Bone specific alkaline phosphatase

The bone AP isoenzyme is an enzyme localised on the osteoblasts, and in adolescents also on the chondroblasts.

The active osteoblasts involved in the formation of new bone have a higher specific AP activity than osteozygotes. The specific activity of BAP in the bones of adolescents is 10 times higher than in adults.

The enzyme is not excreted via the kidneys and is therefore of differential diagnostic importance in patients with chronic kidney disease.

Material: 1 ml serum (determination by ELISA or IRMA).

Reference ranges of BAP (IRMA):

• women (premenopausal): 4.7 - 27.0 µg/l
• Women (postmenopausal): 5.5 - 27.1 µg/l;
• Men: 5,7 - 32,9 µg/l

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• Children m+w <10: 15-130 µg/l
• Children (m)<10: 15 - 130 µg/l
• Adolescents (m) 15-17: 30 - 70 µg/l
• Adolescents (m) 17-19: 15 - 50 µg/l

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• Children (w) 11-12: 25 - 150 µg/l
• Adolescents (w) 13-16: 5 - 55 µg/l
• Adolescents (w) 17-20: 2 - 30 µg/l

1. Neumeister B (2018) Thyroid hormones. In: Neumeister B et al. (Eds) Clinical guide to laboratory diagnostics. Elsevier GmbH S. 89