Hypoparathyroidism after thyroid removal linked to kidney damage
Study urges research into improving identification, preservation of glands
Permanent hypoparathyroidism, which can occur when the parathyroid glands are accidentally removed along with the thyroid gland during a surgical procedure, increases the risk of kidney damage over time, according to a study by researchers in Hong Kong.
“Careful patient selection and improvement in the identification and preservation of parathyroid glands during surgery could reduce the risk of [hypoparathyroidism],” the researchers wrote. This, in turn, could reduce the risk of kidney complications.
The study, “Long-term kidney outcomes in patients with permanent hypoparathyroidism after total thyroidectomy for benign disease: A population-based study,” was published in Surgery.
Hypoparathyroidism can arise as a complication of total thyroidectomy, a surgery to remove the entire thyroid gland. Accidental removal of the neighboring parathyroid glands, which produce a calcium-regulating hormone, causes calcium levels to drop, leading to several symptoms.
“Careful identification and preservation of parathyroid glands during thyroidectomy is of utmost importance in preventing [hypoparathyroidism],” the researchers wrote. However, these glands are identified “mainly by their anatomical location and classical appearance with a yellowish color,” which can be challenging.
Calcium supplements and kidney function
Hypoparathyroidism requires patients to take oral calcium and vitamin D supplements for at least six months after surgery. However, too much calcium from supplements can build up in excess in the kidneys, leading to kidney stones. Whether this limits kidney function is unclear.
To know more about the impact on kidneys of postoperative permanent hypoparathyroidism, researchers analyzed data from 3,245 patients who underwent total thyroidectomy for benign disease from 1999 to 2014, focusing on their estimated glomerular filtration rate (eGFR), a measure of kidney function calculated based on creatinine, a waste product that is normally eliminated in the urine.
Of the 3,245 patients, 418 (12.9%) developed permanent hypoparathyroidism. Six months after total thyroidectomy, their median daily dose of calcium carbonate was three grams; that of calcitriol, the active form of vitamin D, was 0.5 micrograms. Of the patients with hypoparathyroidism, 368 (88%) required calcium and vitamin D supplements beyond one year after surgery.
After a median of 11.6 years of follow-up, a greater proportion of patients with the disease had a sustained decline in eGFR, by 50% or more, compared with those without hypoparathyroidism (15.6% vs. 6.9%), which translated into a 2.77 times higher risk of kidney function decline for patients with hypoparathyroidism.
Moreover, the decline in eGFR was more than twice as fast in patients with hypoparathyroidism.
There was no significant difference in the proportion of patients who progressed to end-stage kidney disease, which occurs when the kidneys stop functioning, but more patients with hypoparathyroidism required dialysis over time (1.2% vs. 0.4% in the group without the disease). None of the patients analyzed underwent a kidney transplant.
Besides hypoparathyroidism, other independent risk factors for eGFR decline included diabetes and a preoperative eGFR of less than 60 mL/min/1.73 m2.
Hypoparathyroidism after a total thyroidectomy “was associated with a higher risk of renal impairment over time,” the researchers wrote, adding that “kidney function and urinary calcium excretion should be closely monitored” in these patients.
“Further research is warranted to improve the identification and preservation of parathyroid glands during thyroidectomy,” the team wrote.
About the Author
