Sedentary Work Exerting up to 10 pounds (4.5 kg) of force occasionally and/or a negligible amount of force frequently or constantly to lift, carry, push, pull, or otherwise move objects, including the human body. Sedentary work involves sitting most of the time, but may involve walking or standing for brief periods of time. Jobs are sedentary if walking and standing are required only occasionally and other sedentary criteria are met.

Light Work Exerting up to 20 pounds (9.1 kg) of force occasionally and/or up to 10 pounds (4.5 kg) of force frequently, and/or negligible amount of force constantly to move objects. Physical demand requirements are in excess of those for Sedentary Work. Light Work usually requires walking or standing to a significant degree. However, if the use of the arm and/or leg controls requires exertion of forces greater than that for Sedentary Work and the worker sits most the time, the job is rated Light Work.

Medium Work Exerting up to 50 (22.7 kg) pounds of force occasionally, and/or up to 25 pounds (11.3 kg) of force frequently, and/or up to 10 pounds (4.5 kg) of forces constantly to move objects.

Heavy Work Exerting up to 100 pounds (45.4 kg) of force occasionally, and/or up to 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Very Heavy Work Exerting in excess of 100 pounds (45.4 kg) of force occasionally, and/or in excess of 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Job Classification

In most duration tables, five job classifications are displayed. These job classifications are based on the amount of physical effort required to perform the work. The classifications correspond to the Strength Factor classifications described in the United States Department of Labor's Dictionary of Occupational Titles. The following definitions are quoted directly from that publication.

Sedentary Work Exerting up to 10 pounds (4.5 kg) of force occasionally and/or a negligible amount of force frequently or constantly to lift, carry, push, pull, or otherwise move objects, including the human body. Sedentary work involves sitting most of the time, but may involve walking or standing for brief periods of time. Jobs are sedentary if walking and standing are required only occasionally and other sedentary criteria are met.

Light Work Exerting up to 20 pounds (9.1 kg) of force occasionally and/or up to 10 pounds (4.5 kg) of force frequently, and/or negligible amount of force constantly to move objects. Physical demand requirements are in excess of those for Sedentary Work. Light Work usually requires walking or standing to a significant degree. However, if the use of the arm and/or leg controls requires exertion of forces greater than that for Sedentary Work and the worker sits most the time, the job is rated Light Work.

Medium Work Exerting up to 50 (22.7 kg) pounds of force occasionally, and/or up to 25 pounds (11.3 kg) of force frequently, and/or up to 10 pounds (4.5 kg) of forces constantly to move objects.

Heavy Work Exerting up to 100 pounds (45.4 kg) of force occasionally, and/or up to 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Very Heavy Work Exerting in excess of 100 pounds (45.4 kg) of force occasionally, and/or in excess of 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Polycythemia Vera


Related Terms

  • Erythremia
  • Hyperglobulinemia
  • Myeloproliferative Disorders
  • Polycythemia Rubra
  • Primary Polycythemia
  • Waldenstr√∂m's Disease

Differential Diagnosis

  • Chronic myelogenous leukemia
  • Lung disease
  • Secondary erythrocytosis

Specialists

  • Hematologist
  • Oncologist

Comorbid Conditions

Factors Influencing Duration

The length of disability is determined by the phase at which the disease was diagnosed and the severity of symptoms.

Medical Codes

ICD-9-CM:
238.4 - Neoplasm of Uncertain Behavior, Polycythemia Vera

Overview

Polycythemia vera is an acquired disorder of bone marrow that causes an overproduction of red blood cells. This overproduction results in increased volume of the blood (hypervolemia) and thickening of the blood (hyperviscosity), both of which impair its usual rapid flow through the blood vessels to the brain, heart, gastrointestinal tract, and other tissues. The hyperviscosity of the blood and the increase in platelets increase the potential for clot formation (thromboembolism), which can result in heart attack (myocardial ischemia) and stroke.

The exact cause of polycythemia vera is unknown. It is an acquired (rather than inherited) mutation in a subset or clone of normal bone marrow cells called stem cells, leading to excessive production of blood cells. These stem cells may be abnormally sensitive to growth factors involved in blood cell production. One theory suggests a link to radiation exposure.

Polycythemia vera is associated with 3 to 5 times greater risk of peptic ulcer disease and increased risk for acute myelogenous leukemia, which develops in about 2% to 15% of individuals with polycythemia vera 8 or more years after diagnosis. About 10% of individuals progress to a "spent" phase 2 to 13 years after diagnosis. The spent phase is characterized by fibrous degeneration (fibrosis) of the bone marrow, abnormal elevation of white blood cell count (leukocytosis), and massive enlargement of the spleen (splenomegaly).

Incidence and Prevalence: Approximately 3,500 cases of polycythemia vera occur annually in the US (Altman).

Source: Medical Disability Advisor



Causation and Known Risk Factors

About 60% of individuals with polycythemia vera are males, and the disease is more common in whites than in blacks. Individuals of Eastern European Jewish (Ashkenazic) origin have the highest risk. The condition occurs most commonly in individuals aged 60 to 80 years (Altman).

Source: Medical Disability Advisor



Diagnosis

History: The onset of polycythemia vera is frequently gradual, without marked symptoms (insidious). Afflicted individuals may complain of headache, dizziness, a sensation of spinning or movement (vertigo), itchiness (pruritus), especially after warm or hot showers, reddish discoloration of the face (facial plethora), shortness of breath, breathing difficulty when lying down, and symptoms of blood clot formation (thrombosis) and vein inflammation (phlebitis).

Other symptoms include abdominal fullness and feeling full after eating a small amount of food (early satiety). These symptoms are associated with enlargement of the spleen (splenomegaly).

Physical exam: The exam may reveal a flushed, red face (facial plethora), high blood pressure (hypertension), and an enlargement of the spleen (splenomegaly) typically discovered when the physician presses on the individual's abdomen (abdominal palpation). Seventy-five percent of afflicted individuals have splenomegaly, and 30% have liver enlargement (hepatomegaly).

Tests: The most characteristic laboratory feature of polycythemia vera is an elevated red blood cell count (hematocrit) of greater than 55% to 65%. White blood cell counts greater than 12,000 (leukocytosis) occur in about 60% to 80% of individuals, and platelet counts greater than 400,000 (thrombocytosis) in about 50% to 70%. Elevated levels of leukocyte alkaline phosphatase and vitamin B12 (both related to the high white blood cell count) are found in 70% of individuals. Bone marrow biopsy confirms the diagnosis of polycythemia vera.

Source: Medical Disability Advisor



Treatment

The objective of treatment is to reduce the thickness (viscosity) of the blood due to increased red blood cell mass and to prevent bleeding (hemorrhage) and blood clots (thrombosis). Withdrawal of blood (phlebotomy or venesection) is used to treat the disorder when red blood cells are primarily affected. In the phlebotomy process, 1 unit (pint) of blood is removed weekly until the red blood cell count (hematocrit) is less than 45% of total blood mass. Removal is then repeated as needed.

If red blood cells, white blood cells, and platelets are all increased, anticancer drugs (chemotherapy) or intravenous radioactive phosphorous may be administered to control the overproduction of cells in the bone marrow. Hydroxyurea is one of the drugs frequently used and may possibly increase the risk of developing leukemia. Newer therapeutic agents include interferon alpha and anagrelide. The use of antiplatelet therapy such as aspirin is controversial because it is associated with gastric bleeding.

Source: Medical Disability Advisor



Prognosis

Polycythemia vera is a potentially fatal disease. Untreated, most individuals with polycythemia vera die within months of vascular complications. However, maintenance of the red blood cell mass at or near normal using phlebotomy, chemotherapy, or radioactive phosphorous allows for long-term survival (10 to 15 years).

About 2% of individuals treated with phlebotomy and 15% treated with chemotherapy eventually develop acute leukemia. About 5% die from complications of myeloid metaplasia, and 15% die from other cancers (neoplasms). The major causes of death in individuals with polycythemia vera are blood clots (thrombosis) and stroke.

Source: Medical Disability Advisor



Rehabilitation

Depending on complications of polycythemia vera, such as stroke or peripheral thrombosis, rehabilitation therapy may help the individual to function better with impairments. This may include physical, speech, and/or occupational therapy, depending on the specific impairment.

Source: Medical Disability Advisor



Complications

Complications of polycythemia vera include blood clots (thrombosis) that lead to stroke or heart damage from an occluded artery (heart attack), peptic ulcer disease, gastric bleeding, recurrent arthritis caused by deposits of uric acid in the joints (gout or hyperuricemia), and accumulation of fluid in the lungs due to inefficient pumping of the heart (heart failure).

Over time, polycythemia vera may convert to a condition in which bone marrow is replaced with fibrous tissue (myelofibrosis) or to a type of leukemia characterized by the spread of immature white blood cells called granular leukocytes (chronic myelogenous leukemia).

Source: Medical Disability Advisor



Ability to Work (Return to Work Considerations)

Individuals with polycythemia vera may not be able to work while recovering from complications such as stroke, thrombosis, gout, and peptic ulcer disease. Individuals receiving outpatient chemotherapy and intravenous radioactive phosphorous may require more sedentary work due to fatigue, weakness, and dizziness. Time off from work may be needed for phlebotomy and other treatment appointments.

Source: Medical Disability Advisor



Failure to Recover

If an individual fails to recover within the expected maximum duration period, the reader may wish to consider the following questions to better understand the specifics of an individual's medical case.

Regarding diagnosis:

  • Does individual have a history of blood clots (thrombosis), heart attack (myocardial infarction), or stroke? History of stomach (peptic) ulcer disease?
  • Although the onset of polycythemia vera is gradual and without marked symptoms, does individual complain of headache, dizziness, or a sensation of spinning (vertigo)?
  • Are there complaints of itchiness (pruritus), especially after warm or hot showers?
  • Does individual note reddish discoloration of the face (facial plethora), shortness of breath, or breathing difficulty when lying down? Is there a feeling of abdominal fullness after eating a small amount of food (early satiety)?
  • On exam, were high blood pressure (hypertension) and an enlargement of the spleen (splenomegaly) noted?
  • Did a complete blood count (CBC) reveal an elevated red blood cell count (hematocrit)?
  • Were levels of leukocyte alkaline phosphatase and vitamin B12 elevated?
  • Was a sample of tissue (biopsy) taken from the bone marrow to confirm diagnosis of polycythemia vera?

Regarding treatment:

  • Has individual undergone blood withdrawal (phlebotomy or venesection) if red blood cells are primarily affected? If so, has the percentage of red blood cells in the blood (hematocrit) decreased to less than 45%? If not, how many more blood withdrawals are anticipated for the hematocrit to decrease to less than 45%?
  • If red blood cells, white blood cells, and platelets are all increased, were anticancer drugs (chemotherapy) or intravenous radioactive phosphorous administered?
  • If the drug hydroxyurea is used, how much is individual's risk of developing leukemia increased?
  • Is individual a candidate for newer therapeutic agents such as interferon alpha and anagrelide?
  • How effective is treatment in controlling the disorder?

Regarding prognosis:

  • Although polycythemia vera is a fatal disease, what is the expected survival rate for the individual with maintenance of the red blood cell mass at or near normal by phlebotomy, chemotherapy, or radioactive phosphorous?
  • Has individual developed acute leukemia or other types of cancer?
  • Have complications developed such as blood clots (thrombosis), heart attack (myocardial infarction), stroke, or heart failure? Has individual developed stomach (peptic) ulcer disease or gastric bleeding?
  • Has arthritis caused by deposits of uric acid in the joints (gout or hyperuricemia) occurred?
  • Has polycythemia vera converted to the condition where bone marrow is replaced with fibrous tissue (myelofibrosis)?
  • If complications have developed, what is the treatment and what are the expected outcomes with treatment?

Source: Medical Disability Advisor



References

Cited

Altman, Arnold J. "Polycythemia Vera." eMedicine. Eds. Sharada A. Sarnaik, et al. 31 Oct. 2002. Medscape. 18 Oct. 2004 <http://emedicine.com/ped/topic1850.htm>.

Source: Medical Disability Advisor






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