The Thirst Axis

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27 Jun, 2017
Post author:Dr Tom Leach
Reading time:1 mins read
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Post category:Endocrinology

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ADH (/vasopressin) is synthesised in the hypothalamus.
From there it migrates in neurosecretory granules along axonal pathways to the posterior pituitary gland.
Secretion of ADH is principally in response to changes in plasma osmolality. It acts on the collecting duct of the kidney to cause water reabsorption via the translocation of aquaporin channels in the CD lumen, and is therefore stimulated when we need to conserve water volume. It is stimulated by large falls in blood pressure or volume.
At high concentrations, ADH also causes vasoconstriction.
ADH is suppressed at plasma osmolality <280mOsm/kg to permit maximal water diuresis.
ADH secretion reaches a maximum at an osmolality of >296mOsm/kg.

Dr Tom Leach

Dr Tom Leach MBChB DCH EMCert(ACEM) FRACGP currently works as a GP and an Emergency Department CMO in Australia. He is also a Clinical Associate Lecturer at the Australian National University, and is studying for a Masters of Sports Medicine at the University of Queensland. After graduating from his medical degree at the University of Manchester in 2011, Tom completed his Foundation Training at Bolton Royal Hospital, before moving to Australia in 2013. He started almostadoctor whilst a third year medical student in 2009. Read full bio