Diagnosis and treatment of hypernatremia Saif A. Muhsin, MBChB, David B. Mount, MD  Best Practice & Research Clinical Endocrinology & Metabolism  Volume 30, Issue 2, Pages 189-203 (March 2016) DOI: 10.1016/j.beem.2016.02.014 Copyright © 2016 Terms and Conditions

Fig. 1 Osmoregulatory circuits in the mammalian nervous system. Sagittal illustration of the rat brain, in which the relative positions of relevant structures and nuclei have been compressed into a single plane. Neurons and pathways are color-coded to distinguish osmosensory, integrative and effector areas. Vasopressin (AVP) is synthesized in magnocellular neurons within the supraoptic (SON) and paraventricular (PVN) nuclei of the hypothalamus; the distal axons of these neurons project to the posterior pituitary (PP) from which AVP is released into the circulation. ACC, anterior cingulate cortex; AP, area postrema; DRG, dorsal root ganglion; IML, intermediolateral nucleus; INS, insula; MnPO, median preoptic nucleus; NTS, nucleus tractus solitarius; OVLT, organum vasculosum laminae terminalis; PAG, periaqueductal grey; PBN, parabrachial nucleus; PP, posterior pituitary; PVN, paraventricular nucleus; SFO, subfornical organ; SN, sympathetic nerve; SON, supraoptic nucleus; SpN, splanchnic nerve; THAL, thalamus; VLM, ventrolateral medulla. (With permission from Bourque CW, “Central mechanisms of osmosensation and systemic osmoregulation”, Nat Rev Neurosci 2008; 9:519–31). Best Practice & Research Clinical Endocrinology & Metabolism 2016 30, 189-203DOI: (10.1016/j.beem.2016.02.014) Copyright © 2016 Terms and Conditions

Fig. 2 A) A comparison of the response of circulating vasopressin to hemodynamic and osmotic stimulation in healthy adults. The shaded area represents the reference range of plasma arginine vasopressin under normal conditions of hydration with plasma osmolality varying from 284 to 293 mosmol/kg. (From Baylis PH, “Osmoregulation and control of vasopressin secretion in healthy humans”, Am J Physiol 1987; 253:R671-8, with permission). B) The influence of hemodynamic status on osmotic stimulation of vasopressin release in healthy adults. The heavy oblique line in the center depicts the relationship of plasma vasopressin to osmolality in normovolemic, normotensive subjects. Lighter lines to the left or right depict the relationship when blood volume and/or pressure are acutely decreased or increased by the different percentages indicated in the center circles. (From Robertson GL et al., “The osmoregulation of vasopressin,” Kidney Int 1976; 10:25–37). Best Practice & Research Clinical Endocrinology & Metabolism 2016 30, 189-203DOI: (10.1016/j.beem.2016.02.014) Copyright © 2016 Terms and Conditions

Fig. 3 The renal concentrating mechanism. Water, salt, and solute transport by both proximal and distal nephron segments participates in the renal concentrating mechanism (see text for details). Diagram showing the location of the major transport proteins involved; a loop of Henle is depicted on the left, collecting duct on the right. UT, urea transporter; AQP, aquaporin; NKCC2, Na–K–2Cl cotransporter; ROMK, renal outer medullary K channel; CLC-K1, chloride channel. (With permission from Sands JM, “Molecular approaches to urea transporters,” J Am Soc Nephrol. 13(11):2795–806, 2002). Best Practice & Research Clinical Endocrinology & Metabolism 2016 30, 189-203DOI: (10.1016/j.beem.2016.02.014) Copyright © 2016 Terms and Conditions