Diabetes insipidus

Question 1

what is diabetes insipidus

Answer 1

a condition where there is a lack of vasopressin or response to the pituitary hormone vasopressin is impaired. This causes the body to produce very large quantities of dilute urine, often with dehydration and thirst

note: vasopressin= antidiuretic hormone (ADH)

Question 2

which drugs are used for the treatment of diabetes insipidus

Answer 2

• vasopressin
• desmopressin (more potent and has a longer duration of action than vasopressin)
• carbamazepine (unlicensed but can sometimes be useful)

Question 3

how is the dosage tailored for diabetes insipidus

Answer 3

Dosage is tailored to produce a slight diuresis (urination) every 24 hours to avoid water intoxication

Question 4

what is the difference between cranial diabetes insipidus and nephrogenic diabetes insipidus

Answer 4

cranial diabetes insipidus- where the body does not produce enough vasopressin, so excessive amounts of water are lost in large amounts of urine

nephrogenic diabetes insipidus- where vasopressin is produced at the right levels, but, for a variety of reasons, the kidneys do not respond to it in the normal way

Question 5

how is desmopressin used in the differential diagnosis of diabetes insipidus

Answer 5

the patient is given a dose of desmopressin intramuscularly or intranasally, if the body responds to this and stops urination then it is likely the person has cranial diabetes insipidus.

• if the person does not respond to the dose of desmopressin (continues to urinate frequently), then it is likely the person has nephrogenic diabetes insipidus

Question 6

what can be used to treat hyponatremia in diabetes insipidus if fluid restriction alone doesn’t restore sodium concentration or fluid restriction inappropriate

Answer 6

Demeclocycline