Thyroid UK
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Newly diagnosed

After 2 years of sub clinical symptom, I have recently been diagnosed as hypothyroid by a new GP. I am 53 and lots of my symptoms had been put down to the menopause. He seems very good and was prepared to ignore an endocrinologist's opinion that my thyroid was fine. He asked for new tests (something to do with different labs) and has started me on 50mg levothyroxine. I also have very high cholesterol and low vitamin D. I am now due for more blood tests - he has asked for TSH, renal profile, LFTs & FBC - I have no idea what these are and how they relate to my thyroid. My questions are

1) Is this a normal/full range of tests and what are they?

2) what questions should I be asking at my next appt?

3) what supplements should I be taking and when?

4) has anyone had any success losing weight - I have put on 3stone over the last 2 years :(

Thank you.

6 Replies

Welcome to the forum, Vm133.

TSH is a pituitary hormone. TSH responds to thyroid hormone levels (T4 and T3). When the pituitary gland detects low T4 and T3 additional TSH is produced to stimulate more thyroid hormone so TSH rises. When sufficient T4 and T3 is detected TSH drops.

Thyroid is a sort of master gland affecting many organs. Hypothyroidism can reduce function of liver, kidneys and heart which is why your GP is checking kidney and liver function and FBC. This link explains what a FBC is Cholesterol is often high in undiagnosed and under medicated thyroid patients. It should come down when you are optimally medicated on Levothyroxine.

Ask your GP to check ferritin, B12 and folate as these are often low/deficient in hypothyroid patients. Post the results and ranges (figures in brackets after results) in a new question for advice on whether to supplement. You could also ask your GP to test thyroid peroxidase antibodies to see whether your hypothyroidism is autoimmune.

What is your vitaming D result?

After every blood test ask your GP or GP receptionist for a copy of your results with the lab ref ranges.

Now you are having low thyroid hormone replaced with Levothyroxine you may find that weight gain slows down. You may need to restrict calories and exercise to lose the weight already gained but you should delay doing either until you are optimally medicated.

For maximum absorption Levothyroxine should be taken with water 1 hour before or 2 hours after food and drink, 2 hours away from other medication and supplements, and 4 hours away from calcium, iron, vitamin D supplements and oestrogen.

It takes 7-10 days for Levothyroxine to be absorbed before it starts working and it will take up to six weeks to feel the full impact of the dose.

You should have a follow up thyroid test 6-8 weeks after starting Levothyroxine. Arrange an early morning and fasting (water only) blood draw when TSH is highest, and take Levothyroxine after your blood draw.

Most people will find symptoms resolve after their TSH drops to around 1.0 with FT4 in the upper range but symptoms can lag a couple of months behind good biochemistry.


I am not a medical professional and this information is not intended to be a substitute for medical guidance from your own doctor. Please check with your personal physician before applying any of these suggestions.


Thank you that is all really informative.

Can I ask why I shouldn't diet til my levels improve? At the moment I am too tired to consider additional exercise so that won't be an issue



There's no point. If the weight is going on because thyroid levels are low dieting and exercising won't help until you have sufficient thyroid levels. Exercise will further deplete T3 levels and exacerbate fatigue.


High cholesterol and unexplained weight gain are two of the 300+ clinical symptoms of hypothyroidism (we don't get all of them thankfully :)

You should begin to feel better when they increase your dose to an optimum level, i.e. symptoms relieved and you feel well.


FBC is a full blood count. Looks at number of white cells plus percentage of type, number of red cells plus some red cell measurements and number of platelets in your blood.

Renal Profile and LFT (liver function tests) looks at different chemicals, proteins and enzymes in the blood such as sodium, calcium, alkaline phosphatase (ALP) , bilrubin and gamma-glutamyl transferase (Gamma GT or GGT).

The reason for the tests is to confirm or disapprove that you have other problems. For example lots of women have low iron levels however their haemoglobin level is in the NHS lab range. If these women also have average small sized red blood cells and a low white cell count then the doctor would likely think they could have iron deficiency anaemia.


Thanks - I obviously have a lot to learn and from what I've experienced and read so far it is clear that lots of doctors are not fully informed.

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