For the past year, a woman aged 64 years has had chronic pruritus without dermatitis. She has smoked two to three packs of cigarettes a day for the past 40 years. The pruritus began two months after the patient was diagnosed with adult-onset diabetes mellitus. Medications include rosiglitazone (Avandia), metformin, lovastatin, captopril, and atenolol. Other treatment includes prednisone (oral, topical, and intramuscular), cetirizine (Zyrtec), hydroxine (Atarax), montelukast (Singulair), and crotamiton (Eurax). A dermatology referral advised that she be treated for anxiety and prescribed expensive topicals. There has been no resolution. What do you suggest?—CAROLYN A. BAUTISTA, FNP, Homossa, Fla.
Pruritus without dermatitis may be a symptom of an occult disease. When initial symptomatic treatments are unsuccessful, it may be appropriate to look for an associated etiology for patients who have an itch without a rash (Aust Fam Physician. 2004;33:495-499). In this patient, the pruritus may be secondary to one of her medications or her diabetes mellitus. Evaluation for a systemic etiology could initially include a complete blood cell count (with iron, total iron binding capacity [transferrin], and ferritin concentration if anemic); erythrocyte sedimentation rate; complete metabolic panel (including fasting blood sugar, renal function, and liver function studies); thyroid function studies (including thyroid stimulating hormone); stool for occult blood, ova, and parasites; and urinalysis. Additional studies could include HIV testing, age-appropriate cancer screening (e.g., chest roentgenogram, abdominal ultrasound, and/or CT scan), immunoglobulins, serum protein electrophoresis and serum immunoelectrophoresis, antinuclear nuclear antibody, urine for 5-hydroxyindoleacetic acid (to rule out carcinoid), N-methylhistamine (to rule out mastocytosis), serum tryptase (to rule out mastocytosis), and skin biopsy (Ann Acad Med Singapore. 2007;36:788-792 and QJM. 2003;96:7-26). The management and treatment of pruritus, including novel agents for intractable itch, have recently been reviewed (Skin Therapy Lett. 2008;13:6-9; and Skin Therapy Lett. 2007;12:1-6).—Philip R. Cohen, MD (142-5)