This is a prospective three-year natural history study of adults with hypoparathyroidism. The goal is to monitor patients with hypoparathyroidism to define end-organ damage in the context of the disease.

The study objectives are to:

1. Build a prospective cohort of patients to study HPT-associated end-organ damage.
2. Determine end-organ physiologic consequences of HPT.
3. Elucidate determinants of HPT-associated end-organ damage.

Funding Source - FDA OOPD

The goal of this study is to prospectively collect data on the natural history of hypoparathyroidism (HPT). This will enable longitudinal data collection of complications in this disease, specifically defining the epidemiology of end-organ complications of HPT that are related to high calcification propensity. It will also determine relationships between calcification burden and end-organ disease severity and progression risk and assess the utility of traditional and novel biomarkers of mineral and bone metabolism on disease diagnosis and monitoring. These data will inform future investigations on the development, study, and implementation of HPT end-organ disease modifying strategies and impact clinical practice in hypoparathyroidism.

Inclusion Criteria:

• An understanding, ability and willingness to fully comply with study procedures and restrictions.
• Ability to voluntarily provide written, signed and dated informed consent as applicable to participate in the study.
• Male or female ≥18 years of age with HPT. All HPT sub-types are eligible, including surgical (HPT-S) and nonsurgical (HPT-NS) HPT: autoimmune, genetic (including but not limited to: DiGeorge syndrome, autoimmune polyendocrine syndrome type 1, hypoparathyroidism sensorineural deafness and renal disease syndrome, Kearns-Sayre syndrome, mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes [MELAS] syndrome, mitochondrial trifunctional protein [MTP] deficiency syndrome, Kenny-Caffey syndrome, Sanjad-Sakati syndrome, autosomal dominant hypocalcemia), infiltrative (granulomatous), mineral deposition (copper, iron), metastatic, radiation and idiopathic HPT.
• Diagnosis of HPT established based on historic hypocalcemia in the setting of inappropriately low serum PTH levels on two occasions.
• All treatment regimens are permitted, including but not limited to conventional management with calcium (e.g. calcium citrate, calcium carbonate, etc), active vitamin D (calcitriol, alfacalcidol), parent vitamin D, magnesium, phosphate binders and thiazides. Use of PTH-like drugs are permitted.

Exclusion Criteria:

• Functional HPT
• Transient HPT
• Pseudohypoparathyroidism
• Pregnancy

Male or female ≥18 years of age with all hypoparathyroidism sub-types. Healthy male and female controls.