Calcification of the Basal Ganglia Identified in Patients With Hypothyroidism

Researchers writing in The Journal of Clinical Endocrinology & Metabolism report that basal ganglia calcification of the brain in patients with chronic hypoparathyroidism, may determine the severity of disease in patients with chronic hypoparathyroidism.

Also known as Fahr syndrome, basal ganglia calcification can occur in hypoparathyroidism as a result of a chronic build-up of calcium pyrophosphate crystals, which is the same process that can lead to arthritis. Symptoms in affected patients can include confusion, amnesia, and decreased attention span. The condition, although rare, and can disproportionately affect patients with hypoparathyroidism because it is associated with low serum calcium, increased serum phosphorus, and low or decreased serum parathyroid hormone, which may be associated with soft tissue calcification in the basal ganglia of the brain.

In this study, which was led by Bart L. Clarke, MD, of Mayo Clinic, Minnesota, researchers assessed the prevalence and factors involved in the pathophysiology of basal ganglia calcification in the brain of 142 patients with chronic hypoparathyroidism.

CT scans, which were conducted over a 20-year period between January 1, 2000, and July 9, 2020, revealed that 25.4% of patients with hypothyroidism had basal ganglia calcification in the brain compared to 7% of controls. Apparently, the condition is most often developed at younger ages. Surgery status was found to be an important factor in the presence of basal ganglia calcification (BGC). It was found to be 5.1-fold more common in nonsurgical patients, and less common in postsurgical patients.

“The ages of the patients with or without BGC were significantly different, suggesting that neurological complications may develop at a younger age in patients with BGC. These findings also imply that patients might be less likely to develop these complications as they become older. Most patients with chronic hypoparathyroidism were postsurgical, with significantly lower volume of calcification compared to those with nonsurgical hypoparathyroidism. The clinical impact of BGC on neurological diagnoses in patients with nonsurgical hypoparathyroidism remains to be fully elucidated,” the study authors wrote.

Researchers found wide variations in the extent of basal ganglia calcification in the patients, but there was a greater volume in the distribution of calcification among patients who did not undergo surgery. The ratio of both low serum calcium and low calcium/phosphate correlated with basal ganglia calcification. However, the presence of serum phosphorus or calcium x phosphate alone did not predict basal ganglia calcification. But for patients with lower serum calcium concentrations, they had a greater volume of basal ganglia calcification.

“The ages of the patients with or without BGC were significantly different, suggesting that neurological complications may develop at a younger age in patients with BGC. These findings also imply that patients might be less likely to develop these complications as they become older. Most patients with chronic hypoparathyroidism were postsurgical, with significantly lower volume of calcification compared to those with nonsurgical hypoparathyroidism. The clinical impact of BGC on neurological diagnoses in patients with nonsurgical hypoparathyroidism remains to be fully elucidated,” the study authors noted.

The researchers highlighted some study limitations, including the retrospective nature of the study, real-world data collection in patients followed clinically, relatively small numbers of subsets of patients, and single institutional referral bias.

Disclosures:  Dr Clarke has received institutional research funding from Takeda/Shire, Ascendis, and Chugai Pharmaceuticals for clinical trials in patients with chronic hypoparathyroidism.

Reference

Zavatta G, Tebben PJ, McCollough CH, Yu L, Vrieze T, Clarke BL. Basal ganglia calcification is associated with local and systemic metabolic mechanisms in adult hypoparathyroidism. J Clin Endocrinol Diabetes. Published online March 31, 2021. doi.org/10.1210/clinem/dgab162