Running Long Distances with One Kidney...Is it OK?

  At 8 weeks of age, I was taken to the hospital.  According to my mother, I was very weak and colicky.  The problem was that I was in Africa and the health care was not that great in the area that we lived.  I was scene by the British Consulate doctor and was medevaced to the Capital.  At the city hospital, the doctor diagnosed my problem as a tumor on my right side.  After further tests, it was determined that I needed to be medevaced to Germany.  Once under more advanced medical care and testing, it was determined that it was not a tumor at all.  It was found that my kidney wasn't working and it had to be removed.  It never really fully developed and was taken over by cysts.  After surgery and recovery I was flown back to Africa.  Before leaving Germany, the doctor asked my father to promise him one thing--never let him play contact sports.  Needless to say, I broke that rule playing soccer most of my life, and dabbled in wrestling in high school and rugby in college.  Now, lets hit the fast forward button and here we are twenty years later.
  At 42, I started gaining weight and decided to take on running as a hobby to control my weight.  I started off small and over 3,000 miles later I've decided to take on my first marathon.  In October, I will run the MCM.   I've just started training, but have always heard that running such distances can put a strain on my remaining kidney.   Between dehydration concerns and just the stress that you put on yourself at that mileage, I'm just a little worried.  I finished a 20 miler late last year and felt OK, but cramped pretty bad in my chins and calves, but not in the kidney area.  I kept myself hydrated both before and after that race and still cramped.  This was probably because I didn't have any electrolytes in my system--at least I hope so.  After researching the topic, I've found that many runners have one kidney and have run multiple marathons.  I even reached out to the Runners World Sports Doctor and he said that as long as I keep hydrated and have no preconditions, I should be fine.  Here is a link to his article if your interested in more detail  http://sportsdoc.runnersworld.com/2011/04/can-i-run-a-marathon-with-one-kidney.html?cm_mmc=nutrition-_-05052011-_-nutrition-_-BLOG%3a%20Ask%20the%20Sports%20Doc.  So I'm going to go for it and try a little different strategy with fueling and hydration this time.  MCM or bust baby!  If you have any information to share on the topic, PLEEEAAAASSEEE Do So!