01Principles and purposeThe professional or clinical skill and the decisions it supports.
ALP is present in liver and bone, and the label cholestatic becomes meaningful only after its origin and relationship to other analytes are considered. Hepatobiliary ALP release increases when bile ducts or canalicular membranes are stressed. GGT often rises in hepatic cholestasis and helps establish provenance, although alcohol, obesity and medicines can make it nonspecific. Calculate pattern using multiples of each laboratory upper limit rather than raw values.
Cholestasis may be extrahepatic, such as a common-duct stone, pancreatic mass or distal bile-duct stricture, or intrahepatic, such as primary biliary cholangitis, primary sclerosing cholangitis, drug injury, sepsis or infiltration. Ultrasound addresses dilatation and gross structure, not every microscopic or early duct process. The next test must resolve a defined uncertainty rather than merely add another image.
The BSG guideline emphasises context: compare earlier results, review the medical history and current illness, and do not infer clinical importance from size or duration alone. A modest cholestatic change with weight loss may be more consequential than a larger stable drug-related rise. Once abnormality is confirmed, an aetiological screen is appropriate even when it is mild; unexplained jaundice or possible malignancy accelerates the pathway.
Key points
- A cholestatic pattern means ALP predominates over ALT; use the laboratory upper limits rather than comparing raw numbers with different reference ranges.
- Confirm a hepatobiliary source with GGT and clinical context because bone disease, growth, pregnancy and healing fractures can raise ALP independently of bile flow.
- Review bilirubin, albumin, INR, full blood count, symptoms, medicines and previous results; the height of an isolated enzyme does not determine urgency by itself.
- Ultrasound is a practical structural start: duct dilatation directs assessment toward extrahepatic blockage, whereas a normal duct requires consideration of intrahepatic cholestasis and early obstruction.
- The BSG adult liver aetiology screen includes ultrasound, hepatitis B surface antigen, hepatitis C antibody with PCR if positive, autoantibodies, immunoglobulins, ferritin and transferrin saturation.
- Do not simply repeat an abnormal panel unless there is a clear, short-lived insult expected to resolve; otherwise investigate the cause regardless of magnitude or duration.
- Document the next decision: emergency drainage, cross-sectional imaging, medication withdrawal, specialist referral or a cause-specific liver assessment.
02Situations and prioritiesThe context, relevant information and actions that matter most.
ALP raised with GGT, conjugated bilirubin or compatible symptoms supports liver or bile-duct origin and justifies structural and aetiological assessment.
Raised ALP with normal GGT and no hepatic clues should prompt bone profile, vitamin D and relevant skeletal or physiological assessment rather than biliary imaging alone.
Jaundice, pale stool, dark urine and duct dilatation point toward mechanical blockage; pain and fever increase concern for a stone complicated by cholangitis.
Pruritus with nondilated ducts, autoimmune disease, inflammatory bowel disease or a recent drug exposure suggests small-duct, canalicular or immune cholestasis.
Progressive painless jaundice, weight loss and worsening conjugated bilirubin require urgent cancer-focused imaging and referral even if ALP elevation is only moderate.
03Assessment and interpretationHow to gather information, assess the situation and recognise uncertainty.
Consider the information, its meaning and its limitations before deciding what follows.
- 01
Complete liver blood-test panel - Why
- Define the relationship among bilirubin, ALT, ALP, GGT and albumin rather than interpreting ALP in isolation.
- Interpretation and limitations
- Express ALT and ALP relative to their upper limits; add INR in significant illness because albumin changes slowly and may reflect non-hepatic factors.
- 02
Previous results and medication timeline - Why
- Distinguish a new obstruction or drug exposure from a longstanding stable biochemical phenotype.
- Interpretation and limitations
- Record start, dose change and stop dates for antibiotics, anabolic agents, antiepileptics, supplements and cancer therapy; temporal association supports but does not prove causality.
- 03
Abdominal ultrasound - Why
- Assess duct calibre, gallstones, gallbladder, liver texture, masses and portal features without ionising radiation.
- Interpretation and limitations
- Dilated ducts support a mechanical level and usually lead to MRCP or contrast CT according to suspected cause; normal ducts leave intrahepatic and early obstructive disease open.
- 04
MRCP or pancreatic-protocol CT according to the suspected lesion - Why
- Map bile ducts or stage a suspected mass after ultrasound and clinical assessment identify the question.
- Interpretation and limitations
- MRCP maps duct anatomy without instrumentation. Suspected pancreatic cancer with obstructive jaundice requires pancreatic-protocol CT before elective drainage; if CT shows localised disease and cancer treatment is planned, NICE separately offers FDG-PET/CT for staging. Urgent infected-obstruction source control should not wait for elective staging.
- 05
Adult liver aetiology screen - Why
- Detect viral, autoimmune and iron-related disease when structural imaging does not fully explain cholestasis.
- Interpretation and limitations
- AMA with cholestatic tests supports PBC in the right setting; immunoglobulins and other autoantibodies need clinical interpretation, and negative screening does not close persistent unexplained disease.
- 06
Bone profile and vitamin D - Why
- Investigate a non-hepatic ALP source when GGT and the rest of the liver panel are normal.
- Interpretation and limitations
- Vitamin D deficiency, Paget disease, metastases, fracture healing and physiological states require targeted follow-up; do not assign origin from ALP alone.
04Worked approachesCases with ordered reasoning, an action and a check of the outcome.
01Worked case: interpret and act on cholestasisA result becomes useful when it changes the next testA 72-year-old with new pruritus and 5 kg weight loss has total bilirubin 116 micromol/L, conjugated bilirubin 101 micromol/L, ALP 612 U/L with upper limit 130, ALT 88 U/L with upper limit 45, GGT 740 U/L and INR 1.1; ultrasound shows dilated intrahepatic and extrahepatic ducts.+
- 1ALP is 612/130 = 4.7 times its upper limit and ALT is 88/45 = 2.0 times its upper limit. This is ALP predominance with a measured predominantly conjugated bilirubin rise; GGT supports a hepatobiliary source.
- 2Combine the progressive itch, weight loss and dilated ducts: an extrahepatic malignant obstruction is now more concerning than bone ALP or isolated intrahepatic drug injury.
- 3The patient is afebrile, stable and fit for investigation: obtain urgent pancreatic-protocol CT before elective duct drainage. It shows a 2.8 cm pancreatic-head mass without major-vessel involvement or distant disease. Because CT-localised pancreatic cancer is being considered for treatment, offer staging FDG-PET/CT under NICE NG85; this shows no nodal or distant metastatic focus.
- 4HPB review confirms resectability and satisfactory cardiopulmonary, nutritional and functional fitness. The patient chooses prompt pancreaticoduodenectomy without a preoperative stent because there is no cholangitis, intolerable symptom burden or treatment delay. Resection histology confirms adenocarcinoma with clear margins; by postoperative day ten bilirubin has fallen to 22 micromol/L and recovery permits an oncology referral.
02Nondilated ductsPursue small-duct and hepatic causesALP and GGT remain raised but ultrasound shows no extrahepatic duct dilatation.+
- 1Review medicines, alcohol, inflammatory illness, inflammatory bowel disease and autoimmune features alongside the full liver panel.
- 2Complete the adult liver aetiology screen, including AMA, other autoantibodies, immunoglobulins and viral markers.
- 3Use specialist-directed MRCP when PSC or a subtle proximal stricture remains plausible, recognising that normal ultrasound is not definitive.
- 4Verify that the responsible team reviews persistent unexplained abnormalities rather than arranging indefinite isolated repeats.
03Isolated ALP routeEstablish tissue originAn otherwise well adult has raised ALP, normal bilirubin, ALT and GGT, and no liver symptoms.+
- 1Repeat the full context, including pregnancy possibility, recent fracture, bone pain, medicines and previous ALP values.
- 2Request calcium, phosphate and vitamin D with targeted bone assessment rather than automatically labelling cholestasis.
- 3Investigate focal symptoms or unexplained persistence for metabolic or malignant bone disease as clinically indicated.
- 4Document the confirmed source or specialist plan; a normal GGT changes probability but is not a standalone final diagnosis.
05Feedback, follow-up and evidenceReview outcomes, seek feedback and identify what to improve.
- Follow bilirubin, ALP and ALT at an interval determined by the suspected mechanism; record symptoms and imaging findings alongside the graph.
- Add INR, albumin, platelets, creatinine and glucose when chronic or acute liver dysfunction is possible because enzymes do not measure global functional reserve.
- After withdrawing a suspected drug, document the exact stop date and expected review point; worsening jaundice or INR requires earlier specialist reassessment.
- After drainage, verify clinical improvement and falling obstruction markers while watching for fever, pain or a plateau that suggests incomplete drainage or stent dysfunction.
- For unresolved nondilated cholestasis, ensure named gastroenterology or hepatology ownership and a decision about MRCP, biopsy or disease-specific surveillance.
06Special situationsVariants, exceptions and circumstances that change the usual approach.
Use upper-limit ratios
An ALP of 300 and ALT of 180 cannot be compared directly; normalise each to its laboratory upper limit before naming the predominant pattern.
Dilatation answers one question
A widened duct supports obstruction but does not establish benignity, malignancy, infection or the safest route for drainage.
GGT supports origin
GGT helps distinguish hepatic from bone ALP, but alcohol, metabolic disease and enzyme-inducing drugs reduce its specificity for obstruction.
Albumin changes slowly
A normal albumin does not reassure against acute severe injury; INR, glucose and clinical trajectory are more time-sensitive functional signals.
Repeat with a purpose
A planned repeat after a clearly transient insult is different from delaying investigation of an unexplained persistent abnormality.
07Common pitfallsFrequent interpretation and management errors.
- 01
Describing every raised ALP as obstructive jaundice ignores bone and physiological sources and can trigger irrelevant invasive investigation.
- 02
Using enzyme magnitude alone to decide seriousness misses modest abnormalities linked to cancer and dramatic changes from reversible exposures.
- 03
Ordering ERCP merely to diagnose a stable cholestatic pattern exposes the patient to pancreatitis and infection before non-invasive anatomy is defined.
- 04
Assuming nondilated ducts exclude biliary disease misses early obstruction, PSC, hilar disease and intrahepatic cholestasis.
- 05
Repeating liver tests without an aetiological plan can create delay while a drug reaction, autoimmune disease or malignancy progresses.