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Open WellbeingWhat the studies actually measured

Hormones, thyroid and fertility

Iodineand Thyroid-stimulating hormone (TSH)

Both sources here found no clear difference in thyroid-stimulating hormone (TSH).

How sure anyone can be

Low certainty, level 2 of 4

Further research is likely to change this.

The most certain of the two findings here; each record carries its own.

The numbers reported

One source’s range, drawn against its own line of no difference and scaled to its own numbers.

0.110.58 risk ratio3.12

This range crosses the no-difference line, so these numbers fit a real difference and no difference at all equally well.

Bar the confidence interval — the range the true effect is likely to sit inNotch the number the source reportedLine where there would be no difference at all

Two sources, newest first

What we read is the published abstract, not the full paper, so a blank below may still be printed in the paper itself. A fixed rule worked this out from the source’s own fields. Nobody checked this rating by hand.

  • Systematic review, 2017 · 2 studies pooled · 260 participants

    Very low certainty, level 1 of 4

    Iodine supplementation for women during the preconception, pregnancy and postpartum period.

    Cochrane Database Syst Rev. 2017;3(3):CD011761. doi:10.1002/14651858.CD011761.pub2. PMID:28260263.

    This source later carried a notice: Update of doi: 10.1002/14651858.CD011761. The number below is exactly as the source gave it.

    Number reported
    0.58 risk ratio
    Which way it went
    No clear difference
    Likely range
    0.11 to 3.12
    Source’s own words
    average risk ratio for neonatal hypothyroidism/elevated TSH
    Who was studied
    Pregnant
    Compared with
    placebo or no supplement
    Amount taken
    Not in the abstract
    For how long
    Not in the abstract
    Disagreement between studies
    Not in the abstract
    Kind of record
    Journal article
    How this rating was reachedstarts at High, 3 steps down: risk of bias, indirectness and imprecision
    1. Starts at High
    2. Risk of bias brought it down to Moderatethe abstract's own appraisal reports serious study limitationsReported in the abstract
    3. Indirectness brought it down to Lowthe outcome measured is a proxy for the target outcomeReported in the abstract
    4. Imprecision brought it down to Very lowthe confidence interval includes no effectReported in the abstract
    5. Ends at Very low3 steps down.
    Inconsistency
    No high disagreement reported between the 2 studies it pooled

    Imprecision stops at the first check that applies; others may apply too.

    AI-reviewed & signed — an AI agent re-read this finding against the saved source and checked that the quote, the numbers, the units and the direction match it. No person read it. The owner authorised the agent to sign the batch with the owner's key, and every build rechecks that signature against these exact bytes.

    Read the abstract on PubMed

  • Randomised trial, 2016 · 112 participants

    Low certainty, level 2 of 4

    Iodine Supplementation of Mildly Iodine-Deficient Adults Lowers Thyroglobulin: A Randomized Controlled Trial.

    J Clin Endocrinol Metab. 2016;101(4):1737-44. doi:10.1210/jc.2015-3591. PMID:26891118.

    Number reported
    Not in the abstract
    Which way it went
    No clear difference
    Likely range
    Not in the abstract
    Source’s own words
    Not in the abstract
    Who was studied
    Adult
    Compared with
    placebo
    Amount taken
    150 µg/d
    For how long
    168 days
    Disagreement between studies
    Not in the abstract
    Kind of record
    Journal article
    How this rating was reachedstarts at High, 2 steps down: risk of bias and imprecision
    1. Starts at High
    2. Risk of bias brought it down to Moderatethe abstract reports no risk-of-bias or quality appraisal, so study limitations cannot be ruled outNot in the abstract
    3. Imprecision brought it down to Lowthe abstract reports no confidence interval for the estimateNot in the abstract
    4. Ends at Low2 steps down.
    Checked, nothing to step it down for
    indirectness
    Inconsistency
    One study, so there was nothing to disagree

    Imprecision stops at the first check that applies; others may apply too.

    AI-reviewed & signed — an AI agent re-read this finding against the saved source and checked that the quote, the numbers, the units and the direction match it. No person read it. The owner authorised the agent to sign the batch with the owner's key, and every build rechecks that signature against these exact bytes.

    Read the abstract on PubMed

What is still missing from these readings

  • One give no number at all, only which way it went.
  • One gives no likely range, so how precise that number is is unknown.
  • Amount taken — One of Two readings: Not in the abstract.
  • For how long — One of Two readings: Not in the abstract.

Something nobody wrote down is never a zero and never a guess.

Still to read for Iodine

One of the six things on our list for Iodine has no reading here yet:

  • Iodine, Serum

Still to read means nobody here has got to it, not that it was tried and did nothing or that no research exists. A pairing on no list is not a gap: we never set out to read it.

Read next

This is a library, not advice. No recommendation, no dose, no diagnosis, no ranking. We never ask about your symptoms, and nothing here is tailored to you.