Diabetes insipidus Flashcards
What characterises Diabetes Insipidus (DI)?
The passage of large volumes of dilute urine (>3L/24hrs) with osmolality <300 mOsmol/Kg and excessive thirst.
What is the normal physiology of antidiuretic hormone (ADH)?
ADH, produced by the hypothalamus and stored in the posterior pituitary, binds to kidney receptors to reabsorb water, reducing urine volume and increasing osmolality.
What are the two main types of Diabetes Insipidus (DI)?
The two types are:
Central DI: Due to a deficiency of ADH.
Nephrogenic DI: Due to kidney resistance to ADH.
What can cause nephrogenic DI?
Nephrogenic DI can be caused by drugs such as lithium, orlistat, and demeclocycline, or due to genetic factors.
What is gestational DI?
Gestational DI is caused by the overproduction of vasopressinase by the placenta during pregnancy, leading to functional vasopressin deficiency.
What is the treatment for Central Diabetes Insipidus?
The treatment is desmopressin (oral, intranasal, or parenteral) to replace ADH deficiency, with regular monitoring of serum sodium and osmolality.
What is the treatment for Nephrogenic Diabetes Insipidus?
The treatment includes access to water, correcting metabolic abnormalities, stopping causative medications, and high-dose desmopressin for mild-to-moderate cases.
What is the role of desmopressin in the treatment of Diabetes Insipidus?
Desmopressin is a synthetic version of ADH, used to treat central DI and is also used in diagnosing DI by restoring urine concentration after water deprivation.
What are other uses of Desmopressin?
Desmopressin is used to boost factor VIII levels in hemophilia, to treat von Willebrand’s disease, and in the treatment of nocturnal enuresis (bedwetting).
What is the role of oxytocin?
Oxytocin is used in obstetrics to induce or strengthen labor and control post-delivery bleeding.
How is Demeclocycline hydrochloride used in DI?
Demeclocycline is used to treat hyponatremia caused by inappropriate ADH secretion when fluid restriction alone doesn’t help e.g. too much ADH so absorbing too much water therefore low sodium levels due to how dilute it is).
