The Rudkin Family CDI Story

Our little boy Andrew is now just 5 years old and was diagnosed with central diabetes insipidus (CDI) in January 2000 when he was 3 and a half years old. Up until then he was a normal healthy little boy only ever having had treatment for a urinary tract infection due to kidney reflux as a baby, which he has since grown out of. [Editor's note: central DI is also referred to as pituitary or neurogenic DI.]

The onset of Andrew's symptoms were extremely sudden; there had been no history of brain trauma or surgery. It was Christmas 1999 and we were staying at my mother's in North Wales. Andrew wet the bed a few times that week which was very unusual for him, but we put it down to being away from home and the excitement of Christmas. However, I did think it strange that on one occasion he had wet the bed only two hours after going to sleep and then passed a large volume of urine straight after when we took him to the bathroom. We also noticed that he kept standing on a chair to drink water from the sink in the bathroom, and we assumed that this was the novelty of having a bathroom on the ground floor with a sink he could reach.

We left my mother's after the New Year and went on to spend a few days on holiday at Center Parcs in an apartment. Again, the bedwetting and drinking from the bathroom tap continued. We tried to distract Andrew from drinking so much in case it was becoming a habit, although we did not actually stop him from drinking (thank goodness). When we returned home, the other children went back to school on the 10th January 2000 and Andrew returned to his nursery. 

It was that week that I really noticed Andrew had a problem. I could not complete the morning or afternoon school run without Andrew needing to go to the toilet. I soon realized that Andrew was passing huge amounts of urine and that when he said he needed the toilet, he really did need it. The thirst continued and because Andrew couldn't reach the sink at home and had to ask for drinks each time, I knew that what he was drinking was excessive. At night, he was often up every couple of hours going to the toilet and standing on the edge of the bath to drink from the bathroom sink. He still wet the bed sometimes and obviously wasn't getting much sleep, as indeed we weren't. 

The first thing I did was to cut out all 'nice' drinks like squash and fruit juice and give Andrew only water to drink to see if he was less interested in drinking. This had no effect on his extreme thirst, and he began to go on about how much he liked water. As my husband is an insulin dependent diabetic we thought that Andrew's symptoms could only mean one thing - diabetes mellitus. We did blood glucose tests at home on Andrew. We pricked his finger at least two or three times because we were incredulous that each reading was normal.

I looked up 'diabetes mellitus' in my family medical encyclopedia just to check that the initial symptoms were what we thought they were. Under diabetes mellitus was a very small paragraph on DI stating that it was a very rare condition. I was starting to suspect that this might be Andrew's problem but doubted that he could have something so rare. I went to the G.P. with Andrew and even mentioned DI to her. She said, "I've got 300 patients with diabetes mellitus and about 2 with DI, it can't be DI." I asked her to do a blood test to check our home glucose machine was working correctly and the reading was normal. She advised me to bring him back the following week after having eaten a sugary donut. She was still thinking it must be diabetes mellitus and that the donut would be enough to raise his blood sugar levels if he had this condition. However, she did send off a blood sample for analysis to the local hospital.

After we left the doctor's, I took Andrew to the sweet shop as a reward for being good about his blood test. Whilst we were in the shop, Andrew was gazing at the drinks' fridge and asked me for one. I refused saying we'd be home soon and encouraged him to have a little packet of chocolate. As I turned round I saw Andrew drain the newsagent's cup of tea that had been left on the floor near some papers he was putting out. I was horrified and Andrew quickly put the cup back knowing that he shouldn't have done it. That moment will haunt me forever; he must have been so thirsty to be so desperate. We went on to the school to collect Andrew's siblings and whilst waiting in the playground I saw Andrew trying to drink from a drainpipe!

I phoned a friend who was a renal nurse for advice wondering if Andrew's kidney problem as a baby could be the reason for this. She suggested that I do a fluid input and output chart to see how much he really was drinking. I also took him to see a cranial osteopath who told me that she thought something was wrong with Andrew as his whole system was depressed, but she didn't know what. I trusted her instincts, as she had treated us successfully in the past for other ailments.

The following day I started our fluid input and output measurements. I had two measuring jugs on the go in the kitchen; one for what Andrew was drinking and one for measuring his urine. He thought it was great fun peeing into a jug and being allowed to drink as much water as he asked for. Whilst standing in the kitchen with Andrew doing one of our many measurements, I just caught a look in his eyes and I thought to myself, "there's something seriously wrong with you." I don't know if it was a mother's instinct, but I vowed at that point to get the doctors to listen to me no matter what. 

After seven hours he had taken in and excreted out about two litres of water. The input roughly balanced the output as he had been given free access to water. That evening I phoned NHS Direct (a medical advice line staffed by nurses) to see what were normal fluid inputs and outputs for a three year old. After investigating and following their series of questions they phoned me back at about 9pm and advised me to seek medical help within the hour either by going to the hospital or by calling a doctor out. Given our G.P.'s response last time I decided to take Andrew straight to the hospital. 

We arrived in casualty at about 10pm and Andrew was assessed by the nurse and eventually seen by a doctor. I showed them my fluid charts and blood and urine tests were taken and we were told to wait. A male doctor came back twice to me asking for another urine sample saying that the one we had given him was water and the machine could not read it. I explained that this was the urine that Andrew was passing and I could not help it if it was water. We waited for hours on a chair in the waiting room with Andrew dozing off on my lap waking every so often for a drink and the toilet.

At about 4 am I carried Andrew in my arms to the doctor's desk and asked if the blood results were back yet. The doctor looked at me and asked if I would rather be admitted whilst they investigated Andrew. I said yes that was why I had come. The female doctor said she thought that mothers always know when something is wrong. I will always be grateful to her for that and I found out later that she was a mother herself.

The following day, Friday 14th Jan, Andrew was subjected to a fluid deprivation test. My husband had come into the ward to be with us for the day whilst the other children were at school. This test was the worst thing ever. The doctors explained that if Andrew had DI he would be unable to concentrate his urine and that his weight would go down as he excreted fluid that he was unable to replace. We had to measure his urine output and he was weighed every hour. Initially when I saw that he was still peeing as much despite not drinking, I felt vindicated. As time went on however, I just felt so upset for Andrew. He was pleading for a drink and we kept trying to distract him by playing games with him. 

In the bathroom he was begging me for a drink from the tap, "just one tiny drink please and we won't tell the doctors." I felt absolutely terrible. The doctors warned us to watch Andrew like a hawk, as he would probably be desperate enough to steal another child's drink. A few hours into the test and they decided to weigh Andrew half hourly as his weight loss was becoming too much. Not long after, they abandoned the test as he had lost more than 5% of his body weight.

Andrew was given a nice cup of squash, which he downed immediately followed by five cups of water. He was then promptly sick in the sink from the sudden volume of fluid. After that Andrew was reasonably happy on the ward as he could drink what he liked and play with the toys. He was only upset about the cannula in his hand from which they took blood at regular intervals. We used to call it his "ribena tap." 

At this stage we knew Andrew had DI, but we didn't know whether it was central or nephrogenic DI. I couldn't decide what was worse, central DI which could be effectively treated with a drug but that in the absence of a head injury meant that it could be caused by a brain tumour, or nephrogenic that really had no perfect treatment and many dietary restrictions, but probably no sinister cause. I thought perhaps it was nephrogenic given that Andrew had a history of kidney problems and also I read that the symptoms of this type of DI can be delayed if the baby is breastfed. I had breastfed Andrew for 2.5 years, partly because he has a cows' milk allergy. 

Andrew was given a dose of dDAVP (artificial vasopressin) as a nasal spray. It was like a miracle, he didn't want to drink or go to the toilet, other than as a normal child. The doctor came and told us what we already knew, that Andrew had CDI. All I thought was "brain tumour," I couldn't understand how he could look so healthy. At 2am that morning the doctor came back to see me as I was so scared and upset. I remember standing in her office in my nightdress whilst she explained that he would have to undergo an MRI scan and that we would be sent to see a specialist at Great Ormond Street Hospital who would be able to answer all my questions. She also told me that most pituitary tumors were operable, non-malignant and that in the worst scenario if other hormones became affected they could all be replaced artificially. The doctor told me that this was the first case of DI she had seen. 

I quickly realized how rare DI was when we had numerous medical students coming in to see us and asking questions. A nurse who had worked on the children's ward for 20 years said that in all her years of doing fluid deprivation tests, she had never seen a positive one until now. The doctors couldn't answer most of our questions, which was quite frightening and they were getting information from the Internet for us. They rang Great Ormond Street Children's Hospital every day for advice regarding dosages of dDAVP. Also, our G.P. actually had the decency to phone the ward and apologise for not making the diagnosis, herself, which was nice.

Andrew's first dose of dDAVP spray lasted 30 hours and I was hoping that the diagnosis had all been a mistake and that Andrew had recovered. He seemed so normal running about on the ward where other children were sick. I asked the doctors if he was better, but they said no, and sure enough as the medication wore off he was back to square one again. I wished that he could have had diabetes mellitus instead because at least we would have known what we were dealing with. I heard other mothers concerned about their children who had come in for appendix operations etc. and I thought, 'but your child is going to get better, mine might have a brain tumour'. 

We tried to explain to Andrew why he was in hospital as best as you can to a 3 year old. His skin was very dry and the soles of his feet had cracked (from dehydration presumably), but he had always been prone to eczema anyway which was aggravated by cows' milk or stress. Whilst on the ward Andrew contracted a nasty stomach bug for a few days, which at least made him stop asking to go home because he actually felt unwell. The bug caused extra problems for the doctors who were trying to balance his new medication. They were trying him on dDAVP tablets, but had to go back to the nasal spray whilst he was sick.

I had been sharing Andrew's bed with him since we were admitted to the hospital as there were not enough camp beds for parents as the ward was full. I was feeling pretty dreadful as I was six weeks pregnant as well and spent many hours in the night crying down the phone to my mother and husband. My husband and I decided to spend a night each with Andrew whilst the other one went home to look after the other children. Andrew's bigger sister who is less than two years older than him and very close to him was absolutely distraught. She kept breaking down in tears at home and when she visited him in hospital each day she would rub cream into cracked feet and wince at his cannula bruises. Andrew's older brother was nine at the time and we explained what was going on to him in more detail.

Friends from the school helped where they could by providing meals and collecting the other children if we were both at the hospital. Many friends and family sent gifts and cards for Andrew. Things at home just ground to a halt and didn't seem important anymore. I had just started a career break from work, which was timed beautifully, and my husband was given the weeks off work whilst we were in hospital.

We were transferred to Great Ormond Street Hospital for the day only for further tests of Andrew's pituitary gland function. His body was put into a state of stress by inducing a hypoglycemic state to make the body produce hormones. Blood samples were taken every 20 minutes to measure the different hormones to see if any others were affected other than vasopressin. Andrew was obviously distressed by this test and I was in tears as I felt he had suffered enough. I realized that Great Ormond Street Hospital was a centre of excellence and even the nurses were familiar with DI. I pleaded and begged for Andrew to be transferred to this hospital for the rest of our stay. The consultant eventually agreed to this. 

Being on the ward at Great Ormond Street soon put our problems with Andrew into perspective, there were so many children with dreadful syndromes that we realized how lucky we were. I also met other parents of children with DI, where their DI was the least of their problems. I did find that their DI was probably only partial since the nurses were surprised at how extreme Andrew's thirst was when he needed more medication. I didn't meet anyone else with isolated DI, although my husband did manage to contact a mum in the UK via the Internet who had been through exactly the same as us with her son a year ago. She was a great source of comfort for us via emails whilst we felt so alone in hospital (and continues to be now) as her son was diagnosed at the same age as Andrew the preceding year. We also found the Dif website to be excellent for information.

The hormone test showed that Andrew's other hormones were functioning as normal. He had an M.R.I. scan under general anesthetic whilst we were at the hospital. We stayed for a few more days whilst the doctors juggled with his DDAVP dose trying to get it right. We worried about what to do when we got home, but the nurses explained about the medication and we were given a phone number to speak to an endocrine doctor for advice. We saw the Pediatric Endocrine Consultant who was the man for DI apparently. I went in with a list of 31 questions, determined not to leave until I'd put every one to him. I was quite shocked that he did not know the answers to many of my questions, as DI is so rare. However, he did tell us that Andrew probably had idiopathic DI and if you had to have a chronic condition, then this was probably quite a good one to have!

After we left hospital, we got on with life again getting used to Andrew's tablets and watching his urine output carefully. He still had to have bloods taken from time to time to check that the dDAVP dose was not too high. We discovered that Andrew becomes bad tempered when he needs his dDAVP, we're not sure if this is due to slight dehydration. He also suffers from more headaches than a child of his age would normally, particularly after just taking DDAVP or when he runs out of it. Andrew has had frequent increases in the dosage of dDAVP and is now on 3.5 tablets per day of 0.1mg dDAVP. He remains settled for a few months and then will start to run out long before each dose is due, his skin becomes very dry and itchy and his feet crack. When he has got to this stage for a while (just to be sure it is not just an odd day) we then contact his endocrine specialist who advises us what to increase the dose to. Andrew then has to have bloods taken to check that the new increase is not too much.

We have found that when Andrew is ill (for example when he had chicken pox), he needs far less dDAVP so we have to judge the dosage based on his urine color. Also when he goes to bed later, he runs out of dDAVP more quickly than he would if he were asleep. We never give extra dDAVP because of the risk of overdosing him, but we make sure he has ample fluids to compensate. Medication wise, we are lucky that he has tablets that he can chew rather than having to have injections as with diabetes mellitus, and we are also lucky in the UK that the drug is free. We are grateful that dDAVP exists, because our lives would be impossible without it.

Wherever we go, we carry bottles of water and we know where every public toilet is in our home town! Andrew wears a Medic Alert bracelet with details of his condition. He has since started full time school and manages very well so far. His teachers have all been informed and I have made a laminated sheet with information about Andrew's DI to hang in the staff room. Only once did the school have to ring me and that was to say that Andrew had drunk 3 bottles of water and kept going to the toilet. As the teacher spoke to me I realized that I had forgotten his morning dDAVP! I quickly popped along to the school to administer the tablet and Andrew was fine.

I still can't get over the suddenness of Andrew's DI, I keep looking back to see if there were any clues before that Christmas. The only thing I can find is that for the preceding six months or so Andrew had lost his appetite and was more tired than usual. He still had afternoon sleeps sometimes then, but I put it down to starting nursery. He didn't each much of his evening meals and I had cut out puddings in an effort to try and get him to eat more of his meals, but he wasn't bothered by this. I look at photographs of him before he was diagnosed trying to look for clues, to see if there was any hint of what was to come. We constantly ask ourselves 'why?'

I think I was lucky that Andrew was diagnosed so quickly, but a lot of it was to do with my pushiness! I have learnt from this to always trust my mothering instinct, and that doctors don't always know best. In a way I am grateful for DI, mostly because it has taught me to value the time with my children more. I have not returned to full time work since, and we have moved out of London to the country to a cheaper house so that we can afford for me to be at home. I will return to work in the future, but only part time and only when Andrew is a bit older.

All our children love living in the country, they are much healthier; they walk to school each day and ride their bikes. Andrew has put his weight back on and is getting quite muscular legs from all his tearing about on his little bike. He is a lively, energetic little boy who is always smiling and loves to make others laugh. He copes very well with his DI although he is not too keen on the annual hospital check ups. His MRI scans show no tumor so far (although the first one showed a thickening of the pituitary stalk which was not evident on the second one), but we live with the possibility that one day they might find something. We also know that there is the risk of further loss of other hormones from the pituitary gland especially if an, as yet, undetectable tumor is the cause.

We are hoping to have some genetic testing done to see if this could be a reason for Andrew's DI, particularly as his baby brother was born in September 2000 and may potentially be at risk of DI. But for now, we're just getting on with our lives and enjoying our children as much as we can.