Diabetes insipidus

Question 1

Abnormal […] (cranial cause) or […] (nephrogenic) to […] hormone

Answer 1

Abnormal quantity (cranial cause) or response (neprhogenic) to antidiuretic hormone

Question 2

large volumes of […] urine (more than […] litres in 24 hours and a […] osmolality (less than […] mOsm/kg)).

In addition to the large volumes of urine, patients tend to suffer from […] and […] thirst.

In children, failure to […] and […] may also be noted.

Answer 2

large volumes of dilute urine (more than 3 litres in 24 hours and a low osmolality (less than 300 mOsm/kg)). In addition to the large volumes of urine, patients tend to suffer from nocturia and excessive thirst.

In children, failure to thrive and enuresis may also be noted.

Question 3

Causes of Cranial Diabetes Insipidus

Head […]
Inflammatory conditions e.g. […]
Cranial infections such as […]
Vascular conditions such as […][…][…]
Rare […] causes
[…] (HIGH TRANSFERRIN SATS)

Answer 3

Causes of Cranial Diabetes Insipidus

Head trauma
Inflammatory conditions e.g. sarcoidosis
Cranial infections such as meningitis
Vascular conditions such as sickle cell disease
Rare genetic causes
HAEMOCHROMATOSIS

Question 4

Causes of Nephrogenic Diabetes Insipidus

Drugs e.g. […]
Metabolic disturbances e.g. […], […], […]
Chronic […] disease
Rare genetic causes (e.g. […] syndrome).

Answer 4

Causes of Nephrogenic Diabetes Insipidus

Drugs e.g. lithium
Metabolic disturbances e.g. hypercalcaemia, hypokalaemia, hyperglycaemia
Chronic renal disease
Rare genetic causes (e.g. Wolfram’s syndrome).

Question 5

TLDR: in DI, […] plasma osmolality, […] urine osmolality

Baseline investigations should include
- urea and electrolytes
- blood glucose (to rule out diabetes mellitus)
- urine dip
- paired […] and […] osmolality.

Diabetes insipidus is present when the serum osmolality is […] (>295milliOsmol/kg) with inappropriately […] urine (urine osmolality < 700milliOsmol/kg)

Answer 5

TLDR: in DI, raised plasma osmolality, reduced urine osmolality

Baseline investigations should include
- urea and electrolytes
- blood glucose (to rule out diabetes mellitus)
- urine dip
- paired […] and […] osmolality.

Diabetes insipidus is present when the serum osmolality is […] (>295milliOsmol/kg) with inappropriately […] urine (urine osmolality < 700milliOsmol/kg)

Question 6

Does a urine osmolality of >700 mOsm/kg exclude diabetes insipidus?

Answer 6

Yes

Question 7

Other tests

Answer 7

water deprivation test

Question 8

Management

1. nephrogenic diabetes insipidus
   - […]
   - low […]/protein diet
2. central diabetes insipidus
   - […]

Answer 8

Management

1. nephrogenic diabetes insipidus
   thiazides
   low salt/protein diet
2. central diabetes insipidus can be treated with desmopressin