Can I Go Back To Normal Water Intake Or Is There A Risk Of Brain Swelling? May Have Polydipsia.

Posted on Mon, 1 Oct 2012

Question: I'm a biologist, so I know a bit about science. I might have been hypernatremic for 2 days. I was told that I might have polydipsia, so I reduced my water intake to 70 ounces of water and about 500 to 2000 milligrams of sodium on Thursday and 120 ounces of water and 1000 mg of sodium on Friday (yesterday). I was thirsty after a meal for hours, because I didn't drink more than 5 and a half ounces of water per hour. Even though I was thirsty, my urine was often clear. Also there were periods of several hours a day when I was not thirsty. So maybe I was not hypernatremic throughout the 48 hours. Can I go back to my normal water intake while eating 2000 mg of sodium, or could there be a risk of brain swelling? If you have been hypernatremic for 2 days the brain takes in organic osmolytes to adjust to hypernatremia, and if you then decrease the blood sodium level by more than 0.5 mEq/L per hour you can develop brain swelling. I sometimes have a small neurological symptom - a visual disturbance for half a second. But it goes away. I am now drinking 5 and a half ounces of water every half hour as I am thirsty. I am not eating any salt. I calculated that my blood should not be altered by more than 4 ounces of fluid per hour. Does drinking 11 ounces of fluid per hour without eating any salt (which might reduce the amount of urine produced) lead to more than 4 ounces of fluid being retained? Should I eat some salt? But if I do I will have to drink a great deal and will then there is the possibility that the blood sodium level might drop too fast. I would probably have to drink 20 ounces per hour if I eat salty food. I thought that if I keep my blood sodium level consistently below 145 mEq the brain adaptation to hypernatremia would be reversed. However, if I continue to drink 11 ounces of water per hour and don't have any salt intake today, I could become hypnatremic because the kidneys have a lower limit of water excretion when you eat less salt. I was thirsty, so I drank 11 ounces per hour. Also, I didn't want to continue to keep my blood sodium level at or above 145 mEq. What should I do?

Answered by Dr. Avinash Ignatius (12 hours later)

Hi,

Thanks for your query.

Hypernatremia although is a measure of the amount of salt in the serum. It is an indicator of water imbalance - Excess water in the body causes dilution and hyponatremia and whereas a water deficit. Usually extremes of sodium levels do not occur in normal persons due the existing thirst mechanisms.

I don't see any of your sodium levels reported here. It would be essential to first identify whether hypernatremia exists, if so the severity of it. Meanwhile continue your usual salt and water intake, rather than going by assumptions.

If your sodium turns out to be high, check your serum osmolality and urine osmolality.

Hope I have answered your query. Please accept my answer in case you do not have further queries.

Above answer was peer-reviewed by : Dr. Raju A.T

Follow up: Dr. Avinash Ignatius (8 hours later)

Hi Dr. XXXXXXX

My blood sodium level was checked 2 and a half days ago and at that point in time it was normal. I have developed a problem now with my kidneys. About 24 hours ago I started to get kidney pain. This could be because for about a week and a half I did not drink water fast enough when I was thirsty, because I was told that I might have polydipsia. Sometimes I was drinking only 5 and a half ounces every hour. And there were times when I was dehydrated, because my urine was dark - but this didn't happen often. Most of the time my urine was clear. Can I now go back to drinking and eating normally or might the kidneys be damaged (I have kidney pain)? In that case if I drink normally and the kidneys don't filter the water fast enough I could develop hyponatremia. Please tell me if it is okay for me to go back to drinking whenever I feel thirsty - I usually drink 15 ounces an hour after a salty meal for a while and then don't need to drink for some time. Thank you for your advice.

Answered by Dr. Avinash Ignatius (10 hours later)

Hello.

Thanks for reverting back.

Kidneys do not pain due to dehydration or hypernatremia. If it is truly kidney pain you need an ultrasound.
Intake of 15 onces of water every hour is quite high. If we exclude 8 hrs of sleep, you would still be consuming 8 liters of water in the remaining 16hrs. When the intake of water is so high the kidneys adapt themselves to excrete all this excess water.

If you suddenly try to reduce your water intake or for whatever reason are unable to maintain the present intake, your kidneys which are tuned to producing a large amount of urine continue to produce this excess amount of urine, leading to dehydration.

Ideally you need to undergo a water deprivation test in a hospital setting, with monitoring of your urine output, weight, serum osmolality and urine osmolality.
Possibilities of diabetes insipidus / dipsogenic polydipsia have to be considered or it could be just because of habit.

Keeping a strict record of your fluid intake and try gradual reduction of the fluid consumed over a period of weeks. (try only 13 onces / hr reduce to 12 ounces / hr next week).

Hope, this answers your query. Please accept my answer in case you do not have followup queries.

Wish you good health.

Regards.

Above answer was peer-reviewed by : Dr. Jyoti Patil

Follow up: Dr. Avinash Ignatius (55 minutes later)

I have another question - for two days I drank 100 ounces of water on the first day and 112 ounces of water on the second day, but only ate 300 mg of sodium on the first day and 600 mg of sodium on the second day. Could I have been hyponatremic for 2 days? Could I return to my normal diet of about 2000 mg of sodium per day, or could that cause central pontine myelinolysis? I was having some symptoms after drinking 6 ounces of water every half hour, after eating a meal - some jerking movements and a very slight visual disturbance, which went away after a few seconds.

Answered by Dr. Avinash Ignatius (22 hours later)

Hello.

Thanks for follow up query.

It is fine to continue your usual intake of salt and water. It won't cause such a change in serum sodium to induce CPM (Central pontine Myelinolysis).

Just gradually try to cut down on your fluid intake, over the next few weeks. If you are unable to reduce due to thirst, you will need detailed assessment by a Nephrologist with the tests mentioned earlier.

Hope, this answers your query. Please accept my answer in case you have no further queries.

Regards.

Above answer was peer-reviewed by : Dr. Jyoti Patil

Follow up: Dr. Avinash Ignatius (20 hours later)

I might have been hyponatremic for two or three days (I drank a lot of water and was on a low sodium diet) and I then had a 12 hour period where I only drank 15 ounces of water (I didn't drink much before going to bed, and then I was asleep. When I woke up my urine was very dark and I was thirsty.) Could there have been a rapid shift in my blood sodium level? Could I develop central pontine myelinolysis? Or does that only happen when an IV is used to correct hyponatremia? Please note that during the three days I did have periods of time where my urine was dark, so maybe I wasn't hyponatremic from drinking too much water, as I might not not have had an excess of water in my system. My blood pressure is normal, so I'm probably not hypovolemic. By the way, do you know how many milligrams of sodium is 300 milliosmoles/d? If you have a sodium or total solute intake of 300 milliosmoles/d, the kidneys can excrete 4 liters of water per day. Is it true that low sodium intake can lead to less blood volume, which can lead to dilution of the blood and hyponatremia?

Answered by Dr. Avinash Ignatius (16 hours later)

Hello XXXXXXX

Thanks for follow up query.

Amount of sodium consumed is ideally quantified in either mEq or mg. (Milliosmoles is a term conventionally used when a substance is being an active solute form.)
Sodium is always consumed as some form of salt with another anion, like sodium chloride(common table salt). So if you consume 300 mEq of sodium you are also taking in 300 mEq of chloride. 58.5 mg of table salt would provide you with 1 mEq of Na and 1 mEq of Cl. For 300 mEq of sodium you would be consuming about 20 -21 gms of salt every day.

Sodium is additionally present in almost in all foods that are consumed in varied amounts, which needs to be factored in. Also urinary excretion of sodium has a very wide range from less than 20meq/L to more than 250meq/L, depending on the state of your hydration, salt intake, serum sodium and any medications.

In a normal person, even a salt free diet will not cause any problems, as the sodium content of food is adequate for our daily needs. There is no reason to justify the statement 'that low sodium intake can lead to less blood volume, which can lead to dilution of the blood and hyponatremia' in a normally healthy person.

You are unlikely to have myelinolysis - only an MRI with diffusion weighted images can confirm that.

Diagnosing and managing electrolyte disturbances can't be based on presumptions and conjectures, you need to have hard evidence in your labs. If problems persist consult a physician/nephrologist in person.

Hope, this answers your query. Please accept my answer in case you have no further queries.

Regards.

Above answer was peer-reviewed by : Dr. Yogesh D

Follow up: Dr. Avinash Ignatius (2 days later)

Thank you for your reply. I have a question about my kidney function. I have been unable to quench my thirst for two weeks, because I was told I have polydipsia. So I reduced my water intake to 5 and a half or 6 ounces every half hour and then to 5 or 6 ounces every hour. But there have been times where I have drunk 6 ounces every half hour, and then waited till my clear urine became yellow again to drink. This meant that there were periods of time where I drank less water because I was waiting for my urine to become concentrated - but then in the time I was waiting for that I became dehydrated. In one instance there was a period of 14 hours where I drank only 15 ounces of water. Could I have harmed my kidneys? But on the whole I was usually drinking about 100 ounces in a 24 hour period (though sometimes 80 ounces). I also reduced my sodium intake. Today in the morning I was dehydrated so I drank 30 ounces of water over a 3 and a half hour period, from 7:30 AM to 11 AM. I did not start urinating until 11 AM. Does that mean that my kidneys were not functioning properly, or does it simply mean that my body needed the water as I was dehydrated? I noticed that my kidneys were still able to produce 6 ounces of urine every half hour, if that was what I drank. If I drank 6 ounces every hour, they produced 6 ounces every hour. But I have noticed today for the first time that my kidneys seem to be slow to react to changes in my water intake. I want to slowly return to my previous pattern of drinking, which was to eat 2000 mg of sodium and drink maybe 200 ounces of water. Should I first eat 1200 mg of sodium and drink 120 ounces of water and then return to my previous intake of water? Is it safe for me to return to my previous intake of water, will my kidneys be able to deal with the greater amount of water if they are reacting more slowly? But they still are able to produce 6 ounces of urine every half hour.

Answered by Dr. Avinash Ignatius (25 hours later)

Hello,

Thanks for writing back.

You will not suffer any problem if you don't pass urine for even 6-8 hrs. Normally urinary bladder has a capacity of 300 to 500 ml (10 - 18 ounces) before there a sensation to pass urine, some may even have higher capacities before they have the urge to pass urine.

Passing urine 4 -5 times a day is usually enough if your intake of fluid is normal 50 to 80 ounces a day. You will not feel the urge to pass urine till your bladder is full, though your kidneys are normal. For monitoring hour by hour you will need an indwelling urinary catheter, which is neither practical nor recommended.

And yes, as I said earlier, excess intake of water has reduced your kidney's capacity to adjust to reduction in fluid intake. It will take a couple of weeks to improve. You will also have to tolerate some amount of thirst to allow your body to readjust.

Hope I answered all your questions. Please accept my answer in case you do not have further queries. Wish you Good Health.

Regards,

Note: For further queries related to kidney problems and comprehensive renal care, talk to a Nephrologist. Click here to Book a Consultation.

Above answer was peer-reviewed by : Dr. Shanthi.E