Antidiuretic hormone disorder

Question 1

What is diabetes insipidus?

Answer 1

• characterised by polyuria + polydipsia – body loses too much fluids by making large amounts of dilute urine, this can leave you feeling extremely thirsty
• not related to diabetes mellitus
• caused by problems w hormone vasopressin, also known as the antidiuretic hormone ADH

Question 2

What is the treatment for diabetes insipidus?

Answer 2

Cranial
- hypothalamus/pituitary don’t make enough ADH
- Treatment: desmopressin

Nephrogenic
- kidneys do not respond to ADH
- Treatment: thiazides

Question 3

What is the MOA of desmopressin?

Answer 3

• potent synthetic analogue of vasopressin (ADH) = conc urine
• longer duration of action + no vasoconstrictor effects

Question 4

What is the indication of desmopressin?

Answer 4

• Diabetes insipidus
• Nocturnal enuresis

Question 5

How do you administer desmopressin?

Answer 5

Nasal sprays, drops, sublingual tablets

Question 6

What are the side effects of desmopressin?

Answer 6

Hyponatraemia
- Headache, N+V, convulsions
- Caution: epilepsy, elderly
- CI: hyponatraemia

Oedema
- Caution: HF, HPT, migraine
- CI: conditions treated w diuretic

Question 7

What are the interactions of desmopressin?

Answer 7

• TCA: drugs that inc vasopressin secretion
• Diuretics, NSAIDs, SSRI -> hyponatremia

Question 8

What is syndrome of inappropriate diuretic hormone secretion (SIADH)?

Answer 8

• SIADH: hyponatraemia caused by inappropriate ADH secretion
• Condition where your body makes too much anti diuretic hormone vasopressin and too much water is conserved

Question 9

What is the treatment for SIADH?

Answer 9

Fluid restriction

Demeclocycline
- Blocks renal effects of ADH

Tolvaptan (V2 receptor antagonist)
- Avoid rapid correction: osmotic demyelination