• Uncontrolled production of parathormone
It may be part of MEN (Multiple Endocrine Neoplasia)
MEN type I
•Pituitary adenoma &
•Pancreatic islet cell tumor
MEN type II
•Thyroid medullary carcinoma &
• Hyperplasia of the parathyroid in response
to decreased serum calcium level.
Causes of 2ry hyperparathyroidism:
• Renal osteodystrophy.
• Autonomous parathyroid nodule on top of
Action of parathormone hormone:
Increase serum calcium
Decrease serum phosphate
Ca re-absorption from renal Increase serum excretion
Ca absorption from the
1. Subperiosteal bone resorption
• Pathogonomonic for hyperparathyroidism.
• Lace like irregularity of the cortical margin progressing
to scalloping & spiculation (pseudo-periosteitis).
Radial aspects of the middle phalanges of the middle 3
Distal end of the clavicle
Medial tibial metaphysis.
Medial femoral neck
Medial humeral metaphysis
Superior & inferior margins of ribs.
2. Subchondral bone resorption
• Subchondral bone erosion, sclerosis with
narrowing of the joint space.
• DIP joint
(most commonly the ring & little fingers).
• MCP joint.
• Clavicular side of AC joint.
• Iliac side of SI joint.
Bowing of long bones.
Biconcave vertebral bodies.
PTH stimulation of osteoblasts.
Solid or lamellar.
Superior pubic ramus.
(osteitis fibrosa cystica)
• Replacement of bone by vascularized
fibrous tissue secondary to PTH
stimulated osteoclastic activity
• Expansile lytic lesion with well defined
non sclerotic margin.
They are usually eccentric