Flashcards in Endocrinology - ADH and Calcium Deck (69)
What is polyuria?
Increased urine production - 50 ml/kg/day
What is the normal urine production of a small animal?
What is polydipsia?
Increased thirst - 100 ml/kg/day
What is the normal water intake of a small animals?
True or false: The vast majority of animals are polydipsic first.
false - they are polyuric first
How does polyuria lead to polydipsia?
Polyuria leads to volume depletion which leads to polydipsia to prevent dehydration
True or False: Water restriction is not the answer to treat PU/PD.
What are the major differential diagnoses for PU/PD?
Osmotic diuresis, diabetes insipidus, renal medullary solute washout, drug-induced, and primary polydipsia
What is osmotic diuresis?
It is when there is an increase in urine solutes resulting in water pulled into the tubule and thus increased water loss through the urine
What are some disease processes that can cause osmotic diuresis?
Diabetes mellitus/DKA, Fanconi syndrome or primary renal glucosuria, CKD/AKI, and post-obstructive diuresis
What is diabetes insipidus?
A disorder characterized by the production of a large amount of dilute urine that occurs when water is not able to be reabsorbed from the renal tubule (action of ADH)
What are the two manifestations of diabetes insipidus?
central and nephrogenic
What is central diabetes insipidus also known as?
primary pituitary DI
What is central diabetes insipidus caused by?
A lack of ADH production - there is some issue with the pituitary gland
What is nephrogenic diabetes insipidus?
There is partial or complete lack of renal response to ADH
What are the two forms of nephrogenic diabetes insipidus?
Primary and secondary/acquired
What is primary nephrogenic diabetes insipidus?
Congenital lack of ADH receptors or lack of response to ADH- it has not been described in small animals
What can cause acquired NDI?
bacterual endotoxins, hypercalcemia, hyperadrenocorticism, hypokalemia, and others
What is renal medullary solute washout?
The loss of renal medullary solutes due to an impaired ability of the nephron to concentrate urine
What are the potential causes of renal medullary solute washout?
Hepatic disease, chronic diuretic use, and many other causes of PU/PD
What drugs are the 'common offenders' of causing PU/PD?
Anticonvulsants, glucocorticoids, and diuretics
What is primary polydipsia?
It is polydipsia that cannot be explained as a compensatory response to excessive whater loss
What is psychogenic polydipsia?
Behavioral compulsive water consumption - diagnosis of absolute exclusion
Why does polyuria develop in cases of psychogenic polydipsia?
to prevent overhydration
What is the clinical approach to PU/PD?
Get a history to verify, do a thorough PE, do a minimum database to rule out easy causes, use a UA to look for hyposthenuria or concentrated urine, and do additional diagnostics
What additional diagnostics can be done to diagnose the underlying cause of PU/PD?
UCCR, LDDST, T4, imaging, urine culture, leptospirosis testing, bile acids
What is a Desmopressin (DDAVP) trial?
It is a synthetic ADH analog that is used to tread CDI - if given and there is a positive response it is suggestive of CDI
What is a water deprivation test used for?
To determine if the patient has the ability to concentrate urine
What is the water deprivation test used to differentiate between?
Primary/psychogenic polydipsia and diabetes insipidus