Pathophysiology
Hypoparathyroidism Is Characterized by the Absence or Deficiency of Parathyroid Hormone1,2
PTH Under Normal Physiologic Conditions1
PTH regulates calcium and phosphate levels in the bones, kidneys, and intestines, and may affect cognition1
~70%
of the circulating PTH in healthy subjects is secreted in a continuous manner4,5
Pathophysiology of Hypoparathyroidism1,3
The absence or deficiency of PTH results in1,3,10:
- Inhibition of calcitriol (active vitamin D) synthesis in the kidneys
- Leading to the indirect effect of reduced calcium absorption in the intestines
- Disruption of calcium/phosphate balance
- Reduced physical functioning and well-being
Effects of Hypoparathyroidism on Renal Function6-8
- The renal dysfunction associated with hypoparathyroidism results in downstream complications, including hypocalcemia, hyperphosphatemia, and hypercalciuria1,6,7
PTH Deficiency Leads to Reduced Bone Turnover2
Control
Hypoparathyroidism
Reprinted from Arquivos Brasileiros de Endocrinologia e Metabologia, 54(2), Rubin MR, Bilezikian JP, Hypoparathyroidism: clinical features, skeletal microstructure and parathyroid hormone replacement, 220-226, Copyright 2010, with permission from Elsevier.
Micro-CT images of trabecular bone from a patient with hypoparathyroidism and a control subject: Note the higher trabecular bone volume, number, and thickness in the image labeled Hypoparathyroidism.9
PTH deficiency disrupts1,2:
- Physiological access to calcium reservoirs in the bone
- The regulation of osteoclast and osteoblast activity
- Bone remodeling, leading to hypermature bone that may be more prone to fractures
