Endocrine Abstracts

Arginine Vasopressin (AVP) deficiency belongs to the polyuria polydipsia syndrome, which is defined as polyuria of >40-50ml/kg BW per day and accompanying polydipsia. It is crucial to differentiate AVP deficiency from AVP resistance and primary polydipsia since treatment differs and a wrong treatment can have dangerous consequences. For decades, the “gold standard” for differential diagnosis has been the standard water deprivation test. However, this test has several limitations leading to an overall limited diagnostic accuracy. Direct measurement of Vasopressin upon osmotic stimulation was first shown to overcome these limitations, but failed to enter clinical practice mainly due to technical limitations of the AVP assay. New test methods based on stimulated measurement of copeptin, the surrogate marker of AVP, have shown promising results. The hypertonic saline stimulation test is currently the test with the highest diagnostic accuracy, but other test methods have either been tested (e.g. arginine) or are currently under investigation. This talk will show how AVP deficiency can be diagnosed or excluded at the baseline exam and will highlight different stimulation tests in those patients in which the diagnosis at baseline can not be made. Treatment of AVP deficiency is usually straight forward and consists of exogenous desmopressin orally or nasally, started at bedtime, and if symptoms persist during the day, a morning dose is added. The most common side effect is hyponatremia, and it is therefore important to inform patients about the risk of hyponatremia following desmopressin treatment and to instruct them about the Desmopressin escape method. Also, data will be shown highlighting psychological comorbidities in patients with AVP deficiency, and the possibility of an oxytocin deficiency underlying these psychological comorbidities will be discussed.