Urinary Elimination Questions

[SA2BDOCTOR]

What is the minimum amount of hourly urine production is necessary to maintain kidney function? Why is this parameter mportant in ill or post operative clients?

I am not certain as to the exact amout, what I do know is that less than 30ml is cause to worry.

Please advise

[Daytonite, BSN, RN]

could not find a minimum hourly rate stated in any of my references, but did find evidence to indicate that along with the amount of water being excreted, it is also important to know if there is any interference with these mechanisms since they will affect the final urine volume that is formed:

1. glomerular filtration
   
2. tubular reabsorption
   
3. tubular secretion

"a urine volume less than 30 ml/hr in an adult is cause for concern if it persists. one must be constantly aware that persistent oliguria in the severely volume-depleted patient can result in renal tubular damage." (page 43, fluid & electrolyte balance: nursing considerations, 4th edition, by norma m. metheny).

"normal urine output averages about 1 ml/kg body weight/hour, or approximately 1500 ml in a 24-hour period in a healthy adult. the urine output can be as small as 1000 ml or as great as 2000 ml in a 24-hour period, which is an average of approximately 40-80 ml/hour in a healthy adult. children have lesser amounts of urine volume, based on their age and weight. when the body is under stress, urine output may be less than normal because of increased aldosterose and antidiuretic hormone secretion. . .low or high urine volumes may indicate a fluid imbalance. urine osmolality and specific gravity give further information on this issue. . . .this value depends on the amount of antidiuretic hormone that is in the blood stream and the rate that solutes are excreted through the kidneys. . .on average, urine osmolality should be approximately 1.5 times that of the serum osmolality. . .it is important to understand and discriminate between the differences in water diuresis and solute diuresis. a low urinary specific gravity, a low urinary osmolality, and a normal or elevated serum sodium level can indicate either a lack of antidiuretic hormone or the inability of the renal tubules to respond properly. these findings indicate water diuresis. solute diuresis occurs when impaired tubular absorption of a solute occurs. symptoms of solute diuresis are a high urinary specific gravity, a high urinary osmolality, and a normal or low serum sodium level. solute diuresis may occur in such states as diabetes mellitus or the correction of bladder obstruction. . .based on this. . .it is apparent that the amount of solute and the amount of waste product in the urine can influence volume. in other words, urine volume would be increased in conditions that cause high levels of solute in the urine. the amount of circulating volume in the extracellular space also affects urine volume. hypovolemia can result in decreased urinary output. hypervolemia can cause increased urinary output in the presence of normal renal function." (page 361, intravenous therapy: clinical principles and practice, by judy terry, leslie baranowski, rose anne lonsway and carolyn hedrick, published by the intravenous nurses society, 1995).

[Achoo!, LPN]

We are told to report if it is less than 30 cc/hr.

[allthingsbright]

30 ml/hr is the norm

oliguria is 400 ml or less in 24 hr

anuria is 50 ml or less in 24 hrs

good luck!

[somberhue]

i think i read 1ml/kg/hr... on p. 252 of Medical surdical nursing by smeltzer and bare, it is said that the general rule is that the normal urine output is approximately 1ml of urine per hilogram os bodu weight per hour... (1ml/kg/hr)

hope it helps!!!

[ALEXIS VALIENTE]

i think i read 1ml/kg/hr... on p. 252 of Medical surdical nursing by smeltzer and bare, it is said that the general rule is that the normal urine output is approximately 1ml of urine per hilogram os bodu weight per hour... (1ml/kg/hr)

hope it helps!!!

very right~!!!!

[al7139, ASN, RN]

To the second part of your question:

Why is it important in post operative and ill pts?

In sick patients, low urinary output can be a sign of renal insufficiency, and can also be an indicator of cardiac problems. 1ml/kg/hr is the norm. Most people produce more than that. If any pt is not producing 30ml/hr or greater it is cause for concern. As a nurse I look at disease, history and especially lab values to determine what is going on to cause low output. Are they a CHF pt? Other cardiac issues? Have a UTI? Electrolyte imbalance? There are LOTS of other diseases...

Also keep in mind if the pt is in renal failure, or is receiving dialysis, they will most likely be anuric (no urine production). For these pts, this is the norm, and no cause for alarm. Since dialysis filters out the body's wastes through filtering the blood, the kidneys do not need to produce urine and excrete it.

In post operative pts, urine output shows lots of things. Think about what kind of surgery they have had, what meds they recieved in surgery and what effect surgery has on the body. Consider hydration status (most are NPO prior to sx), age, and medical history. Was their surgery abdominal? Even a laparascopic surgery for gall bladder removal can cause urinary retention. In reality surgery is a trauma to the body. The difference is it is planned rather than a result of an accident or injury. The period of recovery after surgery can also have an impact. Is the pt bedbound? Has a Foley?

As a nurse this is where your knowledge and critical thinking comes into play. You have to be able to out the pieces of the puzzle together to get the big picture and know what to do about it.

Amy