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Diabetes Insipidus Your feelings about Infertility conditions series: › Diabetes insipidus The Pituitary Foundation Information Booklets Working to support pituitary patients, their carers & families The Pituitary Foundation is a charity working About this booklet in the United Kingdom and Republic of The aim of this booklet is to provide information Ireland supporting patients with pituitary about diabetes insipidus. conditions, their carers, family and friends. You may find that not all of the information Our aims are to offer support through the applies to you in particular, but we hope it helps pituitary journey, provide information to the you to understand your condition better and community, and act as the patient voice to raise offers you a basis for discussion with your GP awareness and improve services. and endocrinologist. What is diabetes insipidus and why do we get it? 3 The two forms of diabetes insipidus 5 How is DI diagnosed and treated? 7 How is DI diagnosed? 7 What tests are carried out and how will they feel? 7 How is DI treated? 7 Aftercare 9 How will diabetes insipidus affect my life? 10 Prescriptions 10 Driving 10 Employment problems 10 Insurance & pensions 10 Personal medical identification 11 Toilet facilities card 11 National key scheme 11 Common questions 12-13 What DI means to me - a patient's story 14 Membership & donation information 15 2 Diabetes insipidus What is diabetes insipidus (DI) and why do we get it? Diabetes insipidus (DI) is caused by a problem with either the production, or action, of the hormone vasopressin (AVP). If you have DI your kidneys are unable to retain water. This leads to the production of large volumes of urine and, in turn, greatly increased thirst. DI can occur at any age, but is mostly found in adults. It is a rare disorder, affecting only about 1 in 25,000 people. To understand DI we need to understand a little about how the body regulates water balance - the difference between how much water the body takes in and how much it passes out. Water balance is very important for the body. A large proportion of what we are is made up of water. In addition, the amount of water we have in our circulation is a large factor in determining the balance of salt in our bodies. As with any function that is important, the body AVP (sometimes called Anti-diuretic hormone has a sensitive mechanism for regulating water or ADH) is a hormone released from the rear balance. Like any good mechanism it is also most part of the pituitary gland (the posterior simple, involving two key components: pituitary). This gland is located at the base of the brain, and is about 3 to 5 centimetres behind the bridge of the nose. AVP circulates in the • Vasopressin (AVP or ADH - anti- bloodstream and acts on the kidneys to reduce diuretic hormone) - which regulates the the amount of water that is passed out in urine. amount of water passed out of the body How AVP and thirst work together is best in urine. described with the help of the bath tub analogy. • Thirst and drinking - which determines As with a bath tub, the body likes to keep the the amount of water the body takes in. level of water it contains at the right level for its purposes. There are only two ways the level of water can be altered: • Water can be let in to the bath through turning the taps on; just as thirst and drinking can allow more water into the body Diabetes insipidus 3 What is diabetes insipidus (DI) and why do we get it? • Water can be let out of the bath through taking urine (it puts the plug in). On the other hand, the plug out; just as the body can let more if the body senses the level of water is too much, water out by reducing the amount of AVP it turns the thirst off (turning taps off) and produced and so letting more water to be passed makes less AVP (taking the plug out of the plug out of the body as urine hole). The level of water is therefore maintained Unlike a bath tub, the body is very good at through a combined approach. sensing the level of water it has on board. If it Together, AVP and thirst maintain water does not have enough and is dehydrated, it balance very effectively in both situations where triggers us to drink more through activating the water is either easy to find, or is scarce. DI occurs thirst (turning on the taps). At the same time, when this mechanism regulating water balance it makes more AVP and so reduces water loss in breaks down. 4 Diabetes insipidus What is diabetes insipidus (DI) and why do we get it? The two forms of diabetes insipidus (DI) 1. Cranial diabetes insipidus (CDI) NDI are the result of mutations affecting the CDI is caused by the partial or absolute lack of AVP-receptor (V2R) that is needed for the AVP. The lack of AVP means that the kidneys kidney to respond to AVP and reabsorb water. cannot retain the amount of water that the body The remaining cases are the result of mutations needs them to, and produces a lot of dilute urine. in the pore in kidney cells through which water The body is therefore reliant on only one of its two is reabsorbed (AQP2). Though each type of mechanisms to keep the amount of water in the inherited NDI has a different genetic cause, the body at the correct level, thirst and drinking. People symptoms of each are the same. with CDI are thirsty all of the time; they pass large Males are the most likely to display symptoms amounts of urine frequently through the day and of X-linked NDI, whereas males and females often have to pass urine several times at night. are equally likely to display symptoms of Sometimes CDI occurs on its own and the autosomal recessive form of NDI. This however in many cases, it is accompanied by loss is because the V2R gene is carried on the of other hormones made by the pituitary. This X-chromosome and males have only one may be through a problem in the development X-chromosome. A problem with a gene on this of the pituitary gland; a tumour within or near single X-chromosome can’t be counter-balanced the gland; or the result of an accident, or surgery by another normal X-chromosome (the position to, or near to, the gland. in females). Autosomal recessive NDI is carried CDI following pituitary surgery may be on a non-sex chromosome, so males and females temporary, only lasting a week or two. In some are equally likely to inherit the problem. cases it may be permanent. Acquired NDI is the more common form of 2. Nephrogenic diabetes insipidus (NDI) NDI and can occur at any time of life. Most NDI is a condition in which the kidneys do not often, acquired NDI is a result of the use of respond to the normal signal (AVP) to reduce the drug lithium. Acquired NDI can also result water loss. Thus, the kidneys are not able to from the use of other drugs, such as colchicine, absorb the water that passes through them. methoxyflurane, amphotericin B, gentamicin, The primary symptoms of NDI are polyuria loop diuretics and demeclocycline. It can also (passage of large volumes of urine) and polydipsia occur as a result of certain diseases and physical (excessive thirst and drinking). conditions, which can result in either permanent or temporary NDI such as: Inherited NDI may show up in the first weeks • chronic kidney failure of life. Symptoms can include irritability, • other kidney diseases failure to thrive, lack of appetite and vomiting. • abnormally low levels of potassium Investigation can reveal high blood levels of • abnormally high levels of calcium sodium. Up to 90% of the cases of inherited • sickle cell disease Diabetes insipidus 5 The two forms of diabetes insipidus (DI) • And rarely, during pregnancy Treatment of NDI There is as yet no cure for inherited NDI. Currently, NDI is managed by: • ensuring ready access to water • following a low-sodium (and sometimes low- protein) diet, and • using thiazide diuretics, alone or in combination with a prostaglandin inhibitor or a potassium-sparing diuretic, to reduce the volume of urine output. Thiazide diuretics can reduce an NDI patient's polyuria, but they may also deplete the body's stores of potassium. This depletion can cause other symptoms and may be dangerous. When What does it feel like to have DI? taking thiazide diuretics, the patient's potassium The main symptoms that you will feel are levels must be monitored. To maintain sufficient thirst (no matter how much you drink) potassium in the body, the addition of potassium and the need to pass urine very frequently, supplements or amiloride (but not both) to the even during the night. You will pass large treatment regime may be required. volumes of urine; you may pass as much as 4 - 10 litres of urine a day. It is important that you do not try to prevent this by ignoring your DI is not related to diabetes mellitus thirst and drinking less, or you will disturb the It is very important to point out that DI is not balance of water in your body. related to the type of diabetes most people You may well have symptoms of dehydration, have heard of - DIABETES MELLITUS for example feeling shivery and nauseous with which is very common and can also cause headaches.
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