Need help researching kidney disease diagnosis for granddaughter (4 yrs old)?

My 4 year old granddaughter was tested for diabetes insipidus due to excessive thirst and urination. Her blood pressure and cortisol levels were a little high, after testing. The doctor did an ultrasound of her kidneys and said they were enlarged and hard in appearance. Initial diagnosis is renal failure. She is scheduled for a kidney biopsy Feb.21st. There was no mention of possible cysts or tumors found (PKD)- her kidneys are filtering the toxins out of her blood - and she is otherwise healthy. All 3 of my daughters and I have a history of kidney infections and she has had several UTIs, as well. I don't know where to turn for information. She is in San Diego (navy brat) and I'm in Texas. ANY information would be greatly appreciated - I'm a wreck. There is talk of a kidney transplant from my daughter's (her mom) identical twin as her mother has hepatitis contracted during nursing school.

Diabetes Insipidus is a condition where the patient urinates excessive amounts of dilute urine. They have rapid water loss and run the risk of becoming dehydrated and hypernatremis (high sodium in the blood - a bad thing for a variety of reasons). The two common causes of DI are 1) Neurogenic - problems with the release of Antidiuretic hormone (which reduces the amount of water we pee out). and 2) Nephrogenic - problems in the kidney whereby the hormones are being produced but the kidney is unable to respond, so it cant reabsorb the water. From your description, it sounds like there may be a familial link to the disorder. However, be rest assured that the doctors will do their very best for her, because this isnt a new or unfamiliar condition, and lots of information and treatment options are available. Best of luck to your granddaughter, and hope everything works out!
PS: a good place to look would be Medline... the US government's website on health and related issues.