Sorry for the delay in responding and thanks to Patricia and Dr. Silberstein for the replies.
On Friday Dad was still not producing urine from his left kidney and we called the doctor's office again. I also sent another (and stronger!)email to the doctor, and no sooner did I send it that he called me on the phone. Evidently, he had been giving a lecture in Chicago and had not received any messages from anyone.
He told me to get Dad to the ER for a CT scan to determine what was going on with the left kidney. While at the ER, the doctor's P.A. came to see Dad and ordered blood work. Dad's hemoglobin was at 8.0 and his sodium was critically low, as well. They found that the left stent had slipped slightly and they sent him back to the interventional radiologist to replace it. The P.A. also said that Dad needed to be admitted to the hospital (the one we had just left the day before!) to get his hemoglobin and sodium regulated.
A different interventional radiologist repositioned the left stent than the one who had put in the right stent and he told us the left stent had slipped and was blocked (we're not sure with what). This was the same stent that a different radiologist had told us was fine the day before. When this second radiologist found out that we were from a different city, he decided to save us a trip back to the hospital and remove the nephrostomy tube right then. That turned out to be a HUGE mistake. As he tried to remove the tube, evidently it was on or near an artery and Dad started spurting blood! They had a difficult time stopping the bleeding, but finally got it under control. He was admitted to the hospital and later that evening, Dad's hemoglobin had dropped to 6.3. He received two units of blood and they had him on a sodium drip.
His fluids were also restricted to 500cc per 24 hour period. It appears he was drinking so much water to flush his kidneys for the nephrostomy tube, he flushed all the good stuff out, too. It was a pretty scary situation.
It happened that Dad's urologist was on call over the weekend, so he came to see Dad in person at the hospital on Saturday. He said Dad was going to be fine and that his hemoglobin level will continue to increase. I'm not sure I believe that, but I have to trust that he knows what he's talking about. He let Dad go home after only one night in the hospital with hemo at 8+ and sodium at 128 (still lower than normal.)
Dad is monitoring his input and output now and not drinking so excessively as he was before. He is also drinking Gatorade and cranberry juice and not just water. He tires easily but does look better than before the trip to the ER and has been eating a tiny bit better. He has an appointment to see the doc on Tuesday and he plans to tell him that the stents that were put in are way too short. Guess he'll have to go back and have that adjusted. If it's not one thing, it's ten!
Interestingly enough, when the urologist came to see Dad on Saturday, he told me to not send him emails about emergency situations. I asked him what the heck I was supposed to do and he said call the Resident on call. Did that and also called his office several times. Nobody has ever called us back! When the doc called me on Friday, he said he had been on an airplane and had not received my emails until he got back to Dallas. That's when he picked up the phone to call me and tell me to get Dad to the ER. So, instead of a local ER, we drove to Dallas to go to the ER where Dad's doctor could direct the treatment. However, we didn't see him until the next day, but he did send his Physician Assistants to manage things at the hospital and a Resident to check on Dad Friday night. Such is life at a teaching hospital.
So, that's our latest saga. Thanks to those who replied with helpful suggestions.