Initial Laboratory Workup for Generalized Pruritus Without Urticaria

Core Initial Laboratory Tests

The British Association of Dermatologists recommends that the initial laboratory workup for patients with generalized pruritus without urticaria should include full blood count, ferritin levels, liver function tests, and urea and electrolytes 1, 2
Full blood count and ferritin levels should be checked in all patients with chronic generalized pruritus without rash to evaluate for iron deficiency, which is a common cause of generalized pruritus 1, 3
Liver function tests should be performed to investigate for potential liver disease, especially cholestasis, which can cause generalized pruritus 1, 4
Urea and electrolytes should be checked to evaluate for renal disease, as uremic pruritus is a significant cause of generalized pruritus 1, 5

Blood film, lactate dehydrogenase, and erythrocyte sedimentation rate should be ordered if there is suspicion of hematological involvement 1, 6
JAK2 V617F mutation analysis should be considered if polycythemia vera is suspected, such as raised hemoglobin or hematocrit 5, 6
HIV and hepatitis A, B, and C serology should be considered, particularly with relevant risk factors or travel history 1, 4

For persistent unexplained pruritus, consider skin biopsy to rule out cutaneous lymphoma 4, 6
In patients with suspected iron deficiency and "normal" ferritin, consider checking serum iron and total iron binding capacity 3, 8

Ordering unnecessary thyroid function tests without clinical features suggesting thyroid disease 7
Failing to check ferritin levels, which is recommended in all cases of chronic generalized pruritus without rash 1, 3
Ordering extensive malignancy workups without specific clinical indicators 5
Not considering medication-induced pruritus, which requires a thorough medication review rather than specific laboratory tests 4