What TEWL values indicate barrier impairment?

Normal TEWL (forearm): 3-10 g/m2/h. Mildly elevated: 10-20 g/m2/h. Significantly elevated: >20 g/m2/h. In severe AD, TEWL may exceed 30-50 g/m2/h in lesional skin. TEWL reduction correlates with AD treatment response.

How is TEWL measured clinically?

TEWL measured by Tewameter (open chamber) or VapoMeter (closed chamber). Standardized conditions: 20-22 C, 40-60% RH, no exercise 30 min prior. Measured at anatomically standardized sites (volar forearm, antecubital fossa in AD).

Does TEWL predict atopic dermatitis in neonates?

Yes. TEWL >=9.0 g/m2/h at 2 days in neonates predicts AD development by 2 years (sensitivity 71%, specificity 81%). FLG (filaggrin) mutation carriers have elevated TEWL before visible eczema appears.

Transepidermal Water Loss TEWL Threshold

Measure TEWL (transepidermal water loss, normal <10 g/m2/h on forearm) as a skin barrier function biomarker. Elevated TEWL (>20 g/m2/h) indicates impaired barrier in atopic dermatitis and ichthyosis.

⚕ Clinical Disclaimer: These calculators are for educational and reference purposes only. Always verify results with qualified clinical judgment and current clinical guidelines. Do not use as a sole basis for medical decisions.

How to Use

Enter the values for the scenario you are assessing. Measure TEWL (transepidermal water loss, normal <10 g/m2/h on forearm) as a skin barrier function biomarker. Elevated TEWL (>20 g/m2/h) indicates impaired barrier in atopic dermatitis and ichthyosis. Use the tewl threshold result to inform your calculation.

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