If Calcium Dips After Thyroid Removal

Vitamin D levels before thyroidectomy not linked to declining calcium after procedure

/ Author:  / Reviewed by: Robert Carlson, M.D Beth Bolt, RPh

(RxWiki News) Some patients who've had their thyroid removed experience a drop in calcium, a mineral that strengthens bones. Whether that drop is linked to low levels of vitamin D, which helps the body absorb calcium, hasn't been clear.

A new study found no link between vitamin D levels before surgery to remove patients' thyroids and the decline in calcium levels that a fraction of patients experienced after those operations.

The authors of this study noted that their findings could help physicians decide whether people undergoing thyroidectomy (surgical removal of thyroid gland) also need to take vitamin D supplements.

"Ask your doctor about healthy levels of calcium and vitamin D."

Patrick Sheahan, MD, FRCSI, a head and neck surgeon at South Infirmary Victoria University Hospital in Cork, Ireland, was this study’s lead author.

For this investigation, Dr. Sheahan and his research team analyzed 121 patients who underwent thyroidectomy operations at South Infirmary from November 2009 through September 2012.

The researchers reviewed, among other things, tests of patients’ vitamin D and calcium levels and thyroid function before and after surgery. Excluded from the study were patients with extremely high amounts of calcium in their blood prior to surgery. Also excluded were patients with a specific thyroid problem that causes the bones to lose calcium and, consequently, weaken.

These researchers concluded that 29 (24 percent) of the 121 patients had declines in calcium following surgery, a condition called transient biochemical hypocalcemia.

“The findings of our study suggest that … vitamin D levels [before surgery] do not have any significant effect on the incidence of … hypocalcemia [after surgery]."

They added, “At our institution … most patients undergoing thyroidectomy have undergone testing for vitamin D levels along with [parathyroid hormone] in the early postoperative period in an effort to predict the course of postoperative hypocalcemia and the requirement for vitamin D and calcium replacement.”

Low levels of parathyroid hormone (PTH) — just one of the hormones created by the thyroid gland — prevent the body’s organs and bones from properly absorbing, reabsorbing or releasing calcium.

Vitamin D also plays a key role in helping the body maintain the right calcium levels. 

These researchers cited prior studies showing that patients undergoing partial thyroidectomies were automatically given calcium carbonate and cholecalciferol, two forms of vitamin D.

The current findings do not mean that vitamin D supplements are always unnecessary for thyroidectomy patients, the researchers noted.

These researchers also wrote that more research is required before patients' possible need for those supplements can be confirmed.

Lack of adequate nutrition and lack of exposure to sunlight, which helps the body create vitamin D, is one of the reasons that many people in the United States and elsewhere are deficient in vitamin D, these researchers wrote.

According to the latest data available from the US Centers for Disease Control and Prevention (CDC), two thirds of the US population has enough vitamin D. The risks of not getting enough vitamin D are highest among black people and others whose darker skin pigmentation keeps their body from absorbing enough vitamin D-producing sun rays.

This study was published online February 27 in JAMA.

These researchers reported no financial investments or other involvements that would shape the study's design, analysis or outcomes.

Dr. Sheahan had open access to these medical records.

Review Date: 
February 27, 2014
Last Updated:
March 2, 2014