Anti-Diuretic Hormone (ADH)

  • ADH is produced in the hypothalamus and released into the blood by the posterior pituitary.

  • It helps to control blood pressure by communicating with the kidneys and blood vessels around the body.

  • ADH controls the amount of water able to leave your body in urine by communicating with your kidneys.

Further reading at You & Your Hormones here.

ADH Excess

Too much ADH can cause a rare type of hyponatremia (low sodium) where too much water in the blood dilutes the level of sodium in the body.

ADH deficiency

Too little ADH causes Arginine Vasopressin Deficiency (AVPD) (formally known as Diabetes Insipidus), where a lot of pale urine is passed, causing the body to rapidly lose water. This causes constant feelings of thirst and rapid dehydration. You may need to go to the toilet very frequently and need to constantly drink.

Testing for ADH deficiency

  • Serum osmolality and urine osmolality test measures levels of fluid in the blood compared to fluid levels in the urine.

  • A water deprivation test may be carried out in hospital to confirm a diagnosis of AVPD. This starts in the early morning and continues through the day. You are not able to drink or have any fluids throughout the test. Blood and urine samples are taken each hour to compare their concentration / osmolality. Blood pressure, body weight and urine volume passed are also measured.

  • AVDP is confirmed if the blood osmolality increases beyond a certain level but the urine fails to concentrate. If the urine concentration defect then corrects with the addition of ADH (given by injection as part of the test) cranial AVDP is confirmed.

  • This test is difficult and generally only done by doctors, and in centres, with some experience of arranging and interpreting it.

Treatment for AVDP

  • Your endocrinologist will advise you on how to manage your AVDP once confirmed. A mild level of AVDP can often be managed by ensuring you drink enough to compensate for fluid lost in urine.

  • A medication called Desmopressin can help manage more severe diabetes insipidus and your endocrinologist will closely monitor this.

  • Desmopressin comes in tablet form or as a nasal spray.

  • Once you start taking this it shouldn’t be stopped, and it is important that you wear a medical alert or carry a card with you to communicate this in case of emergency or hospital admission.

    You can find support and more detailed information for living with AVDP through the Pituitary Foundation here.

    Further reading at You & Your Hormones here.