Uremic Frost

Fig. 16.1

Differential Diagnosis

Uremic frost should be distinguished from other possible diagnosis such as psoriasis, eczema, retention keratosis, atopic dermatitis, and postinflammatory desquamation [2, 4].

Diagnosis

Uremic frost is most commonly a clinical diagnosis. In a patient with ESRD and laboratory findings consistent with severe azotemia (often with blood urea nitrogen levels greater than 200 mg/100 mL), the classical dermatological finding of a whitish crystalline coating, or “frost,” on the skin can be diagnostic [1, 4].

Laboratory analysis of the frost scrapings is also possible, but is typically not necessary. Verification that the crystals are composed of urea or nitrogenous waste can confirm the diagnosis [2, 4]. This is done by first taking scrapings of the “frost,” or crystals deposited on the skin, and diluting them in normal saline [2–5]. The solution is then tested for elevated urea nitrogen levels. If the urea nitrogen level in the solution is elevated and comparable to the blood urea nitrogen level, the test is positive and the diagnosis is supported and confirmed [2–4]. For example, in one case report in the New England Journal of Medicine (NEJM), the laboratory analysis of the white crystalline deposition on the skin of a patient with ESRD found that the urea nitrogen level of the “frost” scrapings diluted in normal saline was 113 mg/dL, while the corresponding serum blood urea nitrogen level was 120 mg/dL [5].

Treatment

The treatment of uremic frost is management of the underlying causative condition, the elevated levels of serum blood urea nitrogen levels [1, 2]. HD or other forms of renal replacement therapy are the mainstay of treatment for patients with uremic frost, as this dermatological condition indicates life-threatening kidney failure [2–4, 6]. Typically after the initiation of HD, or other renal replacement therapies, resolution of the crystalline deposition, or “frost,” on the skin is noted [2–4, 6]. However, the time to resolution of uremic frost after the initiation of dialysis is unclear, but some case reports recount that the dermatologic finding disappeared after about three to seven days of treatment [3, 4].