Hypoparathyroidism: Nursing

Hypoparathyroidism is a condition characterized by low blood parathyroid hormone, or PTH for short, which ultimately results in hypocalcemia, or low blood calcium levels, as well as hyperphosphatemia, or high blood phosphate levels.

Now, PTH is produced by four small glands called the parathyroid glands. These glands lie in the neck, being stuck to the back surface of the thyroid gland. The main function of PTH is keeping the levels of calcium within the normal range. For example, when calcium levels are low, PTH boosts bone resorption, which causes the release of calcium and phosphate from the bone into the bloodstream. In addition, PTH activates vitamin D, which in turn increases calcium and phosphate absorption from the gut. PTH also stimulates calcium reabsorption and phosphate excretion from the kidney. On the other hand, high calcium levels cause the secretion of PTH to fall, which increases the deposition of calcium in bones and the excretion of calcium by the kidneys.

Alright, now hypoparathyroidism can be caused by anything that damages the parathyroid glands. The most common cause is iatrogenic where surgery or radiation therapy for another condition also injures the parathyroid glands. Thyroidectomy is a good example since when a part of the thyroid is removed, the parathyroids will often be removed or damaged also. Hypoparathyroidism may also be caused by autoimmune destruction mediated by autoantibodies. Next, there are the functional causes like hypomagnesemia where the parathyroid glands will function poorly when magnesium level is low. However the glands are not damaged, so when hypomagnesemia is corrected, the hypoparathyroidism will resolve. Finally, hypoparathyroidism can be idiopathic, meaning that the cause is unknown.

Now, risk factors of developing hypoparathyroidism include neck surgery or radiation therapy; and serious injury to the neck, like during a car crash or by strangulation; as well as a family history of parathyroid disorder or autoimmune diseases.

Regardless of the underlying cause and type of hypoparathyroidism, when PTH levels fall below normal, they result in inhibition of bone resorption, as well as vitamin D activation, and calcium reabsorption from the kidneys. These changes add up to finally cause hypocalcemia, as well as hyperphosphatemia.

Now, many organs and tissues throughout the body depend on normal calcium levels to function properly. This is especially important in nerve transmission in the heart, muscles, and brain. As a result, hypocalcemia makes the neurons more excitable.

Okay, so in clients with hypoparathyroidism, signs and symptoms are typically associated with hypocalcemia. These can include photophobia, as well as mental status changes, which can range from anxiety, irritability, and confusion to psychosis, and in severe cases, even seizures. In addition, the increased neuromuscular excitability may result in tetany, which is characterized by involuntary muscle contractions leading to severe muscle cramps, most often involving the hands and feet, but severe cases can even involve the respiratory muscles, leading to difficulty breathing; clients with hypocalcemia can also present with paresthesia, or a feeling of tingling or numbness, typically around the mouth or in the hands and feet. In addition, hypocalcemia may lead to bronchospasm, laryngospasm, and even cardiac arrhythmias. Finally, hypocalcemia may manifest as two clinical signs; Chvostek sign and Trousseau sign. A positive Chvostek sign describes an ipsilateral contraction of facial muscles upon percussing the facial nerve; whereas a positive Trousseau sign describes an involuntary contraction of the muscles in the hand and wrist upon compressing the upper arm with a blood pressure cuff.

The diagnosis of hypoparathyroidism starts with history and physical assessment, followed by laboratory tests showing decreased blood levels of PTH, hypocalcemia, and hyperphosphatemia, as well as hypomagnesemia, and vitamin D deficiency, in addition to increased urine levels of cyclic adenosine monophosphate, or cAMP for short.