Which iodine test is the best?

With iodine present in every organ in the body, not only the thyroid gland, the benefits of having adequate levels of iodine are clearly important for a healthy functioning body.

The iodine loading test is an accurate way to measure your iodine levels. 

Establishing the correct level of iodine in your system is especially important due to the side effects of both over and undersupply of iodine. Iodine levels can be effectively identified through urine or saliva testing and once known, decisions can be made regarding supplementation.

If you have four or more of the symptoms listed below you should consider testing to establish your iodine level.

Symptoms of iodine deficiency which may be noted are:

iodine patch test validity
  • Unexplained weight gain
  • Feeling weak and fatigued
  • Dizziness
  • Sore or stiff joints in the morning
  • Difficulty learning and remembering
  • Suffer from brain fog – not as mentally alert as you should be
  • Headaches
  • Minor ringing in your ears
  • Menstrual difficulties
  • Loss of hair
  • Outer third of eyebrows are missing
  • Dry, cracked skin
  • Experiencing difficulties becoming pregnant
  • Subclinical depression
  • Low libido
  • Need more sleep than expected
  • Difficulty getting up in the morning
  • Have the “I can’t be bothered” feeling
  • Slow growing and brittle hair
  • Become constipated
  • Sensitivity to cold

If you are over 60 years of age, symptoms of iodine deficiency can be confused with those of ageing and may go undiagnosed.


What tests are used to measure iodine levels?

Testing Method 1: The iodine patch test is a general, and not a very scientific test, which can be completed at home. While it isn’t accurate it can give a general idea if you are deficient and if you need to seek further and more accurate testing. While you might start with this iodine test on the skin, ultimately the iodine loading test will provide more specific information.

What to do

Paint a patch, about 2 inches by 2 inches, of iodine tincture (orange) on the inner forearm or thigh. Allow to dry. Be aware that the tincture stains clothing. Now, wait to see what happens over the next 24 hours.

What does it tell you?

  • If you are iodine deficient the iodine will soak quickly into the body the and the patch will disappear before the 12-14 hours
  • If you are severely deficient the patch will disappear in less than 12 hours
  • If the patch doesn’t begin to fade until after 24 hours you are not iodine deficient

The timings are generalizations and used to establish your body’s overall need for iodine. To ascertain more precise dosage levels, you would be advised to seek more accurate testing measures.


Testing Method 2: Iodine Loading Test is obtained through a testing laboratory and shows iodine level in the body and the percentage eliminated through the urine over 24 hours. It incurs a cost and takes time, but it is accurate. This test detects mild through to severe deficiencies. This test was invented by Dr Brownstein, who is the author of Iodine: Why You Need It and is a recognized leader in this field.

What to do

  • This iodine deficiency test procedure requires an initial urine sample, taken first thing in the morning, to establish your baseline reading
    iodine deficiency urine test
  • Following this, you take a 50mg iodine tablet
  • Then you collect every sample of urine in the next 24 hours.

What does it tell you?

  • Someone who has sufficient iodine should expel about 90% of the iodine load over a 24-hour period.
  • If the person has insufficient iodine, the body will keep the iodine and small quantities will be excreted thus giving a low % reading.
  • The lower the elimination rate, the greater the iodine deficiency.


Testing Method 3: One sample urine test. This urine test is unreliable as it measures the iodine uptake from food and supplementation which varies greatly each day (1) and doesn’t provide information on the iodine saturation level. This test isn’t as accurate as the iodine loading test.

What to do

  • the urine sample is taken first thing in the morning and then sent to the lab

What does it tell you?

  • reports can include levels and urinary iodine and creatinine
  • the report shows your levels as being severe, moderate, mild iodine deficiency disorder or not as having a deficiency.


iodine deficiency treatmentIodine Testing Method 4: Serum/saliva ratio test shows the degree of use of iodine in the cell. Your health care professional will request these tests.

What to do

  • samples are collected from a collection centre and sent to a pathology lab.

What does it tell you?

  • A ratio below normal indicates a symporter defect(NIS) (2), however, if a ratio higher than normal is indicated then an organification problem is indicated (3).
  • It also indicates the levels of other halogens (fluoride, chloride and bromine). If the iodine uptake is low these halogens are probably high because they block the absorption of iodine.


Testing Method 5: A blood test is usually requested when regular tests indicate abnormalities in thyroid function, to see if abnormal iodine levels are causing the problem. It is also used if there are symptoms of iodine poisoning such as abdominal pain, vomiting, fever, low pulse, or burning of the mouth, throat, or stomach.

What to do

  • samples are collected at a collection centre and sent to a pathology lab.

What does it tell you?

  • A THS test measures the amount of T4 (thyroxine) the thyroid gland is signalled to make. If this level is high it may mean you have hypothyroidism (underactive thyroid)
  • A free T4 test and free T4 index combine with the THS test indicate how the thyroid is functioning
  • The presence of anti-TPO (anti-thyroid peroxidase) antibodies may indicate an autoimmune thyroid disorder, which is a factor in developing hypothyroidism.


Test for underlying causes of iodine deficiency

Tests which can identify the underlying causes and are worth considering as it is better to treat the underlying causes than just treating the symptoms with medication. In order to identify the causes, your healthcare practitioner may suggest the following: Adrenal Stress Test, Hair Mineral Analysis, Male or Female Hormone Panel.

Ignoring causes of iodine deficiency can lead to further health complications as well as developing symptoms from the medications. Therefore, considering the causes and evaluating your choices provides you with more options than just taking medication for the rest of your life.

Your test results aren’t normal? So, what are your options?

  • Research iodine deficiency information to find out how to prevent iodine deficiency
  • Work with your health care professional to identify and remove the causes
  • Seek out the supplements that work
  • Include iodine rich foods in your diet