Pituitary: Diabetes Incipidus

Question 1

What is Cranial Diabetes Insipidus?

Answer 1

Lack of Anti-diuretic Hormone (ADH) production from the hypothalamus

Cranial DI is characterized by the hypothalamus not producing ADH.

Question 2

What is Nephrogenic Diabetes Insipidus?

Answer 2

Lack of RESPONSE to Anti-diuretic Hormone (ADH)

Nephrogenic DI occurs when the kidneys do not respond to ADH.

Question 3

What hormones are involved in Diabetes Insipidus?

Answer 3

Anti-diuretic hormones (ADH/Vasopressin)

ADH is produced by the hypothalamus and secreted by the posterior pituitary gland.

Question 4

What is the role of ADH?

Answer 4

Stimulates water reabsorption from the collecting ducts in the kidneys

A lack of ADH leads to an inability to reabsorb water and concentrate urine.

Question 5

List the main symptoms of Diabetes Insipidus.

Answer 5

• Polyuria
• Polydipsia
• Dehydration
• Postural hypotension

These symptoms result from the loss of water in the body.

Question 6

What is Primary polydipsia?

Answer 6

Normally functioning ADH system but the person drinks too much

It is a behavioral condition leading to excessive thirst and fluid intake.

Question 7

What can cause Cranial Diabetes Insipidus?

Answer 7

• Brain tumours
• Injury
• Surgery
• Infection (meningitis or encephalitis)
• Gene mutation (autosomal dominant)
• Wolfram syndrome

Wolfram syndrome also causes optic atrophy, deafness, and diabetes mellitus.

Question 8

What can cause Nephrogenic Diabetes Insipidus?

Answer 8

• Medications (Lithium)
• Genetic mutations in ADH receptor gene (X-linked)
• Hypercalcaemia
• Hypokalaemia
• Kidney disease (CKD)

Nephrogenic DI can be idiopathic or have identifiable causes.

Question 9

What are the expected results of urine osmolality in Diabetes Insipidus?

Answer 9

Urine osmolality is LOW in Diabetes Insipidus

This occurs due to the excessive dilution of urine from high amount of water in the urine

Question 10

What is the serum osmolality expected in Diabetes Insipidus?

Answer 10

HIGH

High serum osmolality occurs due to a lack of water to dilute proteins.

Question 11

What does a 24-hour urine collection show in Diabetes Insipidus?

Answer 11

Excessive urine production with more than 3L/hr

This indicates excessive urine production.

Question 12

What test is used to diagnose type of Diabetes Incipidus?

Answer 12

**Water deprivation test **- A test to assess the response of urine osmolality to desmopressin after fluid deprivation

It helps differentiate between types of Diabetes Insipidus.

Question 13

What happens in Cranial Diabetes Insipidus after desmopressin is given?

Answer 13

Urine osmolality becomes HIGH - kidney just react normally as they now have ADH

This indicates that kidneys respond to the synthetic ADH.

Question 14

What happens in Nephrogenic Diabetes Insipidus after desmopressin is given?

Answer 14

Urine osmolality remains LOW as they cannot react to the ADH!

This is due to the kidneys’ inability to respond to ADH.

Question 15

How is the underlying cause of Diabetes Insipidus managed?

Answer 15

By treating the underlying cause, e.g., stopping Lithium

Management may include various interventions depending on the type of DI.

Question 16

What is the treatment for Cranial Diabetes Insipidus?

Answer 16

Desmopressin (synthetic ADH)

remeber: monitor sodium levels due to risk of excess water loss and hyponatraemia!

Question 17

What are the management strategies for Nephrogenic Diabetes Insipidus?

Answer 17

• Ensuring access to plenty of water
• High-dose desmopressin
• Thiazide diuretics
• NSAIDs

These strategies help to manage symptoms and improve hydration.