Can blood work at a physical identify cancer? What causes a drop in B12?

Dr. Elaine Chin answers your health questions

Recently I experienced a rather severe episode with fatigue and muscle weakness. Tests revealed my B12 was very low. Since then I have discovered this fairly common. My question: What causes a drop in B12?Case, Aylmer, Ont.

B12 deficiency is much more common than we think. Recent research in our clinic showed that more than 30 per cent of our clients are functionally deficient for Vitamin B12.  This means the body does not have enough of this nutrient to function efficiently in many areas of metabolism, building proteins in the body, red blood cells, and normal function of nervous tissue.

Vitamin B12 deficiency often occurs as a combination of:
1)    Insufficient nutrient intake
2)    Poor absorption of B12 in the gut

This vitamin cannot be produced by the body. It is found in such foods as red meat, organ meats (liver), yogurt, dairy products, fish, clams, oysters, salmon and sardines. Some of these foods are high in cholesterol and are therefore not eaten regularly.

Some individuals lack a factor in their stomach necessary for absorption. This can result in anemia (low red blood count). You can prevent B12 deficiency by making sure you eat a variety of meat, dairy and fish regularly. Before embarking on taking B12 supplements simply because you are feeling tired, get a B12 blood test.  In our clinic we recommend the level be at least 350 pmol/L.

When my doctor prescribes a full blood test at my annual checkup, can this test indicate cancer? Does a full blood test check or have indicators for this? Daniel, Dorval, Que.

Unfortunately, the answer is likely no. Today’s traditional checkup blood test routine does not include the critical cancer specific markers. Typically, these routine tests assess for organ function. If such tests are found to be abnormal, they are neither specific nor precise for cancer.

The more common cancer screening markers—such as PSA (prostate cancer) and CA125 (ovarian cancer)—are not often offered by physicians because they are neither very accurate nor precise when trying to detect cancer. However, some physicians believe there is value in using these types of tests over time. They observe their “velocity of change”–the blood level rate of change year over year. If it changes dramatically, more investigations should be done to look for tumor growth. Specialty labs are able to provide tumor cancer markers for lung, liver, pancreas, colon and breast.

Genetic-based testing can tell an individual about their predisposition for certain types of cancer as well act as a tool for the early detection of cancer. This is the future of cancer screening. These tests are much more accurate than the older generation of cancer markers. They are available through physicians trained in the area of preventive genetics and who practice personalized medicine.

Send your questions for Dr. Elaine Chin, chief medical officer of the Scienta Health Group, to

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