ALP (alkaline phosphatase) isoenzyme

Table of Contents

Alternative Names

Alkaline phosphatase isoenzyme test


Normal Values

The normal value is 20 to 140 IU/L (international units per liter). Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.

Adults have lower levels of ALP than children. Bones that are still growing produce higher levels of ALP. During some growth spurts, levels can be as high as 500 IU/L. For this reason, the test is usually not done in children, and abnormal results refer to adults.

The isoenzyme test results can reveal whether the increase is in "bone" ALP or "liver" ALP.


What abnormal results mean

Higher-than-normal ALP levels may indicate:

  • Pregnancy
  • Healing bone fracture
  • Liver diseases
  • Biliary obstruction
  • Hepatitis
  • Bone disease
  • Paget's disease
  • Osteoblastic bone tumors
  • Osteomalacia
  • Rickets
  • Skeletal disease
  • Anemia
  • Rickets
  • Leukemia
  • Thyroid gland inflammation
  • Hyperparathyroidism
  • Chronic alcohol ingestion

Lower-than-normal levels of ALP may indicate:

  • Protein deficiency
  • Magnesium deficiency
  • Too much vitamin D or too little vitamin C
  • Poor nutrition

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Review Date: 05/07/2009
Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School, Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org)