Hashimotos question

[Bluebug3]

Thyroid labs
6/22/2015
Levoxyl/cytomel (100mcg/5mcg)
TSH 0.35 (.36-3.74)
FT3 2.80 (2.18-3.98)
FT4 0.84 (.76-1.46)


4/25/15
Levoxyl/Cytomel (100mcg/5mcg)
TSH 0.04 (.36-3.74)
FT3 3.47 (2.18-3.98)
FT4 1.15 (.76-1.46)

4/4/15
Levoxyl/Cytomel (100mcg/5mcg)
TSH 0.02 (.36-3.74)
FT3 3.56 (2.18-3.98)
FT4 1.23 (.76-1.46)

5/2014
Armour 30mg
TSH 0.66 (0.36-3.74)
FT3 2.90 (2.18-3.98)
FT4 0.90 (0.76-1.46)

Last year i was diagnosed with hypothyroidism/hashimotos
4/4 i was feeling great. Thought i was finally at my optimal dose, i had been on it for 3 months. Then i started feeling off: tired, brain fog, forgetfulness, and lack of sexual desire. Had my labs drawn again and it was obvious my levels had dipped a little, my doctor said i was fine so nothing changed. Had seen my doctor in may for stomach issues which ended up being my gallbladder was infected. While being prepped for surgery the nurse remarked on my low blood pressure. After the surgery another nurse asked if it was normal for me to have low blood pressure. I hoped my sluggish day to day life would end once I recovered but nope. Finally had my labs drawn this week and it was obvious my labs were very low. My levels dropped to where they were last year. Doctor raised my dose to 125mcg.
He said for my height (5'4"), weight (159), gender (female), and age (40) my thyroid only produces 125-150mcg so I'm almost there. He thinks this will be the last increase saying my thyroid is possibly dead now.
Where can i find proof of there being a range of knowing how much your thyroid produces?

[gimel]

The problem with any formula used to estimate the required dosage is that it  does not take into account that people are different and have different optimal levels of thyroid hormone.  The problem with the study that Red Star posted is that the objective was to get the study participants only within the reference ranges for TSH and Free T4.  That doesn't work for many people because the ranges are far too broad, and TSH is too variable to be of any value as a diagnostic when already taking thyroid medication.  

A good thyroid doctor will treat a hypo patient clinically, by testing and adjusting Free T4 and Free T3 as necessary to relieve symptoms, without being constrained by resultant test results.  Symptom relief should be all important, not just test results.  And especially not TSH results.  You can get some good insight from this link written by a good thyroid doctor.  

http://www.hormonerestoration.com/Thyroid.html

For further assurance, I suggest this link to a study in the British Medical Journal.  In the link you can find the following comment.

http://www.bmj.com/content/326/7384/311


"We found no correlations between the different parameters of target tissues and serum TSH. Our findings are in accordance with a cross sectional study showing only a modest correlation between TSH and the percentage of positive hypothyroid symptoms4 and data showing discordant responses between the pituitary and peripheral target tissues in patients treated with L-triiodothyronine.5 We assume that secretion of TSH is driven by maximal stimulation, with no further increase occurring with greater severity of hypothyroidism. Therefore, the biological effects of thyroid hormones at the peripheral tissues—and not TSH concentrations—reflect the clinical severity of hypothyroidism. A judicious initiation of thyroxine treatment should be guided by clinical and metabolic presentation and thyroid hormone concentrations (free thyroxine) and not by serum TSH concentrations."

So, looking at your lab results, it appears that you needed the  increase in  your T4 med.  You also need more T3 med.  The optimal for Free T4 is the middle of the range, at minimum.   Free T3 should be gradually increased as necessary to relieve hypo symptoms.  In addition, since hypo patients are frequently too low in the ranges for Vitamin D, B12 and ferritin, you need to test those also.  Low levels can cause symptoms as well as adversely affect metabolism of thyroid hormone.  D should be about 55-60, B12 in the upper end of its range, and ferritin should be 70 minimum.  You can supplement on your own once you know the current levels.  



Y

[Red_Star]

I haven't seen any info about how much a healthy thyroid gland produces but I did find a study on study predicting how much thyroxine is needed after a total thyroidectomy (thyroid gland removed).

The conclusion of that study* shows the regression equation (levothyroxine dose = bodyweight (in kg) - age + 125) gives a more accurate prediction of initiated levothyroxine dose following total thyroidectomy.

Using both equations listed from the study for your weight/age...

Weight only dosage - 1.6 mcg/kg a day:

1.6 mcg x 72 kg (159 lbs) = 115 mcg.

Regression equation - levothyroxine dose = bodyweight - age + 125:

72 kg - 40 + 125 = 157 mcg.

***

*Predicting thyroxine requirements following total thyroidectomy. Clin Endocrinol (Oxf). 2011 Mar;74(3):384-7.

"Abstract

OBJECTIVE:
Optimal thyroxine replacement following total thyroidectomy is critical to avoid symptoms of hypothyroidism. The aim of this study was to determine the best formula to determine the initiated replacement dose of levothyroxine immediately following total thyroidectomy.

DESIGN:
Prospective study. All patients were initiated on 100 μg levothyroxine and titrated to within the reference range for TSH and free T4. Correlations to height, weight, age, lean body mass (LBM), body surface area (BSA) and body mass index (BMI) were calculated.

PATIENTS:
One hundred consecutive adult patients underwent total thyroidectomy for non-malignant disease.

MEASUREMENTS:
Comparison between three methods of levothyroxine dose prediction, aiming for a levothyroxine dose correct to within 25 μg of actual dose required.

RESULTS:
Correlations were seen between levothyroxine dose and patient age (r=-0.346, P<0.01), bodyweight (r=0.296, P<0.01), LBM (r=0.312, P<0.01), BSA (r=0.319, P<0.01) and BMI (r=0.172, P<0.05). A regression equation was calculated (predicted levothyroxine dose=[0·943 × bodyweight] + [-1.165 × age] + 125.8), simplified to (levothyroxine dose= bodyweight - age + 125) pragmatically. Initiating patients empirically on 100 μg post-operatively showed that 40% of patients achieved target within 25 μg of their required dose; this increased to 59% when using a weight-only dose calculation (1.6 μg/kg) and to 72% using the simplified regression equation.

CONCLUSIONS:
A simple calculated regression equation gives a more accurate prediction of initiated levothyroxine dose following total thyroidectomy, reducing the need for outpatient attendance for dose titration."