Guest guest Posted November 13, 2001 Report Share Posted November 13, 2001 ***(I, like you, am a patient) Nick*** Hello Shelagh, ***25 mcg of Cytomel is equivalent to 0.100 mcg of thyroxine. 25 mcg 3x per day is equal to 0.300 mcg of thoroxine. Lets say that when your own thyroid was still there.. that it, too, was producing 0.100 mcg of t4/t3 per day. That's 0.400 mcg. ..total per day. You say " roughly 2 weeks " since tt. Fine, but the body wasn't influenced (did not notice) by the loss of the thyroid gland until week 2 following tt. (the reason for this is explained by Dr. Ain in the following REPOSTS) Due to the 6-8 day half-life of thyroxine..at the 2 week post tt moment, you _really_ were only depleted (by effect) by one week's amount of thyroxine. So.. even if _all_ you were taking was 0.25 mcg of Cytomel TWICE a day.. your system was still working with 0.300 mcg of thyroxine-equivalent each day when your body was normally used to only 0.100 mcg. (est.) This is quite a shock/stress to/for the body because, unlike t4 (thorixine) t3 (Cytomel) is direct, main-line, usable, on the spot, available, a very real JOLT/shock to your system. Reasonably speaking.. your doctor should have started you on 0.25 mcg of Cytomel, split into 4 and taken at 3 to 4 hr intervals and then to have you tell him how you were doing. If you were feeling no ill effects from 0.25 mcg (Cytomel) but weren't feeling normal.. and felt that more was needed.. he could have prescribed additional t3 which you then could have spaced apart every 2 hours or so. None of which would have stressed your system as may be the case, at present. When we think of prescription medicine.. we are speaking of a dosage amounts relative to a 24 hour-day. And I don't think that you're getting up in the middle of the night in order to take your last dose. So this means that the dosage-taking period is closer to 16 hours then it is to the whole 24 thereby making your circumstance even _more severe_ then even first glance would indicate. (way too much med.) The effect of the stress of too much t4/t3 can be very damaging to the heart. With Cytomel.. less is always safer/better to start with.. esp. on the way TO going hypo, as your system still has thyroxine left over from your own thyroid gland production.. and will continue to have for the next 4 to 6 weeks. I would not take 0.75 mcg of Cytomel, _ever_ .. in a 24 hour period. No way.. no how.. _never_. Your doctor doesn't understand much about thyroid hormone and it's effects. Tell him I said so. Better yet.. gimme' his address and I'll tell him. Or.. at the very least, show him Dr. Ain's Post's, please :-) Sincerely, Nick ********************************************************************************\ ************************************************************ Levothyroxine (T4) is the major product of the thyroid gland and is essentially a prohormone with minimal (if, debatedly, any) activity of its own. It has a long and stable half-life in the blood (one week) and is transported into cells where it is converted into T3, which directly interacts with receptors which bind DNA and regulate genes. All of this has been well-studied and constitutes a vast medical and molecular biology literature. (Dr. Ain) ********************************************************************************\ ************************************************************ (Dr. Ain # 1 ) Date: Thu, 04 Jan 2001 14:08:49 -0500 Subject: Re: What dosage to start on In-reply-to: >According to Dr. Ain, " the mean replacement dose of levothyroxine is 2.0 >micrograms per kilogram (2.2 lbs) per day " , which would start you off at >100mcg/day. Dear ThyCa Members: Fortunately, I am not often misquoted; however there is a slight error in the quotation above. The mean " replacement dose " of levothyroxine (to obtain a normal TSH 0.5-4.0) is 1.6 micrograms per kilogram per day. The mean " suppression dose " of levothyroxine (to suppress TSH less than 0.1) is 2.0 micrograms per kilogram per day. There is a wide variation in individual patients so that these mean values are only starting approximations for estimating levothyroxine dosages. Following at least 6-8 weeks of such medication, the TSH and free T4 should be checked to see if the suppression target has been reached: TSH < 0.1 while the free T4 not much above the upper normal limit. If a levothyroxine dosage needs to be changed, then another 6-8 weeks must be waited before checking the labs again. **************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, Room MN524 University of Kentucky Medical Center 800 Rose Street, Lexington, Kentucky 40536-0298 ********************************************************************************\ ************************************************************** & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & (Dr. Ain # 2 ) Date: Tue, 07 Nov 2000 11:22:54 -0500 Subject: Cytomel Dosing for Scan/I-131 Prep In-reply-to: >Dear Ellen - > >Are you sure about the Cytomel - 50 mg twice a day??? Unless I'm mistaken, that's equivalent to 400 mcg Synthroid! Sounds like quite a lot. repost from 10/6/00 Dear ThyCa Members: When Cytomel (L-T3) is used to mollify the discontinuation of levothyroxine, the typical dose is 25 mcg given every 12 hours (total daily dose 50 mcg). Sometimes this creates peaks of L-T3 which cause symptoms, which can be alleviated by splitting the pills and taking 12.5 mcg four times daily (same total dose of 50 mcg). For some patients, particularly those who were on levothyroxine dosages of 112 mcg or less, the optimal Cytomel dose may be 1/2 pill (12.5 mcg) three times daily or sometimes twice daily. Dosages in excess of 50 mcg daily are rarely needed and usually cause thyrotoxic symptoms in patients used to 200 mcg or less of levothyroxine. This Cytomel therapy should be discontinued 2 weeks prior to I-131 scanning, when performing the traditional scan preparation. ********************************************* PLEASE BE ADVISED --- YOU HAVE CHOSEN TO COMMUNICATE VIA AN UNSECURED ELECTRONIC MAIL SYSTEM. ALTHOUGH THE CHANCES ARE NOT KNOWN, THERE IS A POSSIBILITY OF UNAUTHORIZED ACCESS TO THIS MESSAGE. THE CONTENT OF THIS COMMUNICATION MAY BE LIMITED, TO TAKE THIS INTO ACCOUNT. ((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((( B. Ain, M.D. Associate Professor of Internal Medicine Director, Thyroid Nodule & Oncology Clinical Service Division of Endocrinology and Molecular Medicine Department of Internal Medicine, Room MN520 University of Kentucky Medical Center 800 Rose Street, Lexington, Kentucky 40536-0298 Telephone: FAX: email: kbain1@... ))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))) & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & ################################################################################\ #################### (Dr. Ain # 3 ) Date: Sun, 16 Jul 2000 16:02:56 -0500 Subject: Re: Starting meds after RAI In-reply-to: >Hello all, > >Can somebody give me a good reference I can give the nuc med doctor. I spoke >with the nuc med tech Friday. He said they don't have people start back on >meds until after their scan, which is 10 days after receiving RAI. I told >him I started back last time 2 days after RAI. He said if I started back on >meds it would interfere with the uptake. > >HELP! > >Roxanne >dx pap ca with invasion 8/99; TT 9/99; RAI 150 mCi 10/99 (outpatient); >Scan 6/28 TG <0.05 Uptake in thyroid bed. 100 mCi scheduled for 7/28 Off >Levoxyl since 4/30. >, CO >USA Dear ThyCa Members: The information requested above is far from new, in fact, it is ancient. Even in patients with intravenous infusions of levothyroxine supplemented with an initial dose of 500-800 mcg, it takes at least 4 days to lower the TSH by 50% and at least one week to lower the TSH below 30. [Ridgway EC, McCammon JA, Benotti J & Maloof F (1972) Acute metabolic responses in myxedema to large doses of intravenous L-thyroxine. Ann Intern Med 77, 549-555.] Administration of daily intravenous levothyroxine doses of 100 mcg required more than one week to reduce the TSH by 50%. [Ladenson PW, Goldenheim PD, DS, MA & Ridgway EC (1982) Early peripheral responses to intravenous L-thyroxine in primary hypothyroidism. Am J Med 73, 467-474.] Elevated TSH is the mechanism of stimulation of thyroid cancer cells to take up I-131 and the reason for with-holding levothyroxine. There is no longer sufficient I-131 circulating in the bloodstream after 48 hours from swallowing I-131 to contribute to the treatment of the tumor. Also, as shown above, starting levothyroxine does not suppress the TSH significantly for several days. For this reason, I start patients back on their full levothyroxine daily dose at 24 hours after administering their radioactive iodine. This is another example of the " practice of medicine " differing significantly from the " science of medicine. " I strive to make my own practice to be consistent with science and biology, as all physicians should. **************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, Room MN524 University of Kentucky Medical Center 800 Rose Street, Lexington, Kentucky 40536-0298 ################################################################################\ ##################### & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & (Dr. Ain # 4 ) Date: Wed, 05 Jan 2000 20:40:23 -0400 Subject: Re: Resumption of Levothyroxine In-reply-to: >Peggy; >it takes a while for the synthroid to kick back in. >It has something like an 8 day life so on day 1 of >synthroid you kind of have 1/8th and day 2 2/8ths and >by the 8th day (or so) you are finally replacing the >synthroid that is leaving your body from day 1. so if >you started the 17th it would be the 25th before you >were even up to a whole level (and if my math is bad >and its more like 10 days then it would be the 27th) >then since our bodies (unfortunately )are not really >totally logical machines then it takes a while for the >body to say... Dear ThyCa members: The above quote, though well-intentioned, is quite incorrect. The half-life of levothyroxine is 7 days. It takes from 6-8 half-lives, when resuming any medication, for the level of the medication to reach its ultimate steady-state level in the body. For levothyroxine (Synthroid, Levothroid, Levoxyl, etc.), this means that it will take fully 6-8 WEEKS for the levels to come back to normal. When stopping levothyroxine, the curve is identical although reversed. That is why the TSH level does not typically become sufficiently elevated for I-131 scans or therapy until 6 weeks after stopping the medication. **************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, Room MN520 University of Kentucky Medical Center 800 Rose Street, Lexington, Kentucky 40536-0084 & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & & At 11/12/01 03:21 PM, you wrote: >I am not a medical professional but I experienced the same symptoms that soon after the thyroidectomy. I cut back to 50 mg/day and gradually increased up to 75/mg by cutting the pills in half. After about 4 weeks post op I was okay with the dose. I think some of the stored T4 has to get used up out of your body before you can tolerate this much T3-but this is very individual thing. I took the 75/day the day after surgery! I was flying high, dropping everything and having skipped heart beats. I was kinda of scarey. > >Nick will probably repost Dr Ain's dosing schedule for stopping and restarting cytomel(T3). I think the idea is to gradually restart and stop. > >Debbi E > cytomel > > > I am curious about dosage/experience w/ cytomel? Roughly two weeks > ago I had my thyroid and lymph nodes removed, doctor prescribed > Cytomel 25 mcg 3X daily. I am very dizzy and one cup of coffee > resulted in mild hand tremors! Wondering if this sounds familiar - I > have been advised to remain w/ the recommended dose. > Shelagh Quote Link to comment Share on other sites More sharing options...
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