Differential diagnoses

Patients with hypophosphatasia (HPP) risk being incorrectly diagnosed, since the symptoms can overlap with those of many other, more common, diseases. Common misdiagnoses can be found in the table below.

Vitamin D deficiency	Osteomalacia
Hypophosphatemic rickets	Osteoporosis
Osteogenesis imperfecta (OI)	Periodontal disease
Skeletal dysplasia	Nephrocalcinosis
Neonatal hyperparathyroidism	Atypical/repeated/slow-healing fractures
Vitamin B₆-related seizures	Pseudogout
Chondrocalcinosis

In investigation and diagnosis of bone and/or mineral-related diseases, hypophosphatasia should be considered. Low activity of alkaline phosphatase (ALP) and high concentrations of ALP substrate differentiates hypophosphatasia from other diseases with similar symptoms. A simple blood test can make it easier to reach the right diagnosis.

HYPOPHOSPHATASIA (HPP) CAN BE DISTINGUISHED FROM OTHER DISEASES WITH SIMILAR SYMPTOMS BY ANALYSING LABORARTORY RESULTS
	Sjukdom
	Hypophosphatasia (HPP)	Rickets	Hypophosphatemic rickets	Osteogenesis imperfecta (OI)
Alkaline phosphatase (ALP)				Normal
Serum PLP		-		N/A
Calcium	or normal		Normal	Normal
Phosphate	or normal			Normal
Parathyroid hormone (PTH)	or normal		Normal	Normal
Vitamin D	Normal		or normal	Normal

Christov M & Jüppner H. Semin Nephrol. 2013; 33:143-57.
Elder CJ & Bishop NJ. Lancet. 2014; 383: 1665-76.
Faruqi T et al. Biomed Res Int. 2014; 2014:670842
Lee JY & Imel EA. Pediatr Endocrinol Rev. 2013; 10 Suppl 2:367-79.
Mornet E. Best Pract Res Clin Rheum 2008; 22: 113-127.
Rockman-Greenberg C. Ped Endocrinol Rev 2013; 10 (Suppl 2): 380-388.
Van Dijk FS & Sillence DO. Am J Med Genet 2014; 164A:1470–1481.
Warman ML et al. Am J Med Genet Part A 2011; 155: 943–968.
Whyte MP. Ann N Y Acad Sci 2010; 1192: 190-200.