ð Module Overview
Learning Objectives
On completion of this module, you will be able to:
- Define an "isolated" raised ALP.
- List the common physiological and pathological causes of a raised ALP.
- Use Gamma-GT (GGT) to differentiate between a liver and bone source of ALP.
- Describe the investigation pathway for an asymptomatic patient with a raised ALP.
- Recognise the key features of Paget's disease of the bone.
- Confidently advise a patient on the meaning and management of a mildly raised ALP.
What is an Isolated Raised ALP?
An isolated raised ALP is a common finding on routine blood tests. The term "isolated" is key - it means the other liver function tests (bilirubin, ALT, AST) and the serum calcium level are all normal.
It's important to remember that laboratory "normal" ranges cover 95% of the healthy population. This means that, by chance, 2.5% of completely healthy people will have a result above the upper limit of normal.
â Causes of a Raised ALP
A raised ALP can be physiological (normal) or pathological (due to a disease process).
| Physiological Causes | Pathological Causes |
|---|---|
|
Liver (Hepatic) Origin:
|
ð§ Investigation Pathway
The following pathway helps to rationalise the investigation of an asymptomatic adult with an isolated raised ALP.
Initial Finding:
Isolated Raised ALP
Isolated Raised ALP
Is the patient symptomatic?
(Bone pain, weight loss, abdo pain, jaundice etc.)
(Bone pain, weight loss, abdo pain, jaundice etc.)
YES: Investigate and treat cause as appropriate (specific pathway depends on symptoms)
NO (Asymptomatic):
Repeat ALP within 4 weeks. Check GGT, U&E, FBC, Calcium, TFTs.
Repeat ALP within 4 weeks. Check GGT, U&E, FBC, Calcium, TFTs.
Is ALP still raised AND GGT result?
GGT Raised (Suggests Liver Source)
1. Liver Ultrasound
2. Anti-mitochondrial Ab (AMA for PBC)
3. Consider other liver screens (e.g., viral hep)
4. Refer to Hepatology if indicated or ALP >1.5x ULN
1. Liver Ultrasound
2. Anti-mitochondrial Ab (AMA for PBC)
3. Consider other liver screens (e.g., viral hep)
4. Refer to Hepatology if indicated or ALP >1.5x ULN
GGT Normal (Suggests Bone Source)
1. Measure 25-OH Vitamin D
2. Consider Bone Profile (Calcium, Phosphate)
3. Consider PTH if calcium abnormal
4. Consider Bone Scan/X-rays if Paget's or Mets suspected
5. Manage Vit D deficiency / Refer if needed
1. Measure 25-OH Vitamin D
2. Consider Bone Profile (Calcium, Phosphate)
3. Consider PTH if calcium abnormal
4. Consider Bone Scan/X-rays if Paget's or Mets suspected
5. Manage Vit D deficiency / Refer if needed
If all investigations are normal...
ALP âĪ1.5x Upper Limit of Normal (ULN):
Reassure patient. Reassess in 6 months. Consider discharge if stable.
Reassure patient. Reassess in 6 months. Consider discharge if stable.
ALP >1.5x Upper Limit of Normal (ULN):
Refer routinely to relevant specialist (e.g., Hepatology if GGT was high, Endocrine/Rheum if bone source suspected) for further assessment (e.g., isoenzymes, biopsy).
Refer routinely to relevant specialist (e.g., Hepatology if GGT was high, Endocrine/Rheum if bone source suspected) for further assessment (e.g., isoenzymes, biopsy).
ðĶī Paget's Disease of the Bone
Paget's disease is an important differential for an isolated raised ALP, particularly in older adults (rare before 40, prevalence increases significantly after 55). The UK has the highest prevalence in the world.
Key Features of Paget's Disease
- Pathophysiology: A chronic condition of disordered and accelerated bone remodelling, localised to one or several bones. Osteoclasts become overactive and excessively large, leading to rapid bone resorption, followed by disorganised and structurally weakened new bone formation by osteoblasts.
- Presentation: Often asymptomatic (~70%) and found incidentally due to raised ALP. Can present with bone pain (often described as deep, aching, worse at rest/night), bone deformity (e.g., bowed legs [tibia/femur], enlarged skull), warmth over affected bone, pathological fractures, or secondary osteoarthritis in adjacent joints.
- Common sites: Pelvis, femur, spine, skull, tibia.
- Diagnosis:
- Raised ALP (often markedly elevated, >4x ULN in active disease), reflecting increased osteoblast activity.
- Normal serum calcium and phosphate.
- Characteristic appearance on X-rays (e.g., bone expansion, cortical thickening, mixed lytic/sclerotic lesions).
- Radionucleotide bone scans are very sensitive for showing the extent and metabolic activity of affected areas ('hot spots').
- Management: Not all patients require treatment. Indications include symptomatic bone pain, neurological complications, or preparation for orthopaedic surgery. Treatment involves potent antiresorptive therapy, primarily with intravenous bisphosphonates (e.g., a single infusion of zoledronic acid), to suppress the overactive osteoclasts and normalise bone turnover, often achieving remission for several years. Analgesia is also important.
ðŊ OSCE Preparation
Counselling a Patient with a Raised ALP
Scenario: Mr. Smith, a 60-year-old man, had a routine blood test that showed a raised ALP of 160 iu/L (normal range up to 130). All other results, including LFTs and calcium, are normal. He is asymptomatic and has come to the pharmacy looking worried after seeing the result online.
Key Counselling Steps:- Acknowledge & Contextualise: "Hello Mr Smith, thanks for coming in. I understand you've seen your recent blood test results online and you're worried about the alkaline phosphatase, or ALP, level being a bit high. It's very common to see a mild elevation like this on routine tests, and often it doesn't indicate anything serious."
- Explain What ALP is Simply: "ALP is just an enzyme, a type of protein, that's found in several parts of the body, but mainly in the cells lining the bile ducts in the liver and in our bone cells. A raised level can sometimes be a sign of increased activity in one of those two areas."
- Interpret 'Isolated': "The good news is that the rest of your liver tests and your calcium level are all perfectly normal. We call this an 'isolated' raised ALP, which makes serious liver problems much less likely."
- Outline the Plan (Repeat & GGT): "Because you are feeling well and the rest of the tests are normal, the standard first step, which your GP will likely arrange, is simply to repeat the blood test in about a month or so. This is just to see if the level stays up or if it was just a one-off blip. At the same time, they'll usually check another liver enzyme called GGT. The GGT test is really helpful because it helps us figure out if the ALP is more likely coming from your liver or your bones."
- Reassure & Manage Expectations: "In many cases with a mild rise like yours, the level either returns to normal on the repeat test, or we find out which area it's coming from and can investigate further if needed. Often, no specific cause is found, and we just monitor it. The plan is really to take it one step at a time, and that GGT test will give us much clearer information."
- Safety-Net: "The most important thing is that you're feeling well. Of course, if you were to develop any new symptoms between now and the repeat test â things like persistent bone pain, unexpected weight loss, yellowing of the skin or eyes, or significant tummy pain â you should definitely let your GP know straight away."
- Check Understanding: "Does that make sense? So the plan is likely a repeat test including GGT, and to let the doctor know if any new symptoms pop up."
â Bonus: Clinical Pharmacist Case Study
The Patient: Liver or Bone?
Patient Profile: Mrs. Jones, a 65-year-old woman, has an isolated raised ALP of 250 iu/L (ULN 130). This is confirmed on a repeat test 4 weeks later. She remains asymptomatic. Her other LFTs, calcium, U&Es, FBC, and TFTs are all normal. Her GP asks for your advice on the next steps.
Pharmacist's Assessment & Plan (SOAP Note Format)
- Subjective: Patient remains asymptomatic according to GP notes.
- Objective: Persistently raised isolated ALP (~1.9x upper limit of normal). Other LFTs, calcium, U&Es, FBC, TFTs normal.
- Assessment:
- Persistent Isolated Elevation Confirmed: The finding is not transient. The normal results for other LFTs and calcium confirm it is 'isolated'.
- Source is Unknown: The key next step is to differentiate between a hepatic (liver) or bony source.
- Need for GGT: Following the standard investigation pathway, the next test required is Gamma-GT (GGT).
- Consider physiological factors (less likely): Given age (65), pregnancy and adolescent growth are excluded. Statistical anomaly is possible but less likely with this degree of elevation.
- Plan:
- Recommend GGT Test: Advise the GP to request a GGT level if not already done with the repeat ALP.
- Outline Subsequent Pathways based on GGT result:
- If GGT is raised: This points strongly towards a liver source (e.g., cholestasis, PBC, infiltrative disease). Given the ALP is >1.5x ULN, recommend arranging a Liver Ultrasound Scan and checking Anti-Mitochondrial Antibodies (AMA) to screen for Primary Biliary Cholangitis. Consider routine referral to Hepatology based on these results or if ultrasound is abnormal.
- If GGT is normal: This points strongly towards a bone source. Recommend checking a 25-OH Vitamin D level (osteomalacia is common and treatable) and potentially a Bone Profile (Calcium, Phosphate - although initial calcium was normal, checking again with phosphate is reasonable). If Vitamin D is low, treat appropriately. If Vitamin D is normal and ALP remains significantly elevated, consider referral to Endocrinology or Rheumatology for assessment for Paget's disease or other rarer bone disorders (X-rays or bone scan may be considered by specialist).
- Documentation: Clearly document the advice given to the GP, including the rationale for requesting GGT and the two distinct pathways depending on its result.
â Test Your Knowledge
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