Monitor an underactive thyroid (hypothyroidism)

Monitor and improve your thyroid function with a home blood test, personalised insights, and GP advice.

What is an underactive thyroid?

Your thyroid gland produces hormones that help control your metabolism. These hormones are:

  • thyroxine (T4)
  • triiodothyronine (T3)

If your thyroid gland doesn’t produce enough of these hormones, it’s called hypothyroidism (or an underactive thyroid).

Symptoms of an underactive thyroid

The lack of thyroid hormones can “slow down” many of your bodily processes. This can lead to symptoms like:

  • weight gain
  • extreme tiredness
  • irregular periods with heavy bleeding
  • brittle hair or hair loss
  • difficulty concentrating
  • low mood
Thriva home blood testing kit and health results on smartphone
Thriva blood tests accurate testing, doctor's report, evidence-based advice

Monitor an underactive thyroid with a blood test

A blood test can measure your thyroid hormone levels to see if it’s underactive. It can also check to see if you’re getting the nutrients you need to support your thyroid function.

Arrow

Thyroid hormones

Thyroid hormones include T3 and T4. Another important hormone is thyroid-stimulating hormones (TSH) — this controls the production of T3 and T4. If your thyroid gland is underactive, your T3 and T4 levels drop. While your TSH levels increase to try to stimulate your thyroid to produce more hormones. 

Arrow

Thyroid antibodies

Thyroid antibodies can sometimes cause an autoimmune thyroid disease — where your body mistakenly attacks your thyroid gland. If this leads to an underactive thyroid, it’s called autoimmune thyroiditis. These antibodies include thyroid peroxidase antibody (TPO) and thyroglobulin antibody.

Arrow

Vitamin B12

Vitamin B12 plays a key role in the normal functioning of the nervous system, and the formation of red blood cells. Vitamin B12 deficiency is commonly seen in people with an underactive thyroid. And increasing your levels might help to improve symptoms.

Arrow

Folate

Folate (vitamin B9) is needed for a healthy liver, as well as healthy skin, hair, and eyes. An underactive thyroid has been linked to lower folate levels. If you’re deficient, symptoms include feeling tired, pins and needles, and shortness of breath.

Arrow

Vitamin D

Vitamin D deficiency is linked to thyroid disorders. Some research suggests that low vitamin D levels can affect your immune function, which could increase your risk of an autoimmune thyroid disorder developing. A deficiency is also linked to tiredness, low mood, bone and muscle pain, as well as getting ill more often than usual.

Arrow

Iron

If your iron levels are low it might affect your thyroid function. Some research suggests it can increase your risk of developing an underactive thyroid. It’s also thought that an underactive thyroid might contribute to iron deficiency anaemia.

Arrow

HbA1c

An underactive thyroid has been linked to high blood glucose (sugar) levels — which can affect your risk of type 2 diabetes. A HbA1c test measures your average blood glucose levels over the last 3 months.

Arrow

Cholesterol

An underactive thyroid might make your body less effective at removing LDL cholesterol — the type of cholesterol that can increase your risk of heart disease. So it’s worth monitoring your cholesterol over time to help manage your risk.

Your health journey

Health goals

Order your home blood test

Answer a few questions and start building your personalised test package. We'll post your kit the next working day.

See all blood tests
Get results in 48 hours

Get results in 48 hours

Your kit contains everything you need to do your test and post your sample. Your results and GP report will be available online.

See how to do your test
Get personalised support

Get personalised support

Discover the best evidence-based ways to improve your health. Access recipes, supplements, and more to build lifelong healthy habits.

What's a health plan?
Track and improve your health

Track and improve your health

Understand your body, learn what works for you, and stay on top of your health.

The science of tracking

Emma's plan

Emma has an underactive thyroid and wants to monitor her condition. She tracks her thyroid function and checks for any nutrient deficiencies linked to her condition.

Your sample will be analysed by a CQC-registered and UKAS accredited lab. This finger-prick test and kit are CE-marked.

Your sample will be analysed by a CQC-registered and UKAS accredited lab. This finger-prick test and kit are CE-marked.

Want to monitor your thyroid function?

Get more insights to your health with a home blood test.

Related articles

Article about your thyroid gland
Podcast about how food affects your mental health
Article about the causes of vitamin D deficiency
illustration

Data protection

Your data is in safe hands. We use the latest encryption technologies and comply with the UK Data Protection Act 2018.

See privacy policy
Illustration graph

Accuracy

Our blood testing kits are CE-marked, and we work with UKAS accredited labs who are registered with the CQC.

See labs and accuracy