RAI: TO DRINK OR NOT TO DRINK?

[Guest guest]

Dear All,

I compiled this a while ago, but never posted it; now seems like as good a time

as any to do that.

When it comes to drinking water while radioactive, there seem to be two basic

schools of thought -

1) drink only limited amounts, in order to give the RAI a chance to circulate

through

your body and be fully absorbed by every little thyroid cell, and

2) drink copious amounts in order to flush the radioactivity out of your system

as quickly as possible, in order to minimize unpleasant side effects (and

be released

from the hospital as quickly as possible, coincidentally a great

cost-saving measure ... for THEM!)

The following includes all of the letters from the experts on this subject, that

I'm aware of, which have been posted here over the past several years.

----------------------------------------------------

This first theory is familiar to anyone on the ThyCa listserv, as it has been

posted

frequently and emphatically by Dr. Ain ...

" I typically advise patients (after doses < 250 mCi) to drink ONLY when

thirsty.

It is counterproductive to advise patients to " drink as much water as you can "

because you will diminish the therapeutic effectiveness of the treatment

against thyroid cancer. Attempts to " wash out " the radioiodine are

self-defeating, particularly in the first 48 hours.

" This is because, a significant portion of the effective radioiodine

recirculates

for additional therapeutic uptake into remnant or tumor tissue. Drinking

large quantities of liquid to cause a forced diuresis actually lowers

the effectiveness of the administered radioiodine. Much of the early tumor

dose comes from re-uptake of circulating I-131.

Rapid wash-out of this I-131 results in diminished tumor dose. Generally,

for I-131 doses < 200 mCi, it is most reasonable to drink only when THIRSTY.

" For HIGHER doses, there is value to drinking 8 ounces of liquid every

hour & emptying the bladder every two hours for only the first 8 hours after

treatment (thereafter, drink when thirsty & urinate when needed).

" After doses EXCEEDING 250 mCi, it is advisable to drink 8 oz of

liquid each waking hour and to empty the bladder every two hours, only

for the first day. This is calculated to minimize radiation dose to the

bladder wall and ovaries. Drinking more, or less, actually increases

the radiation dose to these organs. After the first day, drink when

thirsty and urinate when you want. It is quite rare for patients to

require more than 48 hours hospitalization after radioiodine doses under

200 mCi, unless they have kidney problems. " (7/00)

[... and ...]

" It is quite rare for patients to require more than 48 hours hospitalization

after radioiodine doses under 500 mCi, unless they have kidney problems.

" In addition, the kidneys are already mildly and reversibly dysfunctional

from the hypothyroidism and unable to excrete water as well as they

typically do. This is one of the reasons for the puffiness that is noted.

" Drinking large quantities of water puts you at a risk for development

of hyponatremia (low serum sodium level) which, if extreme, could cause

seizures. " (9/00)

**************PLEASE BE ADVISED**********************

THE INFORMATION CONTAINED IN THIS COMMUNICATION IS INTENDED

FOR EDUCATIONAL PURPOSES ONLY. IT IS NOT INTENDED, NOR SHOULD

IT BE CONSTRUED, AS SPECIFIC MEDICAL ADVICE OR DIRECTIONS. ANY

PERSON VIEWING THIS INFORMATION IS ADVISED TO CONSULT THEIR OWN

PHYSICIAN(S) ABOUT ANY MATTER REGARDING THEIR MEDICAL CARE.

*************************************************

B. Ain, M.D.

Associate Professor of Internal Medicine

Director, Thyroid Nodule & Oncology Clinical Service

Director, Thyroid Cancer Research Laboratory

Division of Endocrinology and Molecular Medicine

Department of Internal Medicine

University of Kentucky Medical Center

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In support of the second protocol - ( " drink copiously " ) there is this,

written by an ENT acquaintance:

" Please be cautious about getting [too much sleep] while you are getting

RAI.

I strongly urge people to take lots of fluids while the RAI is circulating in an

effort

to " wash out " salivary glands. A patient of mine fell asleep right after

receiving RAI

and now may have chronic inflammation of those glands. If you need to fight

insomnia before RAI so be it but please be careful DURING RAI.

" There is no great remedy for chronic sialadenitis (chronic inflammation of

the

salivary gland(s)). I'm not advocating not sleeping - I am advocating excessive

hydration to " flush out " the salivary glands. ... . I encourage my patients to

carry

water with them, take sucking candies, massage the gland that hurts (when

appropriate) and apply warm compresses. The natural history of a chronically

inflamed gland is scarring and fibrosis with eventual loss of gland function and

decrease in pain. "

When I sent him Dr. Ain's letter, he responded with ....

" Thanks for the info. I have no scientific data to support my contention

about

hydration - just patient complaints. If recirculation has a beneficial purpose,

clearly

Doctor Ain is correct. Furthermore, he has a large research area involved in

these

studies making him more knowledgeable than I.

However, considering that the added recirculation correlates to poorer salivary

gland

function, it would appear that more uptake is in salivary tissue than thyroid at

this point.

The advice about urination makes no sense to me as urine is a waste product and

once

it reaches the bladder, it is not reabsorbed. Therefore urinating less

frequently by

conscious effort accomplishes nothing more than allowing RAI to sit in your

bladder -

who knows what that does?

" I agree with you whole-heartedly: there must be a happy medium. Since RAI

is used

to wipe out thyroid tissue (not necessarily cancerous tissue) and since

microscopic cancer

has questionable import, I personally would take my chances with good salivary

function

and decreased efficacy of RAI.

" ..... Dr. Ain's research on thyroid physiology goes a lot further than my

hunches and

clinical observations. Ultimately, it is claimed that the efficacy of RAI is

diminished by

" washout " . Recirculation of RAI increases thyroid cell kill according to Dr.

Ain and I have

no evidence or research to refute this, therefore I accept it. However, the goal

is to wipe

out thyroid tissue (normal and cancerous).

" One has to balance the value of added effectiveness against salivary tissue

destruction.

Having been reeducated here I have to admit that as a surgeon, I would want as

much

thyroid tissue as possible to be destroyed. As a person who now treats several

patients

with chronic sialadenitis from RAI, I would rather have healthy salivary glands.

" In short, there must be a common ground. There is something to be said

about letting

RAI sit in your bladder because you haven't had enough water to cause you to

urinate.

Despite Dr. Ain's logical, scientific and healthy advice, I will still encourage

my patients to

drink water based on experience. Again, I have nothing against sleep as long as

the person

is hydrated. The usual caveat is to take the advice of your real life

physicians. "

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Somewhere in between is Ian Adam (UK nuclear safety officer

and frequent contributor to the list):

“After swallowing the RAI it rapidly gets absorbed from the stomach/gut into

the bloodstream (mostly within a couple of hours), BUT it takes much longer to

be taken up into any remaining thyroid tissue. After it is in the blood there

is a

race between the kidneys and the thyroid as to who gets the iodine first.

The race is not a fast one, and about 1/2 to 3/4 is run in the first 24 hours.

“If you have a normal thyroid then the kidneys get about 2/3 of the RAI, the

rest goes into the thyroid.

“A couple of my patients followed this theory and drank too much. They made

themselves nauseous and one needed medical intervention to get her electrolytes

balanced.

“Also, if you flush the iodine out of your system too quickly then it has less

chance of being

taken up in the thyroid - the whole purpose of doing it.

“My advice is to " Drink a little more than you normally do. "

“For someone with little thyroid remaining then almost all will be excreted by

the kidneys.

“Drinking too little does have physiological effects which are not healthy. I

understand

that many people live on the borderline of mild dehydration. In addition, since

the majority

of the surplus RAI is excreted in the first few hours, that is when you are most

likely to

irradiate your ovaries if you keep your bladder full. For this reason it is wise

to drink

enough to make sure that you wake the first night to empty your bladder.

“Drinking too much will flush the RAI to some extent and thereby reduce uptake.

This is a waste. In addition, I had a couple of patients who drank so much that

they

made themselves nauseous. My wording has always been to 'Drink a little more

than you usually do.'

“It is wise to keep the fluids in the salivary glands and the bladder moving,

but

paradoxically, the longer the iodine stays in the bloodstream the more effective

the treatment.

“If you make a conscious effort to flush the RAI out of your body, you are

making a conscious effort to invalidate the treatment.

“There is certainly some value in keeping things moving. You certainly should

not

keep your bladder too full of RAI for too long, but this is quite different from

forcing

fluids like some centers advocate.

“Personally, I would follow my own advice, which is to drink a little more than

I usually do. " (7/00)

[....and ....]

“I'm not a doctor, I was a technician giving RAI to THYCA patients at a UK

hospital

from 1977 to 1985. I learned that experts are only experts at the part of the

subject

that they are experts at, if you can follow that.

“Our doctors were not involved with the RAI process and had only a superficial

understanding of the mechanics. This never stopped them from answering a

question,

though, and sometimes the answers that they gave were completely wrong.

“I used to advise that patients drink 'plenty', but found that some took it to

extremes

and a couple made themselves nauseous by forcing themselves to drink and one

one needed medical intervention to get her electrolytes balanced.

“I now advise that you drink 'a little more than usual', and I consider it wise

to empty

your bladder once or twice the first night after the dose.

“One important reason for drinking is so that you empty your bladder fairly

frequently.

We have had cases of cystitis after the first night which might have been

attributed to

the patient sleeping all night with a bladder full of RAI.” (10/00)

[ .... and, similarly ....]

" I started administering RAI to thyca patients in 1977. I had never heard

of Dr Ain then. The advice here at that time was to 'drink plenty', the

justification was to minimise bladder dose, and indirectly, gonad dose.

" I became interested in the pharmacology and pharmacokinetics of RAI

and studied the subject.

" I am now in absolutely no doubt that forcing fluids is counterproductive

in the first 24-36 hours post RAI, and of dubious value thereafter.

" Some of this advice comes from the (completely erroneous) idea that thyroid

uptake of RAI is fast. It isn't. The thyroid keeps taking iodine out of the

bloodstream as long as there is any RAI there. In real terms, the process is

more or less complete at 24-36 hours but flushing iodine before then WILL

result in reduced uptake.

" I have personally dealt with several patients who chose to drink heavily and

made themselves nauseous as a result.

" My advice for over 20 years has been to 'drink slightly more than you would

usually'. "

(msg # 13639)

Ian Adam

Radiation Safety Officer

The Institute of Cancer Research

Sutton, Surrey England

------------------------------------------------------

" For a variety of reasons - it appears that some medical professionals

treating thyca patients don't always recommend practices that are based

upon science. We patients have to take the time, ask questions and make

sure that we are as informed as possible about our conditions & treatments

so that we do receive appropriate care. That's why this ThyCa list is so

valuable.

" When I first read Dr. Ain's post regarding not drinking gallons of

water after RAI, I reviewed his recommendations with the endo who was

administering my treatment. He agreed completely with Dr. Ain's

recommendations.

" When I checked into my hospital room for RAI there was a HUGE plastic

glass and an even bigger pitcher for water. Less than half an hour after

I took the RAI pills - my nurse was calling by phone & asking if I was

drinking lots of water'. I replied that I was drinking when I was thirsty

but that was it. She got quite rude & said that if I didn't follow

instructions I would be in the hospital a lot longer because I'd be too

radioactive to release. I suggested she contact my endocrinologist who

had admitted me. She did and ten minutes later called back to apologize.

They had been pushing drinking water after RAI for years and never

considered that it could be counter-productive. " - (list member)

(10/00)

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(this is me, , again ...)

So, dear thycan, I am certainly not in a position to advise you on this one.

Though I was weaned (so to speak) on the first theory, I find all three

arguments to be compelling.

This is a decision you will have to make on your own (along with your doctors,

of course).

My only suggestion would be to decide this early on in the process; do not wait

until

you are severely hypo to think about it, because in my experience, that's a time

when

everything and nothing is logical. I wish you the best of luck.

PS: Separate from this issue is the one of eating/chewing/sucking tart foods

in order to keep your salivary glands moving. And I think it's safe to say that

no one

would disagree with the suggestion to begin drinking a lot of water, if not

sooner,

than at 48 hours after RAI ingestion. This will not only help flush remaining

RAI from

your system, but will help keep your saliva thin and flowing.

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Some additional letters from the archives on uptake speed of RAI (Ian) ...

.... http://groups.yahoo.com/group/Thyca/message/21969 ... how long does it take

for RAI to reach the thyroid, and is drinking a lot of water a good idea? (Ian

Adam)

http://groups.yahoo.com/group/Thyca/message/22422 ... understanding the kinetics

of RAI uptake

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