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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.

Vitamin B12 Deficiency


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Overview

Vitamin B12 deficiency is a nutritional disorder caused by either a lack of this vitamin in the diet or by the body's inability to use it. Cobalamin are compounds found in nature which contain the nucleus of vitamin B12.

Vitamin B12 has many important functions. It is required for the formation and regeneration of red blood cells, it has an important role in maintaining a healthy nervous system, it is required for proper digestion, it aids in the absorption of calcium, and it promotes growth in children. Vitamin B12 is mostly produced by animals, so we need to eat animal products (e.g., meat, dairy products, poultry, fish) to get enough of this vitamin in our diets. Vegetarians can obtain small quantities of vitamin B12 from consuming legumes (e.g., green beans, peas). In the stomach, acid and enzymes separate the vitamin from the proteins that carry it. The free vitamin is then passed into the small intestine and absorbed into the bloodstream. Some is used immediately, and some is stored in the liver or bone marrow.

Vitamin B12 deficiency has two possible causes. The most obvious cause is a diet that lacks a sufficient amount of this vitamin. Because vitamin B12 is abundant in a wide variety of readily available foods, this type of dietary deficiency is not very common. In fact, it generally only occurs in strict vegetarians (often referred to as vegans) who do not eat meats, dairy products, eggs, or fish. In addition, alcoholics and individuals with eating disorders such as anorexia nervosa or bulimia nervosa tend to have inadequate diets, which put them at risk for this vitamin deficiency.

The other cause of vitamin B12 deficiency is the body's inability to use the vitamin once it has been ingested. As described above, this vitamin must be processed in the stomach before it can be utilized. It also has to be absorbed in the small intestine so that it can enter the bloodstream. If the stomach does not produce enough of the required acid or enzymes, or if the small intestine does not absorb the nutrient, a deficiency will result. Diseases of the small intestine such as Crohn's disease, or surgical removal of a portion of the small intestine, can result in too little of the vitamin being absorbed. Certain medications such as colchicine (used to treat gout), phenytoin (used to treat seizures), metformin (for treatment of diabetes) may interfere with vitamin B12 absorption, as do acid-reducing drugs that are used to treat ulcers. Excessive alcohol consumption can impair vitamin B12 absorption, and individuals with AIDS also have trouble absorbing this nutrient.

Additional causes include stomach surgery, diseases of the pancreas, overgrowth of bacteria in the gastrointestinal tract, or the presence of a fish tapeworm. As we age, our stomachs produce less acid, so less vitamin B12 is freed from its carrier protein, and less is available for absorption. Thus, elderly people are at increased risk for this condition. A disease called pernicious anemia can also lead to vitamin B12 deficiency. Pernicious anemia is associated with the deficiency of a substance called intrinsic factor. Intrinsic factor is produced in the stomach, and used in the small intestine for absorbing vitamin B12. Mean age of onset for PA is 50 years in blacks, and 60 years in the white population (Diamond). Congenital deficiencies in transport-protein can lead to vitamin B12 deficiency as well.

Incidence and Prevalence: While the precise prevalence of vitamin B12 deficiency is not known, it is estimated to affect anywhere between 300,000 to 3 million individuals in US (Diamond). Some studies suggest that general population is affected with an incidence of 3% to 40% (Dharmarajan 99). One study found evidence of vitamin B12 deficiency in about 15% of elderly persons over 65 years (Pennypacker 1197). The prevalence of cobalamin deficiency in Europe is 1.6% to10% (Diamond).

Source: Medical Disability Advisor