Diabetes Insipidus Flashcards
How much decrease in AVP in DI?
≥ 75% in the secretion or action of AVP
Urine volume and Urine Osmolality in DI
24h urine volume >40 mL/kg BW
Uosm < 300mosmol/kg
Polyuria leads to what symptoms in DI
Urine frequency
Enuresis
Nocturia - may disturb sleep, cause mild daytime fatigue or somnolence
Slight rise in Posm stimulates THIRST and POLYDIPSIA
Clinical signs of dehydration uncommon unless fluid intake is impaired
Primary secretory deficiency in AVP results from what?
Results from a genesis or irreversible destruction of the neurohypophysis
Aka neurohypophyseal DI, neurogenic DI, pituitary DI, cranial DI or central DI
Post-surgical Pituitary DI
Results from surgery in or around the neurohypophysis
Generally appears within 24h which transitions i a few days to 2-3 week period of inappopriate anti diuretics, after which DI may or may not recur permanently
Gestational DI
Results from increased metabolism by an N-terminal aminopeptidase produced by the placenta;
S/sx manifest during pregnancy and usually remit several weeks after delivery
Most common primary secretory AVP deficiency genetic form
Autosomal dominant mutations in the coding region of on e allele of the AVP-neurophysin II (AVP-NPII) gene with DI developing over several months to years that may occasionally remit spontaneously in late middle age
What kind of secretory deficiency of AVP results form inhibition of secretion by excessive intake of fluids?
Secondary secretory deficiency
** Primary Polydipsia
3 categories of Primary Polydipsia
- Dipsogenic DI - inappropriate increase in thirst caused by altered set point in osmoredulation
- Psychogenic Polydipsia - feature of psychosis or OCD
- Iatrogenic Polydipsia
Primary deficiencies in the antidiuretic action of AVP result in what?
NEPHROGENIC DI
3 causes of NEPHROGENIC DI
- Genetic:
A. x-linked: mutations in the coding region of the V2 receptor gene
B. AR: mutations in the gene encoding the aquaporin protein - Acquired
- Exposure to drugs
Secondary Deficiencies in the antidiuretic response o AVP results in what
Polyuria - causes a washout in the medullary concentration gradient, resolves in 24-48h after correction of Polyuria
In a patient with Polyuria but 24 hour urine osmolality is > 300 mosm.kg, what should we evaluate for?
Uncontrolled DM
If plasma AVP is >1pg/ml:______
If <1 pg/ml:______
> 1pg/mlL NEPHROGENIC DI
<1 pg/mlL do BRAIN MRI
IF with pituitary bright spot: PRIMARY POLYDIPSIA
IF no pituitary bright spot: PITUITARY DI
What to do if with <40ml/kg and Uosm of >300mosm/L/
Do GU EVALUATION
