Why I look for environmental factors in hormonal disorders

You are sitting there with a lab report on which everything is within range. Estradiol matching the cycle day. TSH unremarkable. Prolactin normal. The ultrasound was without findings, or with a finding that already has a name.

And still something is off. The cycle has become restless. Your skin reacts differently than it used to. The second half of the cycle feels like a different person. The exhaustion does not sit in your legs but behind your forehead.

Many women know this pattern. The work-up was correct and complete. It ruled out what had to be ruled out. It simply answers a different question from the one you came with. It answers: is there a disease here for which a treatment exists. Your question is: why is my system out of rhythm.

Those are two different questions. Both are legitimate. For the first there are guidelines, for the second there is a grid, a few good studies and many open spots. That is exactly what I am writing about here.

These labels sit next to every study from here on. In this field they are the single most important distinction. Leave them out and a rat study turns into a statement about your cycle. That happens constantly online, and it is the reason this topic has a poor reputation.

When the work-up is sound and the question remains

Picture two kinds of consultation. In one, the point is to confirm or rule out a diagnosis. That is precise work with clear rules. In the other, the point is to understand a course of events. That is blurrier, slower and needs more time than a standard appointment usually has.

The gynaecological work-up delivers the first, and it delivers it well. It clarifies whether PCOS lies behind your symptoms, or endometriosis, a thyroid disease, a prolactinoma, an early perimenopause. These distinctions are not incidental. They decide about treatments that can genuinely change something.

That is why the order in this article is not negotiable: the gynaecological work-up remains the foundation. The environmental perspective comes on top and never in its place.

Let us stay with the second kind of consultation. Often someone sits there with a diagnosis that explains only half of the symptoms. PCOS explains the irregular cycle, not the headaches. Endometriosis explains the pain, not the exhaustion since the move.

At this point a sentence regularly turns up that I do not like: they found nothing. It is not accurate. They searched very carefully for certain things and did not find them. That is something else.

The second sentence that often falls: maybe it is psychological. That one is too quick for me as well. Not because the mind plays no part. Rather because it usually comes at the end of a list that has been worked through.

I want to be clear here about why routine care stops at this border. It is not disinterest. A guideline may only recommend what studies support with a tested consequence. Meaning: if we measure this and act on it, people are measurably better off. For environmental diagnostics in hormonal complaints exactly that kind of study is missing. The mechanisms are not missing. The intervention studies are.

That is not an omission. That is the method by which guidelines are built, and it has a good reason. It protects people from investigations whose benefit nobody has shown. Added to this are training priorities and time budgets: environmental toxicology is not at the centre of gynaecological training, and a detailed exposure history takes more time than a routine appointment usually allows.

What I do differently is therefore not better. It is a different frame. In my private practice I have more time for the history, I ask routinely about housing, occupation and exposures, and I work with probabilities rather than exclusions. Many colleagues would do the same if the frame allowed it. That comes at a price: I move more often in the territory of assumption. Which is why this text states at every point how certain something is.

And now you know why I keep asking when the work-up was clean.

Hormones are a signalling system, and signalling systems have four weak points

Think of a radio message. For a message to arrive, four things are needed. A transmitter that sends it. A transmission path along which it travels. A receiver that can pick it up at all. And someone who clears the old message from the buffer so the new one has room.

If one of these four fails, the message does not arrive properly. But the fault looks different each time. And, this is the point: if you only measure how loudly the transmitter is sending, you miss three faults out of four.

Now the question becomes concrete. An estradiol value in the blood measures level one, meaning what is circulating right now. It says little about how much of it is freely available, whether the receptor is currently responding well and whether breakdown is keeping up.

For the second level there is a lab value you have probably seen on a report before: SHBG. That is the transport protein for sex hormones. It is the bus they travel in, and it co-determines how many get off at the stop.

On to the third level, the receptor. Something happens here that the image of key and lock explains well. A hormone made by the body is the matching key. A foreign substance can be a key that also fits the lock but turns it only halfway. Or one that gets stuck in the lock.

The Endocrine Society has compiled these pathways in two detailed statements, in 2009 and 2015. Named are estrogen-like and antiandrogenic effects, interference with thyroid pathways, with the fat metabolism switch PPAR-gamma, with retinoid pathways, with steroidogenic enzymes and with neurotransmitter systems. This is not a fringe position. It is the position of a large endocrinological professional society.

On to the fourth level, breakdown. Estrogens are rebuilt in the liver in two steps and then moved out via bile and gut. If that route is sluggish, more stays in circulation than the transmitter ordered. That is a chapter of its own, which I am not opening here. If you want it in more detail, it is under lowering estrogen naturally via the liver.

That also explains why symptoms in this field are rarely of a single type. When a control centre becomes quieter, that affects more than the cycle. It also helps steer thyroid, stress axis and appetite. Which is why in these cases someone so often sits there whose cycle, sleep, skin and digestion are all restless at once.

One final point on level one, so that no wrong impression arises. There are good reasons to take hormone measurement seriously, and there are rules about when which value is informative at all. Measuring progesterone on cycle day three makes about as much sense as reading the August rain gauge for January. Which test shows something when is under hormone testing: which test when.

And now you know why I keep asking after the lab report rather than stopping.

Search direction one: endocrine disruptors from the environment

The most common objection comes quickly and it is legitimate: the amounts are tiny. A little plasticiser from a packaging cannot rearrange a menstrual cycle.

The argument holds in classical toxicology. There the rule is: more poison, more effect. With hormones this works differently, for a simple reason. Hormones themselves operate in tiny amounts. Estradiol sits in the range of picograms per millilitre. A system designed for signals that small does not respond by the rules of a poisoning.

Now to the human data. And here it gets interesting, because the honest numbers are smaller than the topic sounds online.

The next example is instructive because it shows how easily an arrow gets drawn in the wrong direction in this field.

The methodologically cleanest work in this chapter comes from a large cohort of women and concerns an endpoint that leaves nobody cold: the timing of menopause.

And then there is the historical observation that set this field in motion in the first place. It comes from an animal experiment and from the year 1993.

That leaves the question of how the agencies see it. And here lies the most honest news of this whole chapter: they see it differently.

What follows from this for everyday life? Very little drama and a few low-risk directions. Fewer hot foods in plastic, less receipt paper in the hand, ventilating after renovation, sparing use of fragrance. Physically these steps are low-risk, their benefit in an individual case cannot be proven, and they carry one side effect that is rarely discussed: they can lead into a spiral of avoidance. How I handle that is further down, in the paragraph against compulsive control. The concrete list is under xenoestrogens in everyday life, there with the sources and without panic.

And now you know why I ask about packaging, occupation and renovations.

Search direction two: mould toxins and the mycoestrogen zearalenone

I ask this question almost always, and it almost always comes as a surprise: was there ever water damage where you live? A damp corner? A move after which something changed?

The reason for the question is a word with a firm place in toxicology: mycoestrogen. There really are mould toxins whose main action is estrogen-like. This is not a fringe opinion. It is written in a regulatory risk assessment.

How such a substance intervenes in the control centre is shown particularly vividly by a rat study. It explains the mechanism. And it works with doses far above anything found in a flat.

In humans there is exactly one usable observation, and I am showing it to you with all its limitations, because online it is readily made larger than it is.

And now comes the paragraph I consider the most honest of the whole article.

Added to this is a distinction that almost always blurs online. Zearalenone is a food mycotoxin. It comes via grain, not via the wall of a room. Household mould is a different topic with different substances and a different evidence base.

How large is the demonstrated effect of housing dampness in the first place? A meta-analysis gives a usable order of magnitude for calibrating expectations.

If you want to go deeper on mould: what mycotoxins are in the first place is under mycotoxins: the basics. Zearalenone in detail is under zearalenone as a mycoestrogen, and which symptoms fit a mould exposure at all is under mould symptoms at a glance. What to do about visible growth in the home is under mould in the home.

And now you know why I ask about the flat without turning it into a diagnosis.

Search direction three: heavy metals, above all cadmium and lead

Heavy metals are the topic most exaggerated online and least asked about in the consultation. I find both a shame, because in between there is a solid core.

The core is called metalloestrogen. Meant are metals that can dock at the estrogen receptor and set off a signal there. For cadmium this has been shown in the living animal, and the experimental design is elegant enough that I am happy to explain it to you.

In humans it looks different, thinner and blurrier. The best bridge that exists comes from a large population-representative survey in the USA.

And now the finding I consider indispensable, because it points the other way. Lead is generally regarded as the classic among fertility poisons. In one occupational medicine study, nothing of the sort was visible in the low exposure range.

Plausible sources are, for instance, smoking as the main source of cadmium, certain occupations, renovation of old buildings, drinking water pipes in very old houses. What blood and urine measurements each show and do not show is set out in detail under measuring heavy metals in blood or urine. Why I advise against hair mineral analysis for individual questions is under hair mineral analysis: useful or not.

And now you know why with metals I ask first about the source and then about the laboratory.

Search direction four: silent inflammation

This fourth direction is the least spectacular and in practice the most common. It has no name you can google, no flat you could renovate, and no substance you can avoid.

What is meant is a permanently slightly activated immune state. It arises not from an infection but from belly fat, from lack of sleep, from gut issues, from dental foci, from chronic stress, sometimes also from one of the other three search directions. And it has two points of attack on your hormone system, both well described.

The first point of attack is at the top, in the control centre. There is an animal model for this that takes the mechanism cleanly apart.

In humans there is a prospective cohort on this with a clear number and a built-in modesty.

The second point of attack of inflammation is the one I use most often in everyday practice, because it appears on every larger lab report: SHBG. You remember level two, transport. Pro-inflammatory messengers may downregulate SHBG production in the liver, and liver fat content appears to matter more than BMI alone.

How blood sugar and insulin fit into this picture is under insulin resistance and hormones in women. Why chronic stress is almost always part of it is under cortisol, stress and female hormones.

And now you know why I ask about sleep, gut and dental status before I talk about plasticisers.

When this search is worthwhile and when it explicitly is not

This is the section that decides whether this article is worth anything. Everything so far was mechanism and evidence. Now comes the question you actually have: does this concern me?

I will start with the sentence that stands above everything. From the fact that environmental factors can act hormonally it does not follow that every hormonal disorder has an environmental cause. The most common reasons for hormonal complaints are and remain sleep, stress, blood sugar, weight, thyroid and nutrients.

That is not a modesty formula. It is written, in other words, in an Endocrine Society guideline on functional hypothalamic amenorrhoea: chronic anovulation without a tangible organic cause, often linked to stress, weight loss, a very high exercise load or a combination of these. Explicitly a diagnosis of exclusion, and the work-up is meant to cover systemic and endocrinological causes.

On the fourth point on the right I will be blunt, because it is the most important. Time is a real factor in some situations. When trying to conceive. With endometriosis involving organs. With unexplained bleeding. Anyone who puts an environmental search first in such situations gains no insight but loses months. Cause-finding runs alongside medical care, never in its place and never before it.

Why that matters so much is shown by a look at the guidelines themselves. The international PCOS guideline of 2023 comprises 254 recommendations and practice points, GRADE-based, carried by 39 organisations from 71 countries. Environmental factors, mould or heavy metals do not appear there in the recommended basic work-up. The ESHRE guideline on endometriosis of 2022 with 109 recommendations states explicitly that for most treatment options no firm recommendations could be formulated on the basis of the available evidence. In Germany the S2k guideline on endometriosis is added to this, AWMF registry number 015-045, current version from 2025.

In my practice this means: I ask the question when the cluster speaks for it. I do not ask it first. And I treat it as a question and not as an explanation, as long as I have only an association and no cause. That is clinical observation and approach, not a study result.

And now you know when this search contributes something and when it gets in the way.

What tests can do and what they explicitly cannot

When people discover this topic, the first impulse is almost always the same: then just let me test for it. I understand the impulse well. And I have to dampen it, because in this field it rarely leads to an answer.

The principle first, and it holds without exception: no available test proves a cause. At best it shows an exposure. From exposure to an explanation of your symptoms is a long way, and no lab value covers that way on its own.

With the mycotoxin urine test the problem lies elsewhere. It does measure something. It is just that a positive finding is so common that on its own it says little.

With inflammatory markers there is an additional peculiarity that is often overlooked in everyday practice: a CRP value without the cycle phase noted is hard to place, because it fluctuates with the cycle itself. Anyone measuring should note which cycle day it was.

And on hormone measurement itself: it is sensible when timing and question match. Which value shows what and when is set out in detail under hormone testing: which test when.

The paragraph against compulsive control

Now comes something that matters more to me than all the numbers before it. Environmental topics have a property that can make them risky: they are never finished.

There is always another packaging you could replace. Another piece of furniture that might off-gas. Another test you could do. Anyone who starts checking everything will always find something. And the more you find, the more the fear grows instead of the clarity.

I see this regularly, and I describe it as an observation, not as a study result. Someone who starts with a good question sometimes eats only five foods half a year later and sleeps worse than before. Then the search has cost more than it brought.

Energy and a calm cycle are not a luxury. They are a large part of how free a life feels. Which is exactly why the search for them must not itself become a prison.

And now you know why I am sparing with testing and generous with listening.

Frequently asked questions

Where this article connects to the rest of the cluster

This text is the map. The individual countries on it have their own articles, because they have their own evidence and their own practical questions. Depending on where you currently stand, one of these routes leads onward.