Table 1.

Clinical Outpatient Laboratory Values

Lab reference range	Reference range	Laboratory results 4 y before referral	Laboratory results on referral
Alkaline phosphatase	31-125 U/L	27 (low)	23 (low)
Calcium	8.6-10.2 mg/dL	9.9	10
Phosphorus	2.5-4.5 mg/dL	…	4.3
Alkaline phosphatase, bone specific	5.3-19.5 mcg/L	…	4.8 (low)
Vitamin B6	2.1-21.7 ng/mL	…	24.4 (high)
Parathyroid hormone	14-64 pg/mL	41.30	…

Consistent laboratory results indicated hypophosphatasia because of low alkaline phosphatase and elevated vitamin B6 levels.