Post-transplant health care monitoring may always be necessary for patients who are allergic to histamine. Thats the takeaway from a recent study that suggests that treating with the antihistamine methotrexate may increase allergy to a drug used to treat asthma.

The study published Feb. 3 in the journal Rheumatology followed seven patients who received methotrexate treatment for moderate to severe asthma and were then followed three weeks later.

During that time average urine sample concentrations of the histamine a protein in the bloodstream that shows up on medical electronic systems averaged 0. 3 MmL. Researchers also found that one patient in the group reported an elevated level of ecchymyxin a protein that forms tiny dried blood vessels in the lungs when measured at six months. Additionally the treatment caused changes in these urine vessel size and inflammation in the spleen a part of the lung that is the first organ to be affected in the patients.

Our study suggests that while methotrexate may decrease symptoms patients should not be discouraged from using prednisone to treat asthma; rather patients should be encouraged for the use of drugs containing the antihistaminic ingredients that resulted in increased urine U2 concentrations at the end of treatment says senior author Ulrich Otto MD a professor of radiation oncology at the University of Cincinnati.

So-called acute myeloid leukemia (AML) can be treated with prednisone which is administered as a once-a-day injectable non-invasive drug. Now Otto and his colleagues are investigating whether expanding the use of advanced-stage AML results in lower urine concentrations of histamine and other markers of inflammation. A similar study recently published in Thorax noted changes in urinary levels of histamine levels with the use of prednisone in AML patients.

Ottos group now plans to analyze urine samples to determine if exposure to histamine or other markers of inflammation are influenced by engaging in a long-term steroid-containing systemic therapy regimen instead of prednisone. As an add-on they will perform a urine analysis to further ascertain urine histamine levels to determine whether taking prednisone or another steroid pose different risks versus those associated with prednisone.

These studies indicate that in AML patients treated with prednisone versus methotrexate it may be important to introduce steroids if possible to lower urinary levels of histamine as well as in addition to any treatment options Otto says.

These findings could influence AML cancer screening recommendations in the outpatient clinic.