Table 1.

Adapted from Smack et al. [3]

Classification	Main demographic	Familial patterns	Common Sites	Serum Electrolyte Level	Clinical Presentation
Primary Normophosphatemic TC	- Onset before 2nd decade (63%) - Mostly involve patients in tropical or subtropical regions - No sexual predilection	- Nil familial pattern	- Hip (31%) - Elbow (24%) - Knee (16%)	- Normal serum phosphate - Normal serum calcium	- Solitary calcification predominates (66%) - History of trauma - Milky fluid of calcification on incision are common
Primary Hyperphosphatemic TC	- Onset before 2nd decade (82%) - No sexual predilection - Higher frequency in blacks and men	- Strong familial pattern - Most patients are siblings (74%)	- Hip (37%) - Elbow (27%) - Shoulder (23%)	- Elevated serum phosphate - Elevated serum calcium	- Multiple calcifications predominate (74%) - Milky fluid of calcification on incision in all cases reviewed
Secondary TC	- Onset before 2nd decade (51%) - Higher frequency in whites and women - Chronic renal failure is the most common identifiable condition	- Some familial pattern	- Hip (29%) - Elbow (24%) - Shoulder (17%)	- Elevated serum calcium	- Multiple calcifications predominate (80%) - Milky fluid of calcification on incision in all cases reviewed