kidney question

[roohani.doctor]

salam pples,

Got a question. Help would be GREATLY appreciated.

If one were to consume a bicarbonated drink (e.g. juice flavoured solution (with 3% sodium bicarbonate) but no sugar etc), how would it affect the urine volume produced? And urine production rate.

I have googled this but all I can see is how it affects the pH. In the lab I did, the urine volume and the production rate had no trends. They went up and down at random. So I am now confused.

Please help. Have a lab report due in two days.

Jazaka'allah khairan much.

Wasalam.

[جوري]

The question is essentially asking you for the effects of hypertonic saline:

Hypertonic saline 3% has an osmolality (about 900 mosm/l) three times that of plasma. The fluid shifts & osmolar changes that occur with its infusion can be predicted.
Water crosses cell membranes easily and distributes passively in response to osmolar gradients. The Na+ content of the fluid limits the distribution of the infused fluid to the ECF. The hypertonic solution will also draw water out of cells decreasing intracellular fluid volume.
As an example, consider a rapid infusion of 1,000 mls of 3% saline into a 70kg subject with a total body water of 42 liters (ICF: 23 litres, ECF: 19 litres).
Just Before the infusion:Total body solute content = 42 x 290 = 12,180 mOsm.
ECF solute content = 19 x 290 = 5,510 mOsm
ICF solute content = 23 x 290 = 6,670 mOsm.
Immediately After the infusion :Total body water = 42 + 1 = 43 liters
Total body solute content = 12,180 + 900 = 13,080 mOsm.
ECF solute content = 5,510 + 900 = 6,410 mOsm
ICF solute content = 6,670 mOsm (ie unchanged)
The prediction is:
Final osmolality = 13,080 / 43 = 304 mOsm/l
ECF volume = 6,410 / 304 = 21.1 litres.
ICF volume = 6,670 / 304 = 21.9 litres.
Is the increase in osmolality enough to be sensed by the osmoreceptors?
Yes. The increase in ECF volume is 2.1 litres with about a quarter of this (say 500 mls) intravascularly. Plasma osmolality has increased by 4.8% and this is well above the threshold (1 to 2%) of the hypothalamic osmoreceptors.
Is the increase in blood volume enough to be sensed by the low pressure (volume) baroreceptors?
Yes. The blood volume has increased by about 10%. The volume receptors respond to changes above about 7 to 10%.
The increase in osmolality will be sensed by the osmoreceptors in the hypothalamus and this will be a potent stimulus to the secretion of ADH to retain water in the kidneys. Thirst will also be increased. The increase in blood volume is at about the lower level of sensitivity of the volume receptors. The effect via the volume receptors will be to inhibit ADH secretion to allow water excretion. In general, volume stimuli tend to be less sensitive but more potent than osmotic stimuli.
There will also be effects on Na+ excretion. The volume expansion will stimulate secretion of atrial natriuretic factor (ANF). Secretion of aldosterone will be inhibited because of a decreased renin and angiotensin II production. ANF also inhibits renin secretion.
The final outcome of all these changes is natriuresis and excretion of the excess water. The increased osmolality causes an increased ADH and this will tend to inhibit the rate of excretion of the excess water.
The decrease in ICF volume may have effects on the brain causing confusion and mental obtundation due to cerebral cellular dehydration and hypertonicity. These effects on cerebral function will probably be the predominant clinical effects. The function of other organs or tissues in unlikely to be significantly affected.
The increase in ISF volume is not sufficient to cause oedema or interfere with gas transfer or nutrient and waste transfers between cells and capillaries.


http://www.anaesthesiamcq.com/FluidBook/fl8_2.php


hope this is of help to you insha'Allah

:w:

[جوري]

you need to understand that the urine output in a normal subject primarily reflects water intake, which leads to alterations in the plasma osmolality that are sensed by the osmoreceptors in the hypothalamus that regulate both ADH release and thirst. As an example, an increase in water intake sequentially lowers the plasma osmolality, decreases ADH secretion, and reduces collecting tubule permeability to water; as a result, the excess water is rapidly excreted in a dilute urine.. I hope that makes it very clear for you without me having to actually do your homework just for honesty' sake :D


let us know how well you do insha'Allah

:w:

[roohani.doctor]

Thanks mucho for your rapid replies. Very informative. :wub:

But am I to understand that hypertonic saline is essentially gonna give the same results as hypertonic bicarb solution? i.e. both will lead to hypernatraemia, i.e. dehydartion and therefore more water will be reabsorbed back into the body leading to a concentrated urine? non?

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[roohani.doctor]

One more thing --> what role does BICARBONATE have in all this..it causes alkalosis ... but how does that affect urine volume? Does it decrease or increase it?

[جوري]

:sl:

No sodium chloride and sodium bicarbonate AREN'T the same thing, however these electrolytes dissociate in plasma and you'll have to look at sodium Na+ (effect) separately (see above) you can safely conclude what you have written but it depends on the amount since Sodium bicarbonate balanced is what you drink in regular soda pop, and look at the effects of bicarbonate Hco3- separately..
bicarb is used to transport dissolved carbon dioxide in plasma and enhance water absorption from the brush border of the villi of the small intestine, when added to sodium it has no effect on water absorption and sodium does all the work, if there is glucose in the above solution then that would also enhance the sodium absorption, the bicarbonate part will make the stomach content more alkali..

now we have uses for alkali solution in medicine and outside of the realm that I have just covered (basic physio) we use it in metabolic acidosis, chronic renal failure, urine alkanization in some cases of aspirin poisoning, renal tubular acidosis Prevention of contrast-induced nephropathy..

I don't know if that answers your question? I hope it does insha'Allah..

it is rather late here 3am and possible I'll regret all of this tomorrow, but hope on some level it makes sense :lol:

:w:

[roohani.doctor]

aww thank you again! Yep its 3.05am here as well. This is due in two days but I wana finish it today and then go over it again tom...its worth 20% of me mark so i cant afford carelessness...

yes it makes sense and it answers my question. I'm gonna back and write it now. I'm pretty much done the research for now.

I might have a couple of questions tomorrow though (later on today actually).

You are awesome sis. Very knowledgeable. *thumbs up*

Jazakallak khairan, May Allah bless you. Ameen.

[جوري]

really al7mdlilah.. until I can reflect more on this tomorrow, just address the sodium and bicarbonate separately in plasma for all intensive purposes 3% Na+ is hypertonic and will exert its work alone, but I'd back up all I said from some source, since I only wrote from memory and I have done acid/base and electrolyte physiology so long ago I am embarrassed to admit to how far back lol...

good luck on your homework insha'Allah

:w:

[roohani.doctor]

one more question --> what does chloride clearance mean exactly?

For my results:

The control group - who drank no liquids thru the exp duration (about three hours) had the highest rate of clearance
Distilled water
Bicarbonate (3%)
Cola (12% sugar solution)
NaCl (2.7%) - least chloride clearance

This makes no sense to me as I would think NaCl to have the highest clearance cuz you are ingesting excess Cl.

:S *confused*

[جوري]

I can only discuss chloride clearance from a medical stand point so I am not sure it will be of help to you?



In most clinical states, sodium and chloride excretion vary in parallel [1] . When used to assess volume status, for example, both are typically less than 15 meq/L with hypovolemia and greater than 20 meq/L with euvolemia or volume expansion.

However, as many as 30 percent of volume depleted patients have more than a 15 meq/L difference between the sodium and chloride concentrations in the urine [1] . This may be due to the excretion of sodium with another anion (such as bicarbonate or carbenicillin) or of chloride with another cation, such as ammonium in metabolic acidosis. (See "Urine anion and osmolal gaps in metabolic acidosis").

As a result, it may be helpful to measure the urine chloride concentration in a patient who appears to be hypovolemic but has a higher than expected urine sodium. This most often occurs in metabolic alkalosis due to vomiting. In this setting, the desire to excrete the excess bicarbonate (as NaHCO3) to correct the alkalosis may lead to a high urine sodium concentration despite the presence of volume depletion (show table 1) [1,2] .

In contrast, there is no stimulus to chloride wasting; as a result, the urine chloride concentration will be appropriately low, reflecting both the true volume status and the associated hypochloremia. The possibility of bicarbonate-induced sodium-wasting can be detected simply by measuring the urine pH: a value above 7.0 suggests significant bicarbonaturia and the probable need to measure the urine chloride, whereas a value below 6.5 indicates that there is little bicarbonate in the urine and that the urine sodium concentration alone should be accurate (assuming that some other unmeasured anion is not present). (See "Urine electrolytes in diagnosis of metabolic alkalosis").

The dissociation between urinary sodium and chloride occurs in the opposite direction in metabolic acidosis. In this setting, ammonium excretion is physiologically increased in an attempt to excrete the excess acid. The net effect is that, in a hypovolemic patient with diarrhea, the urine sodium concentration is appropriately low but the excess urinary ammonium will obligate an increase in the urine chloride concentration [3] .


Use of UpToDate is subject to the Subscription and License Agreement. REFERENCES
Sherman, RA, Eisinger, RP. The use (and misuse) of urinary sodium and chloride measurements. JAMA 1982; 247:3121. Kassirer, JP, Schwartz, WB. The response of normal man to selective depletion of hydrochloric acid. Factors in the genesis of persistent gastric alkalosis. Am J Med 1966; 40:10. Kamel, KS, Ethier, JH, Richardson, RM, et al. Urine electrolytes and osmolality: When and how to use them. Am J Nephrol 1990; 10:89.

[جوري]

how did it go sister? Hope all went well insha'Allah...

:w:

[roohani.doctor]

hello sister! :D Yes I've been meaning to post here for a while.

It went well ALHUMDULLILLAH.......I had to pull an all nighter but it paid off well.

Much thanks to you for the site you provided above as well as the journal at the end. It helped mucho!

The chloride clearance stuff was a little confusing and much too detailed for what they were looking for but the reference for it gave some other useful info that I used.

I'm getting the marks back next week so will let you know it went.

Seriously sis jazaka'allah khair x a million for your help. May Allah bless you infinitely. Ameen.

:wub:

[جوري]

ah man, I hate waiting for results.. I'll keep you in my thoughts and prayers insha'Allah..

:w: