what is polyuria?
Polyuria refers to a urine output >3L/day recognised from reviewing the fluid balance chart. It is different to frequency. Frequency refers to the frequent passage of urine, whether large or small volume.
Questions to ask over the phone before seeing this pt?
- what problem is present? (frequency, polyuria associated with dysuria or incontinence)
- vital signs
- is the pt catheterised?
- reason for admission?
- mental state of pt
- ask to check BGL
- request IDC if not already in
- urine sample with bedside urinalysis and prep sample to send for MCS
- ask if pt has IV access
Patient doenst have to be seen urgently unless pt is unstable, change in vital signs, mental status change, severe dehydration.
What are the potential causes of polyuria?
- DM- kidneys ability to reabsorb sugar is overwhelmed and glucose is passed in the urine, causing and osmotic diuresis
- Diabetes insipidus (DI): caused by either reduced ADH secretion (central DI) or failure of kidneys to respond to ADH (nephrogenic DI). Both result in kidneys being unable to reabsorb water in the distal tubule, associated with 5-10L urine output a day.
- Drugs- diuretics, mannitol, lithium toxicity, amphotericin B (nephrogenic Diabetes Insipidus)
- Renal disease: diuretic phase of ATN, post-obstructive diuresis, salt-losing nephritis, polycystic kidney disease (causes nephrogenic DI)
- hypercalcemia
- hypokalemia
which are both important reversible causes of nephogenic DI) - physiological diuresis- following large volume of PO or IV fluids
- psychogenic polydipsia (once everything else ruled out)
What is Diabetes Insipidus most commonly associated with?
- head trauma
- cerebral edema
- pituitary tumors
- medications
- post neurosurgical procedures
- 25% idiopathic
What are the potential causes of frequency?
- UTI
- partial bladder outlet obstruction (e.g. prostatism)
- bladder irritation (tumor, stone, infx)
- large fluid intake
- psyhcological
what is overflow incontinence and some causes?
Overflow incontinence is the involuntary release of urine—due to a weak bladder muscle or to blockage—when the bladder becomes overly full, even though the person feels no urge to urinate.
Caused by bladder outlet obstruction such as:
- BPH
- urethral stricture
- faecal impaction
What is stress incontinence and some causes?
Stress incontinence happens when physical movement or activity — such as coughing, laughing, sneezing, running or heavy lifting — increases abdominal pressure and puts pressure (stress) on your bladder, causing you to leak urine.
It is usually in multiparous women, caused by lax pelvic bladder support. In men it occurs after prostate surgery.
What is urge incontinence and some causes?
Is incontinence due to involuntary contraction of bladder muscles. It can be caused by:
- UTI
- diabetes
- urolithiasis
- dementia, stroke
- pelvic tumour
What is neurogenic incontinence?
incontinence due to impaired functioning of the nervous system
What are some other causes of incontinece?
- iatrogenic factors- diuretics, sedatives, Ach drugs, alpha blockers, Ca2+ channel blockers, ACEi
- environmental factors- inaccessible call bell, poor mobility, obstacles to bathroom
What are some major threats to life from polyuria?
- cerebral edema associated with DI
- Intravascular volume depletion
- DKA
- high output renal failure
What to look for at the bedside of this pt?
- Does the pt look well?
- vitals and other signs of dehydration
- does the pt have a fever- infx
What is the immediate management in cases of significant polyuria, intravascular depletion or systemic sepsis?
- attach continuous non nvasive ECG, BP and pulse ox monitoring to the pt
- maintain O2>94%.
- Insert a large bore 14-16G peripheral cannula; send blood samples for FBC, UEC, calcium. Add blood cultures if suspicious of infx
- commence fluid resuscitation
- Give a 20mL/kg normal saline bolus
- observe the effect of this fluid challenge on the BP
- Replace potassium and other electrolytes according to UEC
- Watch for complications such as pulmonary edema from excessive fluid resuscitation
