From the Guidelines
For itching without a rash, investigations should begin with a thorough medical history and physical examination to identify potential causes, and initial blood tests should include complete blood count, liver function tests, kidney function tests, thyroid function tests, and blood glucose levels, as recommended by the British Association of Dermatologists' guidelines for the investigation and management of generalized pruritus in adults without an underlying dermatosis, 2018 1.
Initial Investigations
Initial investigations should focus on identifying common causes of generalized pruritus, such as:
- Anemia
- Liver disease
- Kidney disease
- Thyroid disorders
- Diabetes Additional tests may include:
- Serum ferritin to check for iron deficiency
- Erythrocyte sedimentation rate or C-reactive protein to detect inflammation
- Specific tests for cholestasis, such as alkaline phosphatase and bilirubin levels
Further Investigations
If the initial investigations do not reveal a cause, further tests may be necessary, including:
- Chest X-ray
- Abdominal ultrasound
- Specific tests for HIV, hepatitis B and C, or parasitic infections
- Skin biopsy to rule out microscopic skin conditions
Medication-Induced Itching
If medication-induced itching is suspected, a careful review of all current medications is essential, as recommended by the British Association of Dermatologists' guidelines for the investigation and management of generalized pruritus in adults without an underlying dermatosis, 2018 1.
Haematological Conditions
Haematological conditions, such as polycythaemia vera (PV), should be considered in the initial work-up of a patient with pruritus, and investigations should include full blood count, blood film, lactate dehydrogenase, and ESR, as well as testing for the JAK2 V617F mutation, as recommended by the British Association of Dermatologists' guidelines for the investigation and management of generalized pruritus in adults without an underlying dermatosis, 2018 1.
From the Research
Investigations for Itching with No Rash
When a patient presents with itching and no visible rash, it is essential to conduct a thorough investigation to determine the underlying cause. The following are some potential investigations to consider:
- A complete blood count with differential, creatinine and blood urea nitrogen levels, liver function tests, iron studies, fasting glucose or A1C level, and a thyroid-stimulating hormone test, as suggested by 2
- Additional testing, including erythrocyte sedimentation rate, HIV screening, hepatitis serologies, and chest radiography, may also be appropriate based on the history and physical examination, as noted by 2
- Evaluation for malignancy in older patients with chronic generalized pruritus, as recommended by 2
- Assessment of exposure history to reveal potential symptom triggers, as mentioned by 3
- A thorough skin examination, including visualization of the finger webs, anogenital region, nails, and scalp, to check for any underlying skin conditions, as suggested by 2
Systemic Diseases Associated with Itching
Itching with no rash can be a symptom of various systemic diseases, including:
- Disorders of iron metabolism, as mentioned by 4
- Chronic kidney disease, as noted by 4
- Chronic liver disease, especially cholestasis, as mentioned by 4
- Endocrine/metabolic diseases, as suggested by 4
- Hematological disorders, as noted by 4
- Malignant solid tumors, as mentioned by 4
Diagnostic Procedures
A comprehensive diagnostic workup is necessary to determine the underlying cause of itching with no rash. This may involve: