The body brilliantly regulates biochemical processes through feedback mechanisms. The thyroid gland constantly monitors levels of several substances to ensure the body has all it needs to function. When levels drop, the thyroid tells the body to produce more. When levels are too high, the thyroid issues instructions to remove the excess from the body. In this manner, low levels of vitamin D impact the functioning of the thyroid.
Located in the neck just below the Adam's apple, the thyroid gland produces hormones that regulate many systems, including metabolism, growth and the balance of calcium. Vitamin D is produced in the skin as sunlight is absorbed. It may also be obtained in the diet, but natural food sources are limited, so the best sources are dairy products that have been fortified. Vitamin D serves several roles that ensure a healthy immune system and help regulate insulin and blood pressure. You must have an adequate amount of vitamin D for calcium to be absorbed and used by the body.
Thyroid and Vitamin D
The thyroid and vitamin D are connected by their shared role in calcium regulation. The thyroid has four smaller glands called the parathyroid glands that are responsible for maintaining calcium levels in the body. These levels are tightly controlled because, in addition to its role in bones, calcium is critical for vital functions such as nerve impulse transmission and muscle contraction. When calcium levels drop, the parathyroid glands release a hormone that stimulates the bones to release calcium, and that activates more vitamin D so that the calcium can be absorbed.
Vitamin D Deficiency
Insufficient vitamin D may cause a medical condition called secondary hyperparathyroidism. If you do not have enough vitamin D, or if you have an underlying medical condition that interferes with the body's ability to use vitamin D, then the calcium you consume will not be absorbed. The resulting low levels of calcium stimulate the parathyroids, which means the bones will release calcium. However, without vitamin D, that calcium can't be absorbed. This sets up an ongoing cycle in which low levels of vitamin D result in constant stimulation of the parathyroid glands, with calcium continuously being removed from the bones.
Symptoms
Symptoms may be mild or nonspecific, or you may not have any symptoms until low levels of calcium have existed long enough to result in damage. Lack of vitamin D that causes the parathyroid glands to overwork may cause bone deformities, broken bones or swollen joints.
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