Canadian national hypoparathyroidism registry: an overview of hypoparathyroidism in Canada

To evaluate the epidemiology, presentation and management of hypoparathyroidism in Canada. Hypoparathyroidism is associated with significant morbidity and poor quality of life. We present baseline results from the Canadian National Hypoparathyroidism Registry, a prospective observational study evaluating hypoparathyroidism in Canada.

Our study enrolled 130 patients with hypoparathyroidism. Patients were followed every 6 months with clinical and lab assessments. We present baseline data in this manuscript.

Seventy percent (91/130) of patients had postsurgical hypoparathyroidism, 30% (39/130) of patients had nonsurgical hypoparathyroidism due to autoimmune, genetic or idiopathic causes, and a molecular diagnosis was confirmed in 11 of these 39 patients. Pseudohypoparathyroidism was confirmed in 4/39 patients, DiGeorge syndrome in 2/39 patients, Barakat syndrome with a mutation in the GATA3 gene in 1/39, and activating mutations of the CASR gene in 3/39 patients with nonsurgical hypoparathyroidism. Renal complications with nephrocalcinosis or nephrolithiasis were present in 27% (14/52) of patients with postsurgical disease and 17% (4/24) of patients with nonsurgical hypoparathyroidism. Basal ganglia calcification was noted on imaging in 15% (n = 5/34) of patients with postsurgical hypoparathyroidism and 37% (n = 7/19) of patients with nonsurgical hypoparathyroidism.

Hypercalciuria was more commonly seen in those with renal complications of nephrocalcinosis, nephrolithiasis or CKD, and hyperphosphatemia was more commonly seen in those with basal ganglia calcification. Hospitalization occurred in 28% of those with postsurgical hypoparathyroidism and 46% of those with nonsurgical hypoparathyroidism. Hypoparathyroidism is associated with significant morbidity. Effective strategies to reduce the short-and long-term complications of hypoparathyroidism need to be developed and evaluated.