Lactose intolerance in systemic nickel allergy syndrome.

Some patients affected by nickel-contact allergy present digestive symptoms in addition to systemic cutaneous manifestations, falling under the condition known as systemic nickel allergy syndrome (SNAS). A nickel-related pro-inflammatory status has been documented at intestinal mucosal level. The aim of the present study is to evaluate the prevalence of lactose intolerance in patients affected by SNAS compared to a healthy population. Consecutive patients affected by SNAS referring to our departments were enrolled. The control population consisted of healthy subjects without gastrointestinal symptoms. All subjects enrolled underwent lactose breath test under standard conditions. One hundred and seventy-eight SNAS patients and 60 healthy controls were enrolled. Positivity of lactose breath test occurred in 74.7% of the SNAS group compared to 6.6% of the control group. Lactose intolerance is highly prevalent in our series of patients affected by SNAS. Based on our preliminary results, we can hypothesize that in SNAS patients, the nickel-induced pro-inflammatory status could temporarily impair the brush border enzymatic functions, resulting in hypolactasia. Further trials evaluating the effect of a nickel-low diet regimen on lactase activity, histological features and immunological pattern are needed.