Water Deprivation Test

If you have read the past few posts you then know I have had a few difficult years. In earlier posts I have shared my unexpected move, broken foot, and computer problems. What I have not shared is the health mystery I have been struggling with for years. I have gone to many doctors and done lots of praying, but as of this writing I am still living with a mystery, which is getting worse. I had seen an endocrinologist in 2006 who said I did not have an endocrine problem, but decided it was time for a second opinion earlier this year. Hopefully this doctor will have some answers for me soon.

Since my first visit to my current endocrinologist in March, I have had three 24 hour urine tests, lots of peeing in cups, to many to count blood draw’s (think I have given a gallon or kg of blood to that lab) and a trip to the hospital.

I was admitted to Christus Santa Rosa Hospital on April 20 for a Water Deprivation Test, which is used to determine if the patient has Diabetes Insipidus, also called Water Diabetes. It has nothing to do with the more common sugar diabetes (Diabetes Mellitus). Diabetes Insipidus is usually caused by a problem with the pituitary gland (injury or tumor), resulting in a lack of antidiuretic hormone being secreted. This hormone tells the kidneys to conserve water by concentrating the urine. A person with Diabetes Insipidus will continue to urinate no matter how dehydrated they may become. I have a lot of symptoms, but one of my most serious symptoms is chronic thirst. I am drinking two to three gallons of water daily (1 US gallon is equal to 3.79 liters).

The first thing I learned is just how rare this test is. When I told the nurse why I was in the hospital, her response was “what’s that”. After reading the doctor’s orders, she returned to say I was right but she had never heard of the test and was going to have to call my doctor to get more detailed instructions. During my 48 hour stay, every shift of nurses, lab techs, etc. said the same thing to me. They had never heard of this test before, let alone had to do the test on a patient. As I waited for my friend to pick me up when I was released, it became obvious to me I had been the talk of the floor because of my unique test.

So, what happens during a Water Deprivation Test? Basically, nothing by mouth for at least 24 hours and round the clock urine tests, blood tests, and weight measurements. I had my last drink of water around 1:30pm on Monday afternoon. I was not allowed to drink or eat anything until about 7pm Tuesday night. During that time they took a urine sample and weighed me every hour around the clock. Every two hours several vials of blood was taken. Having to get out of bed every hour for over 24 hours also meant I got very little sleep. Around noon on Tuesday my doctor visited me and decided my labs said it was time for a shot of antidiuretic hormone, formally referred to as vasopressin. After the shot I had 4 more hours of urine samples, getting out of bed to stand on the scale, and blood draws. Once I was given food and water, I no longer got weighed but the lab tests continued. I think I was told three times this was the last blood test, before they finally stopped poking me. My last blood test was around 3:30am on Wednesday. I would be released around 1 pm that afternoon. My friend got me back home around 2pm.

I still do not know the results from the Water Deprivation Test or the MRI of my pituitary gland I had a week later. I see my doctor next Tuesday and hopefully I will have some answers then.

I share this for one simple reason. Before going into the hospital I was unable to find any web site that told me what to expect from the test. The Diabetes Insipidus Foundation web site does have information for doctors but I found nothing for the lay person. If you are a patient reading this post, I would love for you to share your experience. It may help someone else facing this same test.