Diabetes Insipidus Flashcards
What are the 5 steps seen in the stimulation of the secretion of ADH (vasopressin)?
- Volume contraction causes increased ECF osmolality.
- Increased ECF osmolality stimulates the osmoreceptors (in the hypothalamus).
- Stimulation of the osmoreceptors stimulates ADH secretion.
- Hypotension stimulates volume receptors.
- Stimulation of volume receptors stimulates ADH secretion.
What is ADH also known as?
Vasopressin
ADH stimulates reabsorption of water where in the kidneys?
What does this result in?
- Distal tubules and collecting ducts
- Increased water in ECF and decreased ECF osmolality
What does increased ECF osmolality stimulate?
The thirst center to increase water uptake.
How does increased water uptake affect the ECF?
Increases water in ECF and decreases ECF osmolality.
What is natural ADH (pitressin) used for?
How is it administered?
- Diagnosis of DI
- IM or IV over 1 hour in lactated Ringers or 5% dextrose
What are the 2 types of Diabetes Insipidus?
- Central diabetes insipidus (CDI)
- Nephrogenic diabetes insipidus (NDI)
What Is central diabetes insipidus caused by?
ADH deficiency
What is nephrogenic diabetes insipidus caused by?
Impaired responsiveness of the kidney to ADH.
What are 2 clinical signs associated with diabetes insipidus?
- Polyuria
- Polydipsia
What are 3 possible drug choices for the treatment of diabetes insipidus?
- Desmopressin (DDAVP)
- Thiazide diuretics (hydrochlorothiaizde, chlorothiazide)
- Chlorpropamide
Which drug is the best choice for treatment of central diabetes insipidus?
Desmopressin (DDAVP)
Which drug is a synthetic analog of ADH?
Desmopressin (DDAVP)
How does Desmopressin compare to natural ADH?
Desmopressin is more potent and has a longer half-life.
What is the half-life of Desmopressin?
10-27 hours
What is the half-life of natural ADH?
20 minutes
Does Desmopressin have vasoconstrictor action?
Minimal
Is Desmopressin more selective on V1 or V2?
V2
What are 4 routes of administration for Desmopressin?
- SC
- IM
- IV
- Nasal drops instilled into the conjunctival sac
What is the drug of choice for CDI in dogs and cats?
Desmopressin
Which drug is an oral hypoglycemic sulfonylurea drug?
Chlorpropamide
What does Chlorpropamide require in order to be able to act?
The presence of some endogenous ADH.
Which drug is not very effective for the treatment of CDI in dogs and cats?
Chlorpropamide
What can be useful in both CDI and NDI?
Restricted sodium chloride intake.
