Knowing these two major functions of calcium helps explain why people can get a tingling sensation in their fingers or cramps in the muscles of their hands when calcium levels drop below normal. A sudden drop in the calcium level (which can occur following a thyroid surgery) can cause patients to feel "foggy", "weird" or "confused like my brain isn't working correctly". The brain DEMANDS a normal steady-state calcium level, so any change in the amount of calcium can cause the brain to feel un-loved and the patient to feel bad. Low calcium levels after thyroid surgery are also commonly associated with symptoms of tingling around the lips, hands, and/or feet. Cramping, facial twitching, or muscular spasms can also occur and may be more serious if not promptly treated.
Normal Parathyroid Activity / Normal Parathyroid Function
Although the four parathyroid glands are quite small, they have a very rich blood supply. This suits them well since they are required to monitor the calcium level in the blood 24 hours a day. As the blood filters through the parathyroid glands, they detect the amount of calcium present in the blood and react by making more or less parathyroid hormone (PTH). When the calcium level in the blood is too low, the cells of the parathyroids sense it and make more parathyroid hormone. Once the parathyroid hormone is released into the blood, it circulates to act in a number of places to increase the amount of calcium in the blood (like removing calcium from bones). When the calcium level in the blood is too high, the cells of the parathyroids make less parathyroid hormone (or stop making it altogether), thereby allowing calcium levels to decrease. This feed-back mechanism runs constantly, thereby maintaining calcium (and parathyroid hormone) in a very narrow "normal" range. In a normal person with normal parathyroid glands, their parathyroid glands will turn on and off dozens of times per day...in an attempt to keep the calcium level in the normal range so our brain and muscles function properly. Normal parathyroid function maintains nearly constant calcium levels... with almost zero variability. If the normal parathyroid glands are severely damaged or removed, they will not produce parathyroid hormone and calcium levels will drop. They can drop rapidly and place patients at serious risk of low calcium complications.
Normal parathyroid glands have quite predictable locations. When they are not in those predictable locations, we also know where they are most commonly located. Most normal parathyroid glands are quite tiny in the 4-6 mm range. Even though we already told you that parathyroid glands have a rich blood supply, the parathyroid glands don’t like it very much when we touch them during the thyroid surgery or have to move them out of the way.
The superior parathyroid glands are quite commonly tucked underneath the superior pole (upper part) of the thyroid and quite intimately attached to the capsule of the thyroid gland.
The inferior parathyroid glands are at greatest risk in thyroid cancer surgery when the lymph nodes of the central compartment are being removed. Parathyroid glands that are immediately adjacent to clearly cancerous lymph nodes should never be transplanted in thyroid cancer surgery. Parathyroid glands that don’t look healthy (they start looking brownish from decreased blood flow) following thyroidectomy or central compartment neck dissection should be transplanted whenever feasible. Any tissue that is being removed in thyroid cancer surgery should be closely examined for parathyroid tissue before it is sent to the pathologist for final analysis. Once tissue has left the operating room, it cannot be transplanted back into the patient!
Immediately following completion of your thyroid cancer surgery, the blood level of your parathyroid hormone produced by these glands can be measured to verify that your parathyroid gland (s) are meeting your body’s calcium regulation needs. You actually don’t need all of your parathyroid glands. In fact, most individuals can function totally normally with just one normal functioning parathyroid gland. But every one of your parathyroid glands should be managed as your only functioning gland. Each one of these parathyroid glands is critically important especially in thyroid cancer patients.