Bill Turner, 35, never knew that drinking a popular beverage could send his recovery from a double-lung transplant on a mysterious roller coaster ride.
It took a team of medical sleuths at Vanderbilt University Medical Center to discover that the wild up-and-down swings in levels of the anti-rejection drug cyclosporine were fueled by the Sun Drop soft drink Turner drank to quench his caffeine cravings. Solving the case identified a new food-and-drug interaction that could be harmful for all transplant patients, and, possibly, people taking a class of anti-cholesterol drugs called statins.
During a clinic visit to Aaron Milstone, M.D., assistant professor of Medicine and medical director of Vanderbilt's Lung Transplant Program, Turner's blood was drawn to monitor, among other things, the serum levels of the drug cyclosporine, which kept his body from rejecting his new organs. The levels, previously normal, were more than double the suggested concentration, creating the potential for drug toxicity and serious side effects, such as kidney damage or central nervous system damage.
The question was, why.
Milstone and transplant coordinator Haley Hoy questioned Turner extensively about the possibility of altered cyclosporine doses or any other changes in his new medical routine. Turner said he felt fatigued and was experiencing nervous tremors, but had done nothing different.
Turner was tested again two days later and his cyclosporine serum levels were well within therapeutic limits. This pattern repeated itself again at the next month's clinic visit: the cyclosporine levels were more than twice the accepted level on the day of the clinic visit, but then normal again upon retesting two days later.
"After this process of high and normal levels repeated itself, we began a dietary inquiry," Milstone said. "Is there something in Bill's diet that was doing this?"