I found it at my local library. Heavy cream is lower in lactose than light cream, which in turn is lower than whole milk. Butter is higher in fat than any of these, and in turn is the lowest in lactose. It was mentioned that aged cheeses are lower in lactose than non-aged cheeses because the lactose had been broken down during the aging process. So, even though lactase deficiency and gluten intolerance can give the same symptoms, they are not caused by the same processes.
Lactase is composed of two sugars.
The problems arise when you are unable to break it into its two parts and absorb them. Gluten is a protein. It seems to cause a problem due to an immunological response, and as far as I know, symptoms are the only similarities between the two. Quantitative estimation of the infiltration by intraepithelial lymphocytes and eosinophils of the mucosa was carried out in 21 children with cow's milk and 35 children with gluten intolerance. The role of genetic factors in the development of cow's milk and gluten intolerance among hospitalized children was the subject of analysis made by the authors.