Vitamin B-12 is most commonly known for its role in food metabolism and its function in creating new red blood cells. Generally, your body excretes any excess vitamin B-12 you ingest, but certain diseases or disorders may lead to an overabundance of B-12 in your blood. If your doctor determines that you have abnormal B-12 serum levels, it may be a sign of a more serious condition.
Toxicity
As an adult, you should get 2.4 mcg of vitamin B-12 from your diet or supplements. Being pregnant ups your requirement to 2.6 mcg, but you need as much as 2.8 mcg while breastfeeding, the Linus Pauling Institute notes. Nearly all vitamins and minerals have a tolerable upper intake level, or UL, letting you know how much of the nutrient you can safely consume. There are no adverse effects with B-12, so it is not toxic at high doses in healthy adults. Since excess B-12 goes out in your urine, having an overabundance in your system may be a sign of chronic illness.
Elevated B-12 Levels
Having an overabundance of B-12 in your system is rare, so if you are at the higher end, it may make your doctor suspicious of a possible malfunctioning organ. Normally, your B-12 should fall between 200 and 900 pg/mL, according to MedlinePlus. Having B-12 serum at or below 200 mg may be a sign of a deficiency. If your B-12 level is around the 900 pg/mL mark, your doctor may run additional tests to determine an underlying cause.
Liver Problems
High B-12 serum levels may be a warning sign of problems with your liver. A malfunctioning liver may stem from alcoholism, genetics, poor diet or diabetes. Elevated B-12 can be a side effect of hepatitis, a disorder that causes swelling, inflammation and cell damage in your liver. Hepatitis C, if left untreated, often leads to cirrhosis, which is a serious form of chronic liver disease. Cirrhosis leads to irreversible scarring and makes your liver function poorly. In addition to elevated B-12 levels, you may have yellow-colored skin, pain in your abdomen, dark urine or blood in your stool if you have liver problems.
Cancer
Having an overabundance of B-12 in your system may also come from a certain type of cancer. Chronic myelogenous leukemia, or CML, is a form of cancer that affects bone marrow. CML causes cancer cells to grow from cells that produce white blood cells, thus severely weakening your immune system. Other warning signs of this type of leukemia include bruising easily, a swollen spleen, small pinpoint rashes and a chronic low-grade fever.
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