What investigations should be performed for xerosis?

Investigations for Xerosis

For isolated xerosis cutis (dry skin) without systemic symptoms, no specific laboratory investigations are routinely required—the diagnosis is made clinically based on visual inspection and patient history. 1, 2

Clinical Diagnosis

Xerosis is diagnosed on clinical grounds by identifying:

• Dry, rough, scaly skin with possible fissuring or cracking 2
• Distribution patterns: commonly affects lower legs, arms, and hands in elderly patients 3
• Associated symptoms: pruritus (itching) is frequently present but not universal 3
• Erythema: may be present, particularly when inflammatory changes develop 1

When to Investigate for Underlying Causes

Investigations should be performed when xerosis is severe, refractory to basic treatment, or accompanied by systemic symptoms suggesting an underlying condition. 3

Specific Investigation Scenarios:

For Generalized Pruritus with Xerosis:

If pruritus is prominent and generalized, consider screening for secondary causes 3:

• Renal function: Urea and electrolytes to exclude chronic kidney disease/end-stage renal disease, as xerosis is the most common cutaneous sign in dialysis patients 3
• Liver function tests: To exclude cholestatic liver disease 3
• Thyroid function: To screen for thyroid disorders 4
• Complete blood count: To identify anemia, eosinophilia (HIV-associated), or hematologic malignancy 3
• Fasting glucose or HbA1c: To exclude diabetes mellitus 3

For Elderly Patients (>65 years):

• Clinical assessment for asteatotic eczema is the primary approach 3
• Consider skin biopsy and indirect immunofluorescence if bullous pemphigoid is suspected, as pruritus with xerosis can rarely be the presenting feature 3
• Reassessment after 2 weeks of emollient and topical steroid treatment if symptoms persist 3

For Atypical Presentations:

• Dermatology referral for diagnostic uncertainty, concern for malignancy, or atypical features 4
• Wood's lamp examination and dermoscopy may help characterize unusual pigmentation or lesions 4
• Skin biopsy if there is concern for underlying dermatosis mimicking xerosis 3

Differential Diagnosis Requiring Investigation:

Consider and investigate for:

• Atopic dermatitis: More pronounced inflammation, lichenification, typical distribution; diagnosis is clinical but may require specialist assessment 3, 1
• Contact dermatitis: History of allergen/irritant exposure; patch testing may be indicated 1
• Eczema craquelé/asteatotic eczema: Clinical diagnosis but may require biopsy if uncertain 5
• HIV infection: Consider testing if risk factors present, as xerosis occurs in late-stage disease and correlates with viral load 3, 6
• Ichthyosis or genetic disorders: Family history and clinical features guide genetic testing 4

Molecular/Research Markers (Not Routine Clinical Practice):

While research has identified numerous molecular markers (ceramides, natural moisturizing factors, free fatty acids, triglycerides), these are not used in routine clinical diagnosis and remain investigational 7, 6. Standard clinical assessment remains the gold standard.

Key Clinical Pitfalls:

• Do not over-investigate isolated xerosis: Most cases are benign and respond to emollients without need for laboratory work 1, 2
• Do not miss systemic disease: If xerosis is severe, generalized, or associated with pruritus unresponsive to basic treatment after 2 weeks, investigate for underlying causes 3
• Elderly patients require vigilance: Follow up regularly as systemic causes may not be evident initially 3
• Drug-induced xerosis: Always obtain complete medication history including over-the-counter and herbal remedies 3