Arginine Vasopressin (AVP) Deficiency: Diagnosis and Treatment - An Update.

The hypothalamo-neurohypophysial axis comprises magnocellular neurons in the supraoptic and paraventricular nuclei that traffic arginine vasopressin (AVP) and oxytocin (OXT) to the posterior pituitary for systemic release. AVP is the key endocrine determinant of water balance whereas OXT orchestrates parturition and lactation and shapes socio-emotional processing. AVP-D results from hypothalamic-posterior pituitary injury and presents with hypotonic polyuria, polydipsia, and vulnerability to dehydration when access to water is limited. The diagnostic task is to separate AVP-D from AVP-R and primary polydipsia. Copeptin-based stimulation tests have transformed this work-up by providing accurate readouts of AVP secretion. Treatment relies on individualized desmopressin with patient education to prevent hypernatremia and desmopressin-associated hyponatremia. OXT deficiency is only now entering clinical focus. It likely accompanies AVP-D in lesions affecting the hypothalamus/posterior pituitary and may contribute to social dysfunction, anxiety, and reduced quality of life; however, validated diagnostic tools and definitive therapeutic data are still lacking.