Polyuria and Polydipsia
What are 3 signs you should NOT perform a water deprivation test?
1. Azotemia 2. Dehydration 3. Hypercalcemia
REMINDER: What are your liver function parameters on a chem?
1. BUN 2. Albumin 3. Bilirubin 4. Glucose 5. Cholesterol
What are 2 ways to assess for central diabetes insipidus?
1. DDAVP (vasopressin) trial 2. Advanced imaging of brain/pituitary
If you're done a CBC/chem, UA, USG, rads/AUS, T4 and have ruled out everything you could possibly rule out with those tests, what are 4 things you need to work up?
1. Diabetes insipidus 2. Cushing's disease vs. Addison's disease 3. Neoplasia 4. Psychogenic polydipsia
Try your best :) Think of 12 common ddx for PU/PD
1. Diabetes mellitus 2. Diabetes insipidus (central or nephrogenic) 3. Hyperadrenocorticism (Cushing's disease) 4. Hypoadrenocorticism (Addison's disease) 5. Chronic renal insufficiency 6. Pyelonephritis 7. Hypercalcemia 8. Neoplasia 9. Liver failure 10. Hyperthyroidism 11. Endotoxemia 12. Iatrogenic
What are 4 neoplastic diseases that can lead to PU/PD?
1. Lymphoma 2. AGASACA 3. Multiple myeloma 4. Pheochromocytoma
What 2 causes of endotoxemia most commonly cause PU/PD?
1. Pyometra 2. Prostatic abscesses
What are 4 iatrogenic causes of PU/PD?
1. Steroids 2. Diuretics 3. Levothyroxine 4. High salt diet
For reference (less common causes of PU/PD): 1. Psychogenic polydipsia 2. Hyperthermia / stress / exercise / heat 3. Fanconi's syndrome 4. Acromegaly 5. Primary renal glucosuria 6. Hypokalmeia 7. Post-obstruction diuresis after urethral blockage
:)
A urine specific gravity of what makes renal insufficiency less likely?
< 1.008
What is polydipsia defined as in terms of ml/kg/day?
>100 ml/kg/day
A urine specific gravity of >1.035 should only be seen in PU/PD animals with what?
Marked glucosuria
What is important to remember when performing a DDAVP (vasopressin/ADH) trial in a patient that may have central diabetes insipidus but has had long-standing PU/PD?
May take several days to a week to overcome medullary washout of kidneys before an effect is seen
What test can be performed to rule in psychogenic polydipsia?
Water deprivation test