Yes, ALP and Alk Phos Are the Same Laboratory Test
ALP (Alkaline Phosphatase) and "alk phos" are identical—both refer to the same enzyme measured on standard laboratory panels. 1, 2 These are simply different abbreviations used interchangeably in clinical practice for alkaline phosphatase.
Understanding the Terminology
- ALP is the standard medical abbreviation for alkaline phosphatase, while "alk phos" is an informal shorthand commonly used in clinical settings 1
- Both terms refer to a membrane-bound metalloenzyme that exists as multiple isoenzymes encoded by at least four different gene loci: tissue-nonspecific, intestinal, placental, and germ-cell ALP 3
- The tissue-nonspecific gene produces the bone and liver isoforms through posttranslational modifications, which are the most clinically relevant sources 3
Clinical Significance of ALP Measurement
- ALP is produced in multiple tissues including liver, bone, intestines, kidneys, and placenta, with liver and bone being the predominant sources in adults 4
- When interpreting elevated ALP levels, measuring gamma-glutamyl transferase (GGT) concurrently helps determine the source—elevated GGT confirms hepatobiliary origin, while normal GGT suggests bone or other non-hepatic sources 2, 4
- ALP isoenzyme fractionation can determine the percentage derived from liver versus bone when the source remains unclear 2
Common Clinical Contexts
- In hepatobiliary disease, ALP elevation ≥2× upper limit of normal (particularly with elevated GGT) suggests cholestatic liver injury or biliary obstruction 1
- In bone disorders, ALP elevation with normal GGT indicates bone pathology such as Paget's disease, bone metastases, or fractures 2, 4
- Physiologic elevation occurs in childhood due to bone growth and in pregnancy due to placental production, reaching up to twice the upper limit of normal 2, 5