A study in India using 200 pg/ml as the blood level lower limit found 55% of hypothyroid patients were B12 deficient, whereas only 6.3% of Taiwanese patients were deficient with the same cut-off. An Israeli study found that 28% of their hypothyroid patients had B12 deficiency, but used the lower cut-off of 180 pg/ml, thereby potentially reporting an artificially low prevalence of B12 deficiency in their study group.

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October 6, 2020
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Numbness and Tingling Symptoms in Hypothyroidism May Be Due To Vitamin B12 Deficiency

Vitamin B12 deficiency is often associated with the most common form of hypothyroidism, autoimmune thyroid disease. In India, more than 50% of hypothyroid patients were found to be B12 deficient, but this is in a population with a much higher vegan/vegetarian diet compared to Taiwan that reported B12 deficiency in a little over 6% of those tested. The studies also don't always use the same laboratory cut-off levels for diagnosis, which is why the prevalence of B12 deficiency is reported over a wide range of 6.3% - 55%. Regardless of this, many experts in the field recommend screening for B12 deficiency in hypothyroid patients at diagnosis and periodically thereafter. People who have an under-active thyroid gland frequently complain of a variety of symptoms, but numbness, tingling and difficulty swallowing were most often reported by hypothyroid patients with vitamin B12 deficiency.

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Hypothyroidism, also called under-active thyroid, is when the thyroid gland doesn’t make enough thyroid hormones to meet your body’s needs. In regions where there is sufficient iodine, the most common cause of hypothyroidism is Autoimmune Thyroid Disease (AITD) - caused by antibodies that attack the thyroid gland and impairs thyroid hormone production. Thyroid hormones control the way the body uses energy, so they affect nearly every organ in your body, even the way your heart beats. Without enough thyroid hormones, many of your body’s functions slow down.

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Jonathan Bortz MD
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Jonathan’s background as a practicing diabetes specialist for 15 years and 17-year career developing nutritional prescriptive products for the pharmaceutical industry has contributed to his ability to understand nutrients, how they work and why they are important.

Over the years he has acquired broad and in-depth knowledge in minerals, essential fatty acids and other nutrients, but has special expertise in Vitamin B12 and choline metabolism. He is often asked to speak at national and international venues to articulate why B12, folate and choline are so important to gene function, brain development, liver and cardiovascular health. He applies pharmaceutical standards to nutrient science and has developed a unique ability to translate complicated concepts into simple promotional messages that resonate with practitioners and consumers. He has developed dozens of innovative nutritional products, of which many are category leaders in the US. Jonathan obtained his medical degree from the University of the Witwatersrand Medical School in South Africa and did his fellowship in Endocrinology at Washington University in St. Louis, MO.

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