The parathyroid glands are four small glands located on the thyroid gland (see Figure 4.3). The primary function of the parathyroid glands is the regulation of calcium and phosphorus metabolism. Diagnosis of parathyroid disorders is based on an evaluation of serum calcium and serum phosphorus levels and 24-hour urine levels of calcium and phosphorus. The normal serum calcium level is approximately 8.5–10.5 mg/dl; the normal phosphorus level is about 2.5–4.5 mEq/L. Radioimmunoassay exams are used to check serum parathormone. Potential disorders of these glands include hypoparathyroidism and hyperparathyroidism.
Hypoparathyroidism is an inadequate production of parathormone and is most often related to the removal of the parathyroid glands during thyroid surgery. Parathyroid hormone (PTH) is responsible for the regulation of calcium and phosphorus levels in the blood. Calcium and phosphorus levels must be maintained within normal limits to have adequate nerve function. Bone density is also maintained by parathormone. Signs and symptoms of hypoparathyroidism include the following:
- Decreased blood calcium
- Increased blood phosphorus
- Neuromuscular hyperexcitability
- Carpopedal spasms (Trousseau’s sign)
- Positive Chvostek’s sign
- Urinary frequency
- Mood changes (depression)
- Dry, scaly skin and thin hair
- Changes in teeth (cavities)
- Changes in EKG (prolonged Q-T intervals and inverted T waves)
Management of the client with hypoparathyroidism involves the administration of IV calcium gluconate and long-term use of calcium salts. If calcium gluconate is administered intravenously, the rate should be monitored carefully because rapid administration can result in cardiac arrhythmias. Phosphate binders such as calcium acetate (Phoslo) can be used to bind with phosphates. This will result in a rise in the calcium level. Vitamin D supplements can be given to increase the absorption of calcium preparations as well as calcium in the diet.
Hyperparathyroidism is the direct opposite of hypoparathyroidism. In this disorder, you find an overproduction of parathormone. Signs and symptoms of hyperparathyroidism include
- Decreased blood phosphorus.
- Increased blood calcium.
- Muscle weakness.
- Bone pain and pathological fractures.
- Increased urinary output and renal calculi.
- Nausea and vomiting.
- Changes in EKG (shortened Q-T interval and signs of heart block). Heart block involves an alteration in the conduction system of the heart. In third- and fourth-degree heart block, there is an alteration in the heart’s ability to transmit electrical impulses from the sinus node located in the right atria to the ventricle. This interference in the conduction system can cause a prolonged P-R interval and possibly deletion of atrial contractions.
Managing a client with hyperparathyroidism is accomplished by the removal of the parathyroid. Preoperative management involves the reduction of calcium levels. Postoperative management includes
- Assessment of the client for respiratory distress
- Maintaining suction, oxygen, and a tracheostomy set at bedside
- Checking for bleeding (1–5ml is normal)
- Checking the serum calcium and serum phosphorus levels
To prevent the need for lifelong treatment with calcium, the client might have a parathyroid transplant—implantation of one or more parathyroid glands to another part of the body. If this is not possible, a total parathyroidectomy might be performed. If this is the situation, or if inadequate production of parathormone is found, the client will require lifelong supplementation with calcium and vitamin D.