Managing Hypoparathyroidism to Assure Optimal Clinical Care

American Thyroid Association Statement offers recommendations for clinical management of hypoparathyroidism following thyroid surgery.

With Victor J. Bernet, MD, and Thomas Fahey, MD

Following bilateral thyroid surgery, strategies to prevent the development of and minimize the risk for hypoparathyroidism (HypoPT), the most common post-surgical complication remains a critical diagnostic necessity.1 As such, endocrinologists and primary care practitioners (PCPs), who will be managing these patients, both before and after the surgery, have important roles to play in providing optimal care.

To better define the strategies available for early detection and management of hypoparathyroidism, the American Thyroid Association (ATA) Surgical Affairs Committee has issued a statement with important insights for patient management, 1 which was published in the journal Thyroid.

Monitoring for symptoms of hypocalcemia and low vitamin D before thyroid surgery improves outcomes.

This statement differs from official guidelines, said Victor J. Bernet, MD, FACP, FACE, chair of the division of endocrinology at Mayo Clinic, and associate professor at Mayo Clinic College of Medicine, in Jacksonville, Florida, and a coauthor of the ATA statement. He said, "A statement is meant to provide a summary of information and the state of the knowledge as we know it, without evidence-based recommendations." The committee considered the topic of sufficient interest to its association members, to gather and report on the available evidence for the benefit of endocrinologists, PCPs, and thyroid surgeons.

Here, Dr. Bernet and coauthor, Thomas J. Fahey III, MD, the Johnson and Johnson Professor and chief of endocrine surgery, at the New York Presbyterian Hospital—Cornell Medical Center, provided highlights of the most valuable information for physicians to consider.

Dr. Fahey offered this overall perspective to EndocrineWeb: "While hypoparathyroidism is the most common complication after bilateral thyroidectomy, permanent hypoparathyroidism is still fortunately very uncommon with a zero to 3% incidence." And estimates of temporary HPT range from about 19% to 38%.

For clinicians caring for patients prior to hypoparathyroid surgery, a very important point is to be sure the patients’ vitamin D levels are in the desired ranges beforehand, Dr. Bernet said, and the recommendations in the statement have specific advice on steps to address a low vitamin D status.1

Beyond those points, Dr. Bernet and Dr. Fahey share some practical management advice with EndocrineWeb, defining those at greatest risk and terminology

Defining Hypoparathyroidism and Concomitant Risk Factors

Hypoparathyroidism is defined as a condition in which a decreased secretion of PTH is accompanied by hypocalcemia and hyperphosphatemia.

Based on the ATA Surgical Affairs statement,1 risk factors for post-operative HypoPT are:

  • Simultaneous or sequential bilateral thyroid surgery
  • Autoimmune thyroid conditions, such as Graves' disease or chronic lymphocytic thyroiditis
  • Prophylactic or therapeutic central neck dissection
  • Substernal goiter
  • Surgery handled  by a someone with a low volume of thyroid procedures
  • Prior gastric bypass procedure, or another malabsorptive state
  • Thyroidectomy and parathyroidectomy, done simultaneously
  • ·History of central neck surgery

The fragile nature of the parathyroid glands, along with the short half-life (3 to 5 minutes) of PTH can set the stage for damage following any procedure but most often thyroid surgery, according to Dr. Bernet. In particular, clinicians should be familiar with four factors that may warrant intervention for hypoPT:

  • Hypocalcemia, a total serum calcium level less than the lower limit of the center-specific range.2 However, transient values outside normal ranges may reflect a state of hydration, rather than true hypocalcemia. While hypocalcemia may be present without hypoparathyroidism, untreated hypoPT will always lead to hypocalcemia, with a lag time of just hours to days.
  • An indication of biochemical hypoPT is a low intact PTH level, following below the laboratory standard lower limit, which is typically 12 ug/mL with hypocalcemia
  • Parathyroid insufficiency, also known as relative hypoPT, which may occur after central neck surgery.
  • Transient or temporary hypoPT may arise and last for no more than six months postsurgery; permanent hypoparathyroidism would be diagnosed when it persists beyond six months.2,3

Recognizing Symptoms and Warning Signs of Hypoparathyroidism

Among the earliest symptoms of hypoPT are hypocalcemia and paresthesia of the perioral region, muscle spasms, and cramps. Acute hypocalcemia may lead to increased neuromuscular irritability, followed by numbness.4 Changes in the patient’s mental state including confusion, anger, depression, and complaints of lightheadedness may occur and are most often noticed by a family member, friend, or caretaker. Over time, other symptoms may arise such as laryngospasm and seizures.

Tetany, observed or elicited, is another common sign of hypocalcemia. A positive Chvostek or Trousseau sign are also indicative of low serum calcium. Prolongation of the QT interval that may result in Torsades de pointes, a form of tachycardia, is a cardiovascular signal of depressed circulating calcium.

Strategies to Prevention Hypoparathyroidism

If a patient is scheduled for a bilateral thyroid procedure, initiating preoperative testing for baseline serum calcium, parathyroid hormone, and 25-hydroxy vitamin D blood levels is advised. The endocrinologist or PCP might initiate contact with the thyroid surgeon to determine who will be handling the blood work and evaluation. If the patient’s serum calcium is low normal, prescribing oral calcium supplementation is advised; if the serum calcium level is elevated, PTH should be measured to look for occult primary hyperparathyroidism.1

For preoperative vitamin D deficiency treatment, a regimen of 50,000 IUs of vitamin D3 weekly or 6,000 IUs daily for 8 weeks is recommended.

"Everyone gets so busy, they don't think about these useful prophylactic actions," Dr. Bernet said. After all, if found, a vitamin D deficiency would be easily corrected in the period leading to the surgery date. "It might take three to four weeks for thyroid surgery to be scheduled. At least you would have a head start to get the patient on high dose supplementation of vitamin D."

The other risk reduction strategy Dr. Bernet recommended is to refer patients to a high-volume thyroid surgeon—generally one who does at least 30 to 50 procedures a year. Doing so is the simplest and surest way to reduce the risk for any complications, he said.

Communicating between providers is also important, especially if the hypoPT becomes prolonged (permanent).

Another high-risk group—patients who have undergone bariatric surgery—should be watched closely, according to both experts. "Patients who have had a gastric bypass procedure may be particularly difficult to manage postoperatively [for thyroid surgery] due to a decreased ability to absorb calcium," Dr. Fahey told EndocrineWeb.

Tracking and Managing Postoperative Parathyroid Hormone

The ATA statement on management of hypoparathyroidism contains a recommendation to assess PTH levels in the immediate postop period,1 as the numbers may be useful to predict which patients are most likely to develop hypocalcemia and thereby inform follow-up and need for further management.

Based on their review of the literature,5-7 the committee concurred that a PTH at or above 15 ug/mL in adults at 20 minutes or longer after thyroidectomy would negate the need for intensive blood calcium monitoring or supplementation; a PTH level below 15 ug/mL would suggest an increased risk for acute hypoPT that might prompt preemptive prescribing of oral calcium and calcitriol and/or a serum calcium measurement until stability is achieved.

For patients undergoing thyroid surgery, a comprehensive review of post-operative management of hypoparathyroidism is available in Table 1, adapted from the ATA statement.

Overview of American Thyroid Association approach to optimal care following thyroid surgery.

Physicians should remember that long-standing HypoPT may impact quality of life significantly, the statement says, underscoring the need to minimize risks.

Neither Dr. Bernet nor Dr. Fahey report any relevant disclosures.

Continue Reading:
Safety of Thyroid Surgery in Older Adults
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