The number of red cells normally present varies according to a persons age and sex. Men have higher results than women do and newborn babies have higher values than adults. The presence of an elevated red cell count is called erythrocytosis or a polycythaemia. This increase in red cells may show in a blood test result as an increase in red cell number, or as a rise in haemoglobin, or packed cell volume. Red blood cell production is governed by a hormone called erythropoietin that is secreted by the kidney. Erythrocytosis is not a disease but is usually part of some other problem. There are no specific symptoms or physical signs although the underlying disease may cause the patient to seek medical help. Many times, the high hematocrit is noticed when a person has a blood count done as part of an exam for an unrelated complaint. The normal hemoglobin value in an adult male can range upto 18 g/dl. It can be raised due to many reasons and these causes may be subdivided into whether there is a true or absolute erythrocytosis (polycythemia) due to an increase in red cells or an apparent erythrocytosis when the red cells are not increased but are instead more concentrated. The secondary increase can be due to dehydration, diuretic drugs, burns, stress, or high blood pressure. True polycythemia may be primary and is then called polycythemia vera, a myeloproliferative disorder in which the RBC count increases without being stimulated by the red blood cell stimulating hormone erythropoietin.
Secondary polycythemia is due to an increase in RBC counts following an increase in the hormone erythropoietin. This hormone increase is in response to low blood oxygen, caused by heart disease or high altitude; continual exposure to carbon monoxide (heavy smoking); chronic lung disease, congenital (hereditary) disorders producing an abnormal hemoglobin or an overproduction of EPO; and diseases such as kidney disease. Symptoms of polycythemia include easy bruisability, purpuric spots on skin, blood in the stool, blood clots, painful redness of the skin & warmth in parts of the limbs, blackening of the fingers or toes (necrosis), fever, heat tolerance, weight loss, and itching. If an underlying problem is found, it can usually be corrected, and the erythrocytosis should disappear. If there is not a correctable problem, then further management depends on how high the hematocrit is. If the hematocrit is just a little above normal, perhaps nothing needs to be done. However, if the hematocrit gets too high (above 60 percent), it thickens the blood, causing circulatory difficulties that may result in strokes and heart problems. To avoid these problems, the patient can have phlebotomies (blood-letting) to reduce the hematocrit. One unit of blood can be removed every few days or once a week until the hematocrit is down and then done at intervals of time to keep it down. Phlebotomy is like donating blood though the blood cannot be used because of the underlying problem.