CHAPTER TWO: PROJECT WORK ON POLYCYTHEMIA

CHAPTER TWO

2.1 LTERATURE REVIEW

2.2 EFFECT OF POOR ORAL HYGIENE

2.3 PREVENTION OF POOR ORAL HYGIENE

2.4 BENEFICIAL FOODS FOR THE TEETH

2.5 HARMFUL FOODS FOR THE TEETH

2.6 ORAL HYGIENE GUIDELINES FOR CHILDREN AND BABIES

 

CHAPTER TWO

2.0   LITERATURE REVIEW

Polycythemia is a condition that results in an increased level of circulating red blood cells in the bloodstream. People with polycythemia have an increase in hematocrit, hemoglobin, or red blood cell count above the normal limits.

Polycythemia is normally reported in terms of increased hematocrit (hematocrit is the ratio of the volume of red blood cells to the total volume of blood) or hemoglobin concentration (hemoglobin is a protein responsible for transporting oxygen in the blood). ( Siamak N. Nabili, MD, MPH at medicinenet)

2.1   ABSOLUTE POLYCYTHEMIA

The overproduction of red blood cells may be due to a primary process in the bone marrow (a so-called myeloproliferative syndrome), or it may be a reaction to chronically low oxygen levels or, rarely, a malignancy. Alternatively, additional red blood cells may have been received through another process—for example, being over-transfused (either accidentally or, as blood doping, deliberately) or being the recipient twin in a pregnancy, undergoing twin-to-twin transfusion syndrome.( Charles Patrick Davis, MD, PhD)

• Hematocrit (HCT): Polycythemia is considered when the hematocrit is greater than 48% in women and 52% in men.
• Hemoglobin (HGB): Polycythemia is considered when a hemoglobin level of greater than 16.5g/dL in women or hemoglobin level greater than18.5 g/dL in men.

Polycythemia can be divided into two categories; primary and secondary.

2.2   Primary polycythemia: In primary polycythemia the increase in red blood cells is due to inherent problems in the process of red blood cell production.

2.3   Secondary polycythemia: Secondary polycythemia generally occurs as a response to other factors or underlying conditions that promote red blood cell production.

Red cell production (erythropoiesis) takes place in the bone marrow through a complex sequence of tightly regulated steps. The main regulator of the red cell production is the hormone erythropoietin (EPO). This hormone is largely secreted by the kidneys, although, about 10% may be produced and secreted by the liver.

Erythropoietin secretion is up-regulated in response to low oxygen levels (hypoxia) in the blood. More oxygen can be carried to tissues when erythropoietin stimulates red blood cell production in the bone marrow to compensate for the hypoxia.

Neonatal (newborn) polycythemia can be seen in 1% to 5% of newborns. The most common causes may be related to transfusion of blood, transfer of placental blood to the infant after delivery, or chronic inadequate oxygenation of the fetus (intrauterine hypoxia) due to placental insufficiency.( medicinenet.com,Charles Patrick Davis)

2.4   CAUSES OF POLYCYTHEMIA

Causes of polycythemia are primary or secondary. In primary polycythemia, abnormalities in red blood cell production cause an increase in red cell count. In secondary polycythemia, factors external to red blood cell production (for example, hypoxia, sleep apnea, certain tumors) result in polycythemia.

2.4.1        CAUSES OF PRIMARY POLYCYTHEMIA

Primary polycythemias are due to acquired or inherited genetic mutations causing abnormally high levels of red blood cell precursors. Primary familial and congenital polycythemia (PFCP) and polycythemia vera (PV) are in this category.

2.4.2        POLYCYTHEMIA VERA

Polycythemia vera is a rare condition. One study indicated that there were 65,243 patients with PV in the United States in 2003. Polycythemia vera is typically associated with an elevated white blood cell count (leukocytosis) and platelet count (thrombocytosis). An enlarged spleen (splenomegaly) and low erythropoietin levels are other clinical features of polycythemia vera.

Until recently, the exact mechanism of polycythemia vera was not well understood. In 2005, genetic mutations of the JAK2 gene were found to be responsible for most cases of polycythemia vera. These mutations are thought to possibly increase the sensitivity of the red blood cell precursors to erythropoietin, thereby, increasing red blood cell production.

2.4.3      PRIMARY FAMILIAL AND CONGENITAL POLYCYTHEMIA

(PFCP)

Primary familial and congenital polycythemia (PFCP) is also thought to be caused by genetic mutations resulting in increased responsiveness to normal levels of erythropoietin. Most cases are caused by different mutations to the EPOR gene.

2.4.4        COMMON CAUSES OF SECONDARY POLYCYTHEMIA?

Secondary polycythemia is usually due to increased erythropoietin (EPO) production either in response to chronic hypoxia (low blood oxygen level) or from an erythropoietin secreting tumor.

2.4.5        CHRONIC HYPOXIA

Common conditions causing chronic hypoxia are chronic lung diseases such as:

• emphysema and chronic bronchitis which are collectively known as chronic obstructive pulmonary disease (COPD) or hypoventilation syndrome,
• chronic heart diseases (congestive heart failure, or abnormal flow of blood from the right side to the left side of the heart),
• sleep apnea, and
• pulmonary hypertension.

Abnormal blood flow to the kidneys can be perceived by the kidneys as decreased oxygenation (renal hypoxia), even though, other tissues may have normal oxygenation. Renal hypoxia may promote an increase in erythropoietin production. This condition can occur after kidney transplantation or narrowing of renal arteries (blood vessels supplying the kidneys).

People living in high altitudes can develop polycythemia. In high altitudes, increased red blood cell production occurs in order to compensate for the low ambient oxygen levels and inadequate tissue oxygenation.

Rare congenital defects in the hemoglobin molecule, such as 2, 3-BPG deficiency, can result in a higher oxygen affinity by hemoglobin. In these conditions, oxygen is held on tightly by hemoglobin and is less readily released from hemoglobin to the tissues. The resulting tissue hypoxia from poor oxygen delivery may lead to polycythemia.( Siamak . Nabili)

2.4.6        ERYTHROPOIETIN SECRETING TUMORS

Certain tumors can release increased amount of erythropoietin. The most common erythropoietin secreting tumors are:

• liver cancer (hepatocellular carcinoma),
• kidney cancer (renal cell carcinoma),
• adrenal adenoma (adenocarcinomas), and
• uterine (womb) tumors.

Occasionally, benign kidney cysts and kidney obstruction (hydronephrosis) can also secrete extra erythropoietin causing polycythemia.

A rare genetic condition, called Chuvash polycythemia, causes increased activity of the gene that produces erythropoietin. The overproduction of erythropoietin causes polycythemia.

2.5   POLYCYTHEMIA VERA

Polycythemia vera is a blood cancer that begins in the marrow of the bones, the soft center where new blood cells grow. With polycythemia vera, the marrow makes too many red blood cells, which causes the blood to get too thick. That can most likely to have blood clots, a stroke, or a heart attack.

Polycythemia vera develops very slowly, usually over many years. Although it can be life-threatening if not treated, most people have a good chance to live a long life when they get the right care.

Polycythemia vera often starts around 60years or older, although it can happen at any age. It's more common among men than women.

You might have some warning signs like dizziness or feeling tired and weak. But it's likely you'll first learn you have it when a routine blood test shows that you have a high number of blood cells.

Polycythemia vera occurs when a mutation in a bone marrow cell causes a problem with blood cell production. Normally, the body carefully regulates the number of each of the three types of blood cells. But in polycythemia vera, the mechanism that body uses to control the production of blood cells becomes damaged, and the bone marrow makes too many of some blood cells (UT at Austin medicinenet)

2.5.1        CAUSES OF POLYCYTHEMIA VERA

The mutation that causes polycythemia vera is thought to affect a protein switch that tells the cells to grow. Specifically, it's a mutation in the protein JAK2 (the JAK2 V617F mutation). Most people with polycythemia vera have this mutation. There are other mutations found in people with polycythemia vera, but it's not yet known what role these mutations play in the development of the disease or what the implications of these mutations might mean for treating the disease.

It's not clear what causes the mutations seen in polycythemia vera. Researchers believe the mutation occurs after conception — meaning that your mother and father don't have it — so it's acquired, rather than inherited from a parent.

Polycythemia vera is a disorder of the bone marrow. It mainly causes too many red blood cells to be produced. The numbers of white blood cells and platelets may increase as well..

This is a rare disorder that occurs more often in men than in women. It is not often seen in people under age 40. The problem is often linked to a gene defect called JAK2V617F. The cause of this gene defect is unknown.

2.5.2        SIGNS AND SYMPTOMS OF POLYCYTHEMIA VERA

Polycythemia vera (PV) develops slowly. The disease may not cause signs or symptoms for years.

When signs and symptoms are present, they're the result of the thick blood that occurs with PV. This thickness slows the flow of oxygen-rich blood to all parts of your body. Without enough oxygen, many parts of your body won't work normally.

The signs and symptoms of PV include:

• Headaches, dizziness, and weakness
• Shortness of breath and problems breathing while lying down
• Feelings of pressure or fullness on the left side of the abdomen due to an enlarged spleen (an organ in the abdomen)
• Double or blurred vision and blind spots
• Itching all over (especially after a warm bath), reddened face, and a burning feeling on your skin (especially your hands and feet)
• Bleeding from your gums and heavy bleeding from small cuts
• Unexplained weight loss
• Fatigue (tiredness)
• Excessive sweating
• Very painful swelling in a single joint, usually the big toe (called gouty arthritis)

In rare cases, people who have PV may have pain in their bones

2.5.3        POLYCYTHEMIA VERA COMPLICATIONS

If you have PV, the thickness of your blood and the slowed blood flow can cause serious health problems.

Blood clots are the most serious complication of PV. Blood clots can cause a heart attack or stroke. They also can cause your liver and spleen to enlarge. Blood clots in the liver and spleen can cause sudden, intense pain.

Slowed blood flow also prevents enough oxygen-rich blood from reaching your organs. This can lead to angina (chest pain or discomfort) and heart failure. The high levels of red blood cells that PV causes can lead to stomach ulcers, gout, or kidney stones.

Some people who have PV may develop myelofibrosis (MY-e-lo-fi-BRO-sis). This is a condition in which your bone marrow is replaced with scar tissue. Abnormal bone marrow cells may begin to grow out of control.

This abnormal growth can lead to acute myelogenous (my-eh-LOJ-eh-nus) leukemia (AML), a cancer of the blood and bone marrow. This disease can worsen very quickly.

Polycythemia vera is a bone marrow disease that leads to an abnormal increase in the number of blood cells. The red blood cells are mostly affected.