ALP (Alkaline Phosphatase)
Enzyme related to liver and bone health
20 of 22 providers
Liver Function
44-147 U/L
What is ALP (Alkaline Phosphatase)?
ALP (Alkaline Phosphatase) is an enzyme found primarily in your liver and bones, with smaller amounts in intestines, kidneys, and placenta (during pregnancy). ALP plays a role in breaking down proteins and is particularly concentrated in the bile ducts of the liver and in bone-forming cells (osteoblasts).
The challenge with ALP is determining the source:liver or bone. Elevated ALP from liver typically indicates cholestasis (bile duct obstruction or impaired bile flow), while bone-source ALP indicates increased bone turnover from growth, fracture healing, or bone disease. GGT is the key differentiator—if both ALP and GGT are elevated, the source is likely liver;if only ALP is elevated, consider bone disorders.
ALP can be mildly elevated in healthy growing children and adolescents due to bone growth, and during pregnancy due to placental ALP. In adults, persistently elevated ALP warrants investigation. Low ALP, though less common, can indicate nutritional deficiencies (zinc, magnesium, vitamin B6) or rare genetic conditions like hypophosphatasia.
Why ALP Is Your Bile Duct and Bone Health Sentinel
- Detects cholestasis:Elevated ALP with GGT indicates bile duct obstruction, primary biliary cholangitis, or drug-induced cholestasis before jaundice appears
- Bone disease screening:Isolated ALP elevation (normal GGT) suggests Paget's disease, osteomalacia, bone metastases, or hyperparathyroidism
- Early cancer detection:Markedly elevated ALP can indicate bone or liver metastases from various cancers
- Medication monitoring:Many drugs cause cholestatic liver injury with ALP elevation (antibiotics, antifungals, hormones)
- Nutritional status:Low ALP may indicate zinc, magnesium, or vitamin B6 deficiency, often overlooked
Optimal vs Standard Ranges
Optimal (Adult)35-100 U/L▼
- Optimal range for adults indicating healthy bile flow and normal bone turnover
- Values in this range suggest good liver and bone health, adequate nutrition, and low inflammation
- Note:Children and adolescents normally have higher ALP due to bone growth (can be 2-3x adult values)
Borderline High100-150 U/L▼
- Upper normal range;may warrant investigation depending on age and context
- Check GGT to determine if liver-related
- Consider bone source if isolated
- Retest in 3-6 months and investigate if rising trend
- Rule out benign causes (post-meal elevation in blood type O/B secretors, recent bone healing)
Moderately Elevated150-300 U/L▼
- Requires investigation
- If GGT also elevated:Evaluate for cholestatic liver disease, bile duct obstruction, primary biliary cholangitis, drug-induced liver injury
- Order liver ultrasound or MRCP
- If GGT normal:Consider bone disorders (Paget's disease, healing fracture, osteomalacia, vitamin D deficiency)
- Order bone-specific ALP isoenzyme, calcium, phosphate, PTH, vitamin D
Severely Elevated>300 U/L▼
- Indicates significant pathology requiring urgent workup
- Liver causes (with elevated GGT):Bile duct obstruction, primary sclerosing cholangitis, liver metastases, severe cholestatic drug reaction
- Order urgent imaging (ultrasound/MRCP)
- Bone causes (normal GGT):Paget's disease, bone metastases, osteomalacia, hyperparathyroidism
- Order bone scan, PTH, calcium, vitamin D
- Levels >1000 U/L suggest severe disease
Scientific Evidence
ALP and GGT for Differentiating Liver from Bone
Concurrent elevation of ALP and GGT has 94% specificity for hepatobiliary disease. If ALP is elevated with normal GGT, bone is the likely source. This simple combination effectively distinguishes liver from bone pathology without requiring expensive ALP isoenzyme fractionation in most cases.
ALP in Primary Biliary Cholangitis
In primary biliary cholangitis (PBC), ALP is often the first and most persistently elevated liver enzyme. Failure to normalize ALP with ursodeoxycholic acid treatment predicts worse prognosis. ALP >1.5x upper limit after 1 year of UDCA treatment is associated with increased risk of liver transplant or death.
Vitamin D Deficiency and ALP
Severe vitamin D deficiency causes osteomalacia (soft bones) with characteristic elevation of ALP, often 2-5x upper limit. Supplementation with adequate vitamin D (2000-4000 IU daily) normalizes ALP within 3-6 months. ALP can be used to monitor response to vitamin D therapy in deficient patients.
Source:Lips P. Vitamin D deficiency and secondary hyperparathyroidism in the elderly. Endocrinol Metab Clin North Am. 2001;30(4):833-843.
Low ALP and Mortality
Low ALP (<40 U/L) is associated with increased mortality risk in multiple populations, including heart failure patients and elderly individuals. Proposed mechanisms include nutritional deficiencies (zinc, magnesium), frailty, and impaired bone remodeling. Low ALP warrants nutritional assessment and supplementation.
Source:Beddhu S, et al. Associations of serum alkaline phosphatase with coronary artery calcification in CKD. Kidney Int Rep. 2018;3(6):1273-1281.
Paget's Disease and ALP
Paget's disease of bone causes dramatically elevated ALP, often 500-3000 U/L, reflecting increased bone turnover. Treatment with bisphosphonates reduces ALP by 50-80% and reduces bone pain and complications. ALP level correlates with disease activity and can be used to monitor treatment response.
Source:Singer FR, et al. Paget's disease of bone. J Bone Miner Res. 2014;29(10):2091-2098.
Which Providers Test ALP (Alkaline Phosphatase)?
Full Provider Comparison
| Provider | Includes | Annual Cost | Biomarkers |
|---|---|---|---|
 Superpower | ✓ | $199 | 100+ (150 with ratios) |
 WHOOP Advanced Labs | ✓ | $349 | 65 |
 Labcorp OnDemand | ✓ | $398 | 30+ |
| ✓ | $486 | 40+ | |
| ✓ | $444 | 288 | |
| ✓ | $349 | 100+ | |
| — | $761 | 54 | |
 Function Health | ✓ | $365 | 160+ |
| ✓ | $250 | 65 | |
| ✓ | $495 | 70+ | |
| ✓ | $895 | 100+ | |
| ✓ | $1950 | 150+ | |
| ✓ | $375 | 80+ | |
| — | $Varies | 75+ | |
| ✓ | $190 | 100+ | |
| ✓ | $99 | 50 | |
| ✓ | $124 | 60 | |
| ✓ | $199 | 50 | |
| ✓ | $499 | 120+ | |
| ✓ | $4188 | 70-80+ | |
| ✓ | $375 | 85 | |
| ✓ | $700 | 128 |
Frequently Asked Questions
What is ALP (Alkaline Phosphatase)?
Enzyme related to liver and bone health
What is the optimal range for ALP (Alkaline Phosphatase)?
The standard reference range for ALP (Alkaline Phosphatase) is 44-147 U/L. Optimal ranges may differ based on individual health goals and expert recommendations.
Which blood test providers include ALP (Alkaline Phosphatase)?
20 out of 22 blood testing providers include ALP (Alkaline Phosphatase) in their panels. This biomarker is widely available across major providers.
What category does ALP (Alkaline Phosphatase) fall under?
ALP (Alkaline Phosphatase) is categorized under Liver Function. This category includes biomarkers that help assess related aspects of health and wellness.
Medical Disclaimer
This information is for educational purposes only and is not medical advice. Always consult with a qualified healthcare provider about your specific health needs.
Last reviewed:2026-02-20