Question:
Which of the following is considered a surrogate marker of vasopressin (ADH) in clinical practice?
Which of the following is considered a surrogate marker of vasopressin (ADH) in clinical practice?
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Copeptin is equimolarly co-secreted with AVP from pre-pro-vasopressin. Extremely high baseline copeptin ($>21.4\text{ pmol/L}$) indicates Nephrogenic DI, whereas low/unstimulated copeptin indicates Central DI.
Updated On: Sep 3, 2026
- Cortisol
- Aldosterone
- Copeptin
- Renin
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The Correct Option is C
Solution and Explanation
Concept:
Arginine vasopressin (AVP), also known as antidiuretic hormone (ADH), is a nonapeptide hormone synthesized in the magnocellular neurosecretory neurons of the hypothalamus (supraoptic and paraventricular nuclei) and stored in the posterior pituitary gland.
Direct measurement of mature circulating AVP in clinical practice is notoriously difficult and unreliable, necessitating a robust, stable surrogate biomarker.
Explanation:
• Direct laboratory assay of AVP is technically challenging because AVP is a small, unstable molecule with a very short plasma half-life ($10\text{--}20\text{ minutes}$), binds extensively to circulating platelets ($>90\%$), and rapidly degrades in vitro even at low temperatures.
• AVP is synthesized as part of a larger 164-amino-acid precursor pre-pro-vasopressin, which contains a signal peptide, mature AVP, neurophysin II, and a 39-amino-acid glycopeptide called Copeptin (C-terminal pro-AVP).
• During axonal transport and secretory vesicle processing, pre-pro-vasopressin is cleaved into equimolar amounts of AVP, neurophysin II, and copeptin.
• Copeptin is stoichiometrically co-secreted into the systemic circulation in a 1:1 ratio with AVP.
• Unlike AVP, copeptin is exceptionally stable in uncooled serum/plasma for days, does not bind platelets, and can be measured rapidly and precisely using automated sandwich immunoassay techniques.
• Plasma copeptin measurement (basal or following hypertonic saline arginine stimulation) has emerged as the modern gold-standard biomarker to differentiate Central Diabetes Insipidus from Nephrogenic Diabetes Insipidus and Primary Polydipsia.
Final Answer:
Copeptin is the established, stable surrogate biomarker for vasopressin (ADH) measurement in clinical practice.
Arginine vasopressin (AVP), also known as antidiuretic hormone (ADH), is a nonapeptide hormone synthesized in the magnocellular neurosecretory neurons of the hypothalamus (supraoptic and paraventricular nuclei) and stored in the posterior pituitary gland.
Direct measurement of mature circulating AVP in clinical practice is notoriously difficult and unreliable, necessitating a robust, stable surrogate biomarker.
Explanation:
• Direct laboratory assay of AVP is technically challenging because AVP is a small, unstable molecule with a very short plasma half-life ($10\text{--}20\text{ minutes}$), binds extensively to circulating platelets ($>90\%$), and rapidly degrades in vitro even at low temperatures.
• AVP is synthesized as part of a larger 164-amino-acid precursor pre-pro-vasopressin, which contains a signal peptide, mature AVP, neurophysin II, and a 39-amino-acid glycopeptide called Copeptin (C-terminal pro-AVP).
• During axonal transport and secretory vesicle processing, pre-pro-vasopressin is cleaved into equimolar amounts of AVP, neurophysin II, and copeptin.
• Copeptin is stoichiometrically co-secreted into the systemic circulation in a 1:1 ratio with AVP.
• Unlike AVP, copeptin is exceptionally stable in uncooled serum/plasma for days, does not bind platelets, and can be measured rapidly and precisely using automated sandwich immunoassay techniques.
• Plasma copeptin measurement (basal or following hypertonic saline arginine stimulation) has emerged as the modern gold-standard biomarker to differentiate Central Diabetes Insipidus from Nephrogenic Diabetes Insipidus and Primary Polydipsia.
Final Answer:
Copeptin is the established, stable surrogate biomarker for vasopressin (ADH) measurement in clinical practice.
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