Q: My 37 years old husband is suffering from hypertension. He is taking Telmisartan for the last six months and now his blood pressure ranges at 120/80 mm/ Hg. His hemoglobin was 18.2 g/dl for the last 10 years but now came down to 16.9 g/dl. His hematocrit value has also come down and is presently 49. His blood counts are all in the normal range. His TIBC, serum Vitamin B12 is just a bit below normal. His serum iron is normal and EPO is 7.2. His liver function test came normal. He has no enlargement of the liver or spleen, pain, thrombosis or pruritis. A haematologist suggested that he is suffering from polycythemia and has asked him to get a Janus kinase 2 (JAK 2) test done. He also had an attack of pseudo gout three months back. Is it normal to have high haemoglobin level?

A:The number of red cells normally present varies according to a person's age and sex. Men have higher results than women do and newborn babies often 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 (EPO) 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.

Haematological values for the normal and abnormal will often overlap, and a value within the recognised normal range (reference interval) may be definitely pathological in a particular subject. As the biological reference intervals for many parameters depend on factors like patient age, sex, sample population and method of testing, it is important that the test result is viewed in the light of the clinical profile, as isolated result can often be un-interpretable.

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 (PV), 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 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, which is like donating blood. 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.

A mutation in the Janus kinase 2 (JAK2) called JAK2 V617F is found in 74 to 97% patients with polycythemia vera and can help confirm the disease in patients with high red cell counts. Please be guided by your hematologist and get the necessary tests done to help exclude the disease.