The fourth thyroid indicator
The pairing that sits behind two minerals people usually read alone
Iron and copper are each interesting on their own. Set against each other they become one of the four indicators used to read thyroid activity.
On the Trace Elements governing set the iron to copper ratio has an ideal of 0.9 and an acceptable range of 0.2 to 1.6.
This is one where the number has moved. The 1993 figure was 1.12; the current governing figure is 0.9. An older report or an older article may quote the earlier one, so the year attached to a figure matters here more than on most ratios.
Analytical Research Labs does not publish a paired ideal for Fe/Cu, so unlike Ca/K or Na/K there is no two-lab range to give — the Trace Elements figure stands alone, and should be named as theirs.
Thyroid activity is read from four indicators rather than one, and Fe/Cu is the fourth:
Read alongside the sodium and potassium pairing and the rest of the set, it is a supporting indicator rather than a standalone verdict — which is exactly how the gland readings are constructed.
In the pattern system Eileen works from, Fe/Cu also appears in a combined reading. A double low ratio on the second four minerals is an iron/copper ratio below 0.7 together with a manganese/zinc ratio below 0.0015.
That combination is associated with past trauma and is described as a deeper pattern than the equivalent on the first four minerals. It often coincides with other indicators of the same kind, including a calcium shell or a four lows pattern.
Worth noticing: the ratio carries a different meaning inside that combination than it does on its own. Context changes what a number is saying.
The interpretive system attaches an infection trend to an iron/copper imbalance, and the reasoning given is specific enough to follow:
Two minerals, opposite effects on the same trend — which is again why the pair is read as a ratio rather than as two separate lines.
The same trend is associated with an oxidation rate pushed far in either direction, fast or slow, on the reasoning that an extreme rate leaves less adaptive energy available. The more skewed the rate, the stronger the reading.
Said properly: this is a trend the mineral pattern points toward, written the way the laboratories write it on the report. It is not a diagnosis, it does not mean an infection is present, and a screening test cannot establish one.
Fe/Cu is a ratio on a screening test. It does not diagnose a thyroid condition, it does not replace thyroid bloodwork, and it is read as one of four indicators rather than alone.
Its value is that it is a proportion held across two to three months of growth — a different kind of information from a single blood draw, answering a different question. Anything medical belongs with your own licensed provider.
Iron and copper are the two minerals people arrive with the strongest opinions about, usually formed from a single supplement decision. The ratio is more useful than either opinion.
I also check which figure a previous report was read against. The ideal moved from 1.12 to 0.9, and comparing a new result to an old interpretation is a quiet way to reach the wrong conclusion.
On the Trace Elements set, 0.9, with an acceptable range of 0.2 to 1.6. The 1993 figure was 1.12, so the year attached to any quoted ideal matters.
Analytical Research Labs does not publish a paired ideal for Fe/Cu, so unlike Ca/K or Na/K there is no two-lab range here. The Trace Elements figure should be named as theirs.
It is one of four indicators used to read thyroid activity in the laboratory system, alongside Ca/K, Ca/P and Na/Mg. It is a pattern reading on a screening test, not a diagnosis, and it does not replace bloodwork.
A full report gives Fe/Cu alongside the other thyroid indicators, so the four can be read as the set they were designed to be.
Published 2026-08-30 · Updated 2026-08-30
By Eileen Durfee — Practitioner, NBS (Nutritional Balancing Science), NASM-CPT; wellness educator, inventor and author.
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease. Hair tissue mineral analysis is a screening test and is not diagnostic; anything medical belongs with your own licensed provider. Wellness Shopping Online is operated by Nuco Enterprise Solutions LLC.
