Stable Post-surgery Supplement Doses Can Take Months to Determine

Typically, it takes nearly three months before people newly diagnosed with chronic, post-surgical hypoparathyroidism arrive at a stable dose of calcium and vitamin D supplements, a study reported, rather than several weeks.

But many patients in this study also experienced abnormally high or low calcium levels even after a stable dose was set, highlighting the need for regular monitoring.

The study, “Changes in treatment needs for chronic postoperative hypoparathyroidism during initiation of conventional treatment compared to stable phase of treatment,” was published in the journal Endocrinology, Diabetes & Metabolism.

Hypoparathyroidism is characterized by abnormally low levels of calcium. As such, standard its management involves taking supplements of calcium and of vitamin D, which helps the body to absorb calcium.

Doses of these supplements often require adjustments to ensure that calcium levels within the body remain in a healthy range. However, there is little published data on how such adjustments tend to be experienced in the real world; some studies suggest that patients are usually able to find a stable dose in as little as a month.

Researchers in Denmark performed a retrospective review of hypoparathyroidism patients at their clinic, paying specific attention to supplement doses and body calcium levels  to understand how the process of arriving at a stable dose tends to play out.

They hypothesized “that the patients attain a stable phase of treatment with calcium and active vitamin D during the first month after surgery.”

Hypoparathyroidism is usually caused by neck or throat surgery that damages the parathyroid glands, or a surgery to remove these glands. Patients in this study were newly diagnosed with chronic hypoparathyroidism, meaning hypocalcemia — poor calcium absorption — caused by inadequate secretion of the parathyroid hormone lasting six months or more.

In all, the researchers reviewed records for 24 people with surgery-associated, chronic hypoparathyroidism. They ranged from 21 to 72 years old; 71% were women, and 29% were men.

After hypoparathyroidism was diagnosed, calcium supplements were generally given at a high dose (about 12 g/patient/week), with doses decreasing to about 6 g/patient/week after five to seven weeks, at which point they remained stable.

Meanwhile, most were also given increasing doses of vitamin D supplements (specifically, alfacalcidiol) for the first three weeks after surgery, with doses peaking at an average of 23 micrograms/patient/week. Vitamin D doses then tended to decrease, ultimately reaching a stable level — around 19 micrograms/patient/week — after about 11 weeks, or just under three months.

“Our data demonstrated that treatment needs varied greatly until 11 weeks after surgery, where the mean doses of alfacalcidol became more stable, which occurred a bit earlier for doses of calcium,” the researchers concluded.

The length of time needed to achieve a stable dose is much longer than that reported in earlier research, they noted.

“Hence, we reject our hypothesis that the patients attain a stable phase of treatment with calcium and active vitamin D as early as during the first month after surgery,” the researchers wrote.

Although doses overall were stable at 11 weeks, most required at least one dose adjustment. A majority, 20 of the 24 patients, also experienced hypocalcemia (abnormally low calcium levels) even when on a stable supplement regimen.

“Days with hypocalcaemia occurred randomly and were not only in the beginning of the treatment but also in the stable phase of treatment, although the number of patients experiencing hypocalcaemia decreased concurrently with the number of weeks after surgery,” the team wrote.

During the stable phase of treatment, 11 patients experienced hypercalcemia episodes — high calcium levels — that lasted between one and seven days each week, about the same length of time as before taking supplements.

These findings highlight the need to monitor calcium levels regularly, even in patients on stable doses of supplements, the researchers noted.

“It would be of interest to investigate the possibility of obtaining a steady state sooner” by intensifying the initial supplement doses given while patients are still hospitalized after surgery, and put on diets with “strict amounts of protein, fat, carbohydrate, calcium, phosphorus and sodium,” they added, noting that an earlier study reporting stable doses in about a month was in people hospitalized for two weeks after a hypoparathyroidism diagnosis.

Study limitations include its small size and retrospective design, according to the researchers.