Thyroid T3/T4

Thyroid T3/T4

The thyroid is the body’s thermostat, controlling body temperature, growth rate and energy use. It regulates the rate at which the body uses food and affects the operation of almost all bodily processes and organs. An under-functioning thyroid gland can result in a condition known as hypothyroidism.

Hypothyroidism is thought to be one of the most under-diagnosed conditions in the world today, affecting children, adolescents and adults.

This disorder can produce many diverse symptoms including fatigue, weight gain, depression and constipation. The thyroid gland can also over-secrete thyroid hormones, resulting in hyperthyroidism with symptoms ranging from weight loss and palpitations to anxiety and diarrhoea.

Conditions associated with hypothyroidism

  • Constipation
  • Cold intolerance/ low body temperature
  • Depression
  • Dry, coarse or thick skin
  • Excessive fatigue
  • Goitre – enlarged, swollen and lumpy thyroid
  • Hair loss
  • Headaches (including migraines)
  • Infertility and impotence
  • Low sex drive
  • Menstrual/ menopausal problems
  • Unexplained weight gain or difficulty losing weight


Conditions associated with hyperthyroidism

  • Anxiety
  • Breathlessness
  • Diarrhoea
  • Hair loss
  • Hyperactivity
  • Insomnia
  • Increased perspiration, intolerance to heat
  • Menstrual irregularities
  • Palpitations
  • Protruding eyes
  • Vitiligo
  • Weight loss

T3, T4, T3/T4 ratio.

This sensitive test measures urine levels of the two thyroid hormones T3 and T4 over 24 hours and also reports on the T3:T4 ratio. As this is a more sensitive test, it can be useful in picking up cases that are classed as subclinical hypothyroidism and may be missed.

Urine sample collected over 24 hours.


Do not collect sample if you have a urinary tract infection until after completing any treatment.

48 hours prior to collecting your sample, avoid eating whole or ground flax seeds and sesame seeds.

24 hours before taking the sample, avoid over dilution of sample by limiting overall fluid intake of 1/2 oz water/fluid per pound of body weight per day. Example: 130 lbs -65 oz (eight 8 oz.glasses).


Please return via a next day service Monday – Thursday only. The sample must be stored in the fridge prior to returning and returned within 48 hours of collection.

A courier option is sent with your test kit. You pay the laboratory directly for this test and also the return courier if you use the service. You can also make your own arrangements for returning your samples via a next day service.

14 working days.

Your test results will be emailed to you.

Thyroid T3/T4