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Thyroid UK
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Synthroid 50 MCG

I've recently started taking two 25 microgram tablets to equal 50 mcg. I did this because the doctor didn't increase the dose. 25 did not do anything. However, after taking the 50 mcg I notice that I get slightly drowsy and relaxed, like i'm on a low dose of the opiate hydrocodone. I feel no difference in mental clarity, or any of my other symptoms. Mainly just feel calmer. Is this a good sign? I've only been on 50 mcgs for about 5 days.

11 Replies


It is still early days & your previous T4 was low so you have room for a dose increase but people medicating higher levels of thyroid hormone that can not be utilised correctly by the body may cause other hormonal imbalances.

You don’t have Hashimotos so I would look into your low iron levels as iron is key for conversion of T4 - T3 which is the active hormone that brings us well being. Low iron levels may decrease deiodinase activity resulting in conversion to reverse T3 (rather than the active hormone) and this could mean you are hypothyroid (with low ferritin) even with good thyroid hormone levels.

You could test FT3 levels to get a clearer view of your thyroid hormone conversion but I would first look into getting Vit B12 & Vit D tested as these are notoriously low in people with low thyroid hormone and required to make meds work & supplementing iron.

Many members supplement Ferrous Fumarate taken with 500mg -1,000mg vitamin C to aid absorption and minimise constipation. You will need to have iron retested in 6 months.


My Ferritin and iron levels were fine. My b12 and D were low like most people with thyroid problems. Supplemented with D but felt no difference even after Labs showed it was normal after a month of use. I discontinued it, it's already starting to decrease, problem is the thyroid. I get irritated because I want to fix the problem and not the appendages of the problem. My t3 is 3.4 pg/mL (america) latest t4 was .96 ng/dL, t3 reverse 15.7 ng/dL (american), My ratio is 21.7.



You advised in a previous post your ferratin was 75 mg/nl (24-336 mg/nl).

Nutrient & iron levels need to be kept optimal as tackling the appendages of the problem will help in fixing the problem.


is 75 low?



Massively ... under a quarter of the way through range. Hypo males should have levels around half way through range or slightly above.

Good iron levels are important as the iron containing enzyme thyroid peroxidase is required to produce thyroid hormones, & is key for T4 - T3 conversion.

Remember ferritin is only the stored iron & a low result could indicate a possible iron deficiency.

Yes, nutrient absorption is commonly inadequate in people with low thyroid hormone usually due to low stomach acid. Therefore, any gut issues need to be addressed to improve absorption levels (nutrients, iron & hormones).


Can I take Iron with Synthroid?



No, iron supplements will bind with thyroid hormone making it inactive.

Take 4 hours apart. Thyroid meds on an empty stomach with only water. Iron sups with Vit C as detailed above.

You are welcome.


I'll give you blood results, could any of these relate to symptoms. By the way, my last iron level was 108 ug/dL

WBC - 4.3 K/uL (4.5-11) Low

RBC - 4.98 M/uL (4.7-6.1)

Hemoglobin - 15.3 g/dL (14-18)

Hematocrit - 44.3% (40-54%)

MCVolume - 89.0 fL (79-100)

MCHemoglobin - 30.7 pg (26-34)

MCHemoglobin concentrate - 34.5 g/dL (30-36)

Red cell Distribution width - 11.6% (11.5-14.5)

Platelet count - 213 K/uL (140-440)

MPV - 10.8 fL (7.2-11.1)

Unsaturated Iron binding - 167 ug/dL (155-355)

Total Iron Binding cap - 275 ug/dL (228-428)

Percent Iron saturation - 39% (11-46%)

My Albumin/globulin ratio is always high

RDW-CV (blood) is always low or at the bottom of the range.


I mean the shortness of breath, RLS, and tinnitus I experience constantly completely fit anemia. Then I look at the blood, (yes as a layperson) and see things are in range and I start to doubt it. I know they're at the lower end of the range. But my symptoms are so severe that I would think they would have to be incredibly low to cause pain like this.


Range on the Iron is 50-212 ug/dL



It must be a good thing if you feel calmer and relaxed but as it takes 7-10 days to absorb an increased dose of Synthroid it may not be due to the increased dose.

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