Skip to content

Polycythemia vera (NORD)

Videos

Notes

Hematological system

Pathology

Anemias
Heme synthesis disorders
Coagulation disorders
Platelet disorders
Mixed platelet and coagulation disorders
Thrombosis syndromes (hypercoagulability)
Lymphomas
Leukemias
Leukemoid reaction
Dysplastic and proliferative disorders
Plasma cell dyscrasias
Hematological system pathology review

Assessments
Polycythemia vera (NORD)

Flashcards

0 / 11 complete

Questions

1 / 2 complete
High Yield Notes
10 pages
Flashcards

Polycythemia vera (NORD)

11 flashcards
Questions

USMLE® Step 1 style questions USMLE

2 questions
Preview

 A 62-year-old man comes to his primary care physician for evaluation of daily headaches and blurry vision. These symptoms started two months ago. In addition, the patient reports feeling itchy over his body after bathing or visiting the sauna. Past medical history is notable for hypertension and asymptomatic gallstones were discovered on a recent ultrasound. The patient is a former smoker with a 20-pack-year smoking history. On the physical exam, the patient is observed to have facial plethora and a spleen palpated 2 cm below the left costal margin. Laboratory testing is ordered and the results are as follows:  

Laboratory Results
Hemoglobin  18.1 g/dL  
Hematocrit  54%  
Erythrocytes  7.2 million/mm3  
Leukocytes  12,500/mm3  
Platelets  470,000/mm3  
Uric Acid  7.9 mg/dL  

Which of the following best describes the pathophysiology of this patient’s presentation? 

Transcript

Content Reviewers:

Rishi Desai, MD, MPH

In polycythemia vera, there are increased blood cell levels due to overproduction by the bone marrow, which is a soft tissue found within the bones.

Normally, about 45% of the total blood volume is made up of erythrocytes, or red blood cells, and their main function is to carry oxygen to tissues and bring carbon dioxide to the lungs so it can be expired. This value is called the hematocrit.

In polycythemia vera there’s an increase in red blood cell production.

It typically begins with a mutation in a single hematopoietic stem cell, which gives rise to red blood cells, white blood cells, and platelets.

In 90 percent of the affected individuals there is a mutation of the Janus Kinase 2 or JAK2 gene.

Normally, the kidneys produce erythropoietin which is a hormone that binds to receptors on the hematopoietic stem cells and activates JAK2 gene.

When that happens, it causes the cell to divide and thus produce more blood cells.

However, when there’s a mutation, it keeps JAK2 gene activated, and these cells are able to divide even in the absence of erythropoietin.

The mutated cells proliferate, and rapidly become the predominant hematopoietic cells in the bone marrow.

In time these cells start to die out and that’s when scar tissue forms.

At that point, the bone marrow can no longer produce blood cells, leading to anemia or low red blood cell levels, thrombocytopenia or low platelet levels, and leukopenia or low white blood cell levels. This is known as the spent phase.

And once the disease is in the spent phase, it’s really a different disease altogether - at that point it’s myelofibrosis.

The most common symptoms of polycythemia vera are fatigue, dizziness, increased sweating, redness in the face, blurred vision, and itchy skin especially after a hot shower.

Itchiness develops due to the increased number of basophils and mast cells which contain histamine that causes itching when released.

Splenomegaly or spleen enlargement is also common because the excess red blood cells buildup in the spleen, which usually helps with removing excess cells.

High turnover of red blood cells can cause build up of uric acid which leads to the inflammation of joints or gout and kidney stones.