Diabetes insipidus

Diabetes insipidus

Diabetes insipidus (DI) is a condition characterised by a deficiency in the action of antidiuretic hormone (ADH), also known as arginine vasopressin (AVP). ADH is synthesised by the magnocellular neurons in the supraoptic and paraventricular nuclei of the hypothalamus and stored in the posterior pituitary.

A deficiency in ADH secretion is known as cranial (central) DI, often referred to as arginine vasopressin deficiency (AVP-D), whereas insensitivity of the kidney to ADH is known as nephrogenic DI (arginine vasopressin resistance, AVP-R).

Causes of cranial DI

• idiopathic
• post head injury
• pituitary surgery
• craniopharyngiomas
• infiltrative
  • histiocytosis X
  • sarcoidosis
• DIDMOAD is the association of cranial Diabetes Insipidus, Diabetes Mellitus, Optic Atrophy and Deafness (also known as Wolfram's syndrome)

Causes of nephrogenic DI

• genetic
  Nephrogenic diabetes insipidus may be caused genetic mutations: - the more common form affects the vasopression (ADH) receptor - the less common form results from a mutation in the gene that encodes the aquaporin 2 channel
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  Importance: 37
  :
  • more common form affects the vasopression (ADH) receptor
  • less common form results from a mutation in the gene that encodes the aquaporin 2 channel
• electrolytes
  • hypercalcaemia
  • hypokalaemia
• lithium
  lithium
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  • lithium desensitizes the kidney's ability to respond to ADH in the collecting ducts
    Diabetes insipidus in patients taking lithium mechanism: lithium desensitizes the kidney's ability to respond to ADH in the collecting ducts
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    Importance: 72
• demeclocycline
• tubulo-interstitial disease: obstruction, sickle-cell, pyelonephritis
• haemochromatosis
  haemochromatosis
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  (some cases may also present with cranial DI)

Features

Features

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• polyuria
• polydipsia

Investigation

• high plasma osmolality (often >295 mOsm/kg), low urine osmolality (often <300 mOsm/kg)
  high plasma osmolality (often >295 mOsm/kg), low urine osmolality (often <300 mOsm/kg)
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• a urine osmolality of >700 mOsm/kg generally excludes diabetes insipidus
• water deprivation test
  water deprivation test
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• a desmopressin test can help differentiate cranial from nephrogenic DI (an increase in urine osmolality suggests cranial DI)

Management

• nephrogenic diabetes insipidus
  Nephrogenic diabetes insipidus management: thiazides/low salt/protein diet
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  Importance: 64
  • thiazides
  • low salt/protein diet
• central diabetes insipidus can be treated with desmopressin
  central diabetes insipidus can be treated with desmopressin
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+PassMedicine Notes

Diabetes insipidus (DI) is a condition characterised by a deficiency in the action of antidiuretic hormone (ADH), also known as arginine vasopressin (AVP). ADH is synthesised by the magnocellular neurons in the supraoptic and paraventricular nuclei of the hypothalamus and stored in the posterior pituitary.

A deficiency in ADH secretion is known as cranial (central) DI, often referred to as arginine vasopressin deficiency (AVP-D), whereas insensitivity of the kidney to ADH is known as nephrogenic DI (arginine vasopressin resistance, AVP-R).

Causes of cranial DI

• idiopathic
• post head injury
• pituitary surgery
• craniopharyngiomas
• infiltrative
• histiocytosis X
• sarcoidosis
• DIDMOAD is the association of cranial Diabetes Insipidus, Diabetes Mellitus, Optic Atrophy and Deafness (also known as Wolfram's syndrome)

Causes of nephrogenic DI

• genetic:
• more common form affects the vasopression (ADH) receptor
• less common form results from a mutation in the gene that encodes the aquaporin 2 channel
• electrolytes
• hypercalcaemia
• hypokalaemia
• lithium
• lithium desensitizes the kidney's ability to respond to ADH in the collecting ducts
• demeclocycline
• tubulo-interstitial disease: obstruction, sickle-cell, pyelonephritis
• haemochromatosis (some cases may also present with cranial DI)

Features

• polyuria
• polydipsia

Investigation

• high plasma osmolality (often >295 mOsm/kg), low urine osmolality (often 700 mOsm/kg generally excludes diabetes insipidus
• water deprivation test
• a desmopressin test can help differentiate cranial from nephrogenic DI (an increase in urine osmolality suggests cranial DI)

Management

• nephrogenic diabetes insipidus
• thiazides
• low salt/protein diet
• central diabetes insipidus can be treated with desmopressin