Alkaline Phosphatase: Elevated and low levels


Understanding Alkaline Phosphatase Levels

Alkaline phosphatase (ALP) is an enzyme found throughout the body, particularly in the liver, bile ducts, and bone. Variations in ALP levels can indicate a range of health conditions, making it a crucial marker in clinical diagnostics. This article provides insights into the differential diagnosis associated with elevated and low ALP levels, the normal range, implications of isolated ALP elevation, and the various forms of ALP.

Elevated Alkaline Phosphatase: Differential Diagnosis

Elevated levels of alkaline phosphatase can be caused by a variety of conditions, primarily affecting the liver and bones. Key considerations for differential diagnosis include:

  • Liver Disorders: Conditions such as cholestasis, primary biliary cholangitis, hepatitis, and cirrhosis can lead to elevated ALP due to liver dysfunction or bile duct obstruction.
  • Bone Diseases: Increased bone turnover or growth, seen in diseases like Paget’s disease of bone, osteomalacia, and during periods of rapid growth in children, can result in higher ALP levels.
  • Cancer: Bone cancers or metastasis from other tumors to the bone can elevate ALP.
  • Pregnancy: Elevated ALP is common in late pregnancy due to placental secretion.

Low Alkaline Phosphatase: Causes and Concerns

While less common, low ALP levels can also indicate health issues:

  • Malnutrition and Deficiency: Deficiencies in zinc and magnesium, important cofactors for ALP, can reduce enzyme levels.
  • Genetic Disorders: Conditions such as hypophosphatasia affect the bone metabolism and result in abnormally low ALP.
  • Excessive Vitamin D Intake: Over-supplementation can sometimes suppress ALP production.

Normal Range of Alkaline Phosphatase

The normal range for ALP varies by age and sex, reflecting differences in bone growth and turnover. Typically, adults have lower levels than children. The normal range in adults generally lies between 30 to 120 units per liter, but these values can differ slightly depending on the laboratory standards.

Isolated Alkaline Phosphatase Elevation

Isolated elevation of ALP, where ALP is high but other liver enzymes like AST and ALT are normal, can pose a diagnostic challenge. This pattern might suggest:

  • Intrinsic Bone Disease: Such as early osteoporosis or osteomalacia.
  • Asymptomatic Liver Disease: Early stages of a liver condition that has not yet affected other enzymes.
  • Genetic Variations: Some individuals naturally exhibit higher levels of ALP without any underlying disease.

Different Forms of Alkaline Phosphatase

Alkaline phosphatase can exist in several different forms, depending on its source within the body:

  • Liver ALP: This form is elevated in cases of liver disease or bile duct obstruction.
  • Bone ALP: Elevated in conditions that affect bone turnover, such as Paget’s disease or bone healing.
  • Intestinal ALP: Mainly found in the lining of the intestines and can be elevated in certain gastrointestinal diseases.
  • Placental ALP: Elevated during pregnancy and derived from the placenta.
  • Isoenzymes: These are genetically determined variants of ALP that can also indicate specific tissue involvement.

For individuals experiencing unexplained changes in their ALP levels, consulting with a healthcare professional is crucial. If you have concerns about your ALP levels or need a thorough evaluation, consider reaching out to a healthcare professional. Dr. Christos Zavos, with extensive experience in gastroenterology and hepatology, can provide specialized insights and care tailored to your health needs.

For expert medical consultation or to discuss further diagnostic steps, contact Dr. Zavos directly. You can reach out through the contact form on his website,, call (+30)-6976596988 or (+30)-2311283833, or email Scheduling an appointment at his private office in Thessaloniki, Greece, can ensure you receive the best care for your concerns.

Last update: 22 April 2024, 10:15


Gastroenterologist - Hepatologist, Thessaloniki

PhD at Medical School, Aristotle University of Thessaloniki, Greece

PGDip at Universitair Medisch Centrum Utrecht, The Netherlands

Ex President, Hellenic H. pylori & Microbiota Study Group