and plasma, but to do
It is necessary with caution. When identified in the analyzes
anti-platelet antibodies from this should be abandoned due to
возможного усиления bleeding.

For stopping bleeding or reducing bleeding
etamzilat sodium, epsilonaminocaproic acid
intravenous and oral, hemostatic sponge, thrombin, adipate
serotonin, calcium chloride solution, iron preparations, vitamins.
In case of large blood loss and severe anemia,
erythrocyte mass and plasma replacement transfusion.

To suppress immune responses and reduce vascular
permeability prescribed glucocorticosteroid drugs
(prednisone, dexamethasone), the dose of which is gradually reduced
after relief of bleeding. Supportive
hormone therapy is carried out for one to several
months, depending on the severity of the disease.

With the ineffectiveness of the ongoing conservative therapy, as well as
with repeated heavy bleeding or hemorrhage in the vital
important organs recommended removal of the spleen (splenectomy).
Splenectomy is often effective (up to 80%), especially in
young. This is due to a decrease in platelet destruction,
reduction of antibody formation and elimination of the inhibitory effect
spleen on platelet production by the bone marrow.

In the absence of the effect of all the listed types of treatment
immunosuppressants are prescribed. However, the negative impact on
blood formation and immunity limits their use. Forecast
thrombocytopenic purpura in most cases
favorable.

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