Generalised Pruritus Systemic Causes
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Direct answer
Generalised pruritus without a primary rash is often a sign of systemic disease, most commonly cholestatic liver disease, chronic kidney disease, lymphoma, polycythaemia vera and iron deficiency. The approach is to check liver, kidney, blood and thyroid tests, since each cause leaves a characteristic abnormality. Itch triggered by warm water is a classic clue to polycythaemia vera.
What you must remember
- Cholestasis: primary biliary cholangitis, primary sclerosing cholangitis and obstructive jaundice raise alkaline phosphatase and bile acids, and are a classic cause of intense itch.
- Uraemia: pruritus in chronic kidney disease is driven by uraemic toxins and improves with adequate dialysis and, in some patients, phototherapy.
- Lymphoma: Hodgkin lymphoma classically presents with generalised itch that can precede lymph node enlargement by months.
- Polycythaemia vera: aquagenic pruritus, an itch provoked by contact with water and especially warm water, is a classic clue.
- Iron deficiency: pruritus can occur with iron deficiency and typically settles with iron replacement and treatment of the source of loss.
- Thyroid disease: both hyperthyroidism and hypothyroidism can cause pruritus, so TSH is checked in every workup.
- Drugs: opioids and cholestatic drugs cause pruritus, and a full drug history is part of the evaluation.
Matching the clue to the test
A 50-year-old woman has itched all over for three months, with no rash on examination. The table lists the systemic causes with their characteristic clues and first investigations.
| Cause | Characteristic clue | Key test | Main management |
|---|---|---|---|
| Cholestasis | Jaundice, dark urine, pale stools | Raised ALP and GGT, bile acids | Treat the biliary cause; cholestyramine for itch |
| Uraemia | Advanced chronic kidney disease | Raised urea and creatinine | Adequate dialysis, phototherapy |
| Lymphoma | Night sweats, weight loss, nodes | Node biopsy | Treat the lymphoma |
| Polycythaemia vera | Itch after a warm bath | Raised haemoglobin, JAK2 testing | Specialist-directed cytoreduction |
| Iron deficiency | Pallor, menorrhagia | Low ferritin | Oral iron and source control |
| Thyroid disease | Tremor, heat intolerance or slowed reflexes | TSH and free thyroxine | Treat the thyroid disorder |
Iron deficiency and cholestasis are common and easy to exclude, while lymphoma and polycythaemia need biopsy or a myeloproliferative work-up. A normal liver and kidney panel does not exclude a systemic cause, so the evaluation continues through blood counts, thyroid tests and imaging. Improvement of the itch once the suspected cause is treated is itself useful diagnostic evidence, and persistent itch after treatment prompts a broader search.
High-yield viva angles
Viva questions reward the link between a symptom and a specific test.
- Trap: treating generalised itch with antihistamines alone Correct: antihistamines give limited relief in systemic pruritus, so the underlying cause is sought first.
- Trap: assuming itch after bathing is atopic eczema Correct: aquagenic pruritus is a classic clue to polycythaemia vera, and a full blood count is needed.
- Trap: stopping the workup after a normal liver panel Correct: cholestasis is only one cause, and lymphoma, iron deficiency and thyroid disease also need excluding.
Frequently asked questions
Which blood test points to cholestasis as the cause of generalised itch?
Raised alkaline phosphatase and gamma-glutamyl transferase suggest cholestasis as the cause of generalised itch. Serum bile acids are often raised, and serum bilirubin may be normal early in the disease. Ultrasound of the liver and biliary tree is then used to exclude obstruction.
Why does polycythaemia vera cause itching after a bath?
Polycythaemia vera can cause aquagenic pruritus, an intense itch provoked by contact with water, especially warm water. A full blood count and JAK2 mutation testing help confirm polycythaemia vera in such patients. The itch is a symptom to link to the blood count rather than a rash to treat.
Is lymphoma a recognised cause of generalised pruritus?
Lymphoma is a recognised cause of generalised pruritus, particularly Hodgkin lymphoma, and the itch can precede lymph node enlargement by months. Pain at the nodes after alcohol intake is a classic but uncommon feature. Unexplained itch with fever, night sweats or weight loss needs a lymph node or imaging review.
How is uraemic pruritus treated?
Uraemic pruritus improves with adequate dialysis and, in some patients, with phototherapy or specific antipruritic medication. Emollients help symptomatically but do not treat the cause. Phosphate and parathyroid disorders are also addressed in dialysis patients with persistent itch.