Low iron does not directly cause cysts to form, but the two conditions are connected in ways that matter. Iron deficiency can disrupt ovarian function, stall normal follicle development, and weaken immune defenses in skin tissue. More often, though, the relationship runs in the opposite direction: cysts (especially ovarian ones) cause heavy bleeding that drains your iron stores. Understanding which way the arrow points in your situation is key to getting the right treatment.
How Iron Affects Ovarian Follicle Growth
Your ovaries need iron to develop eggs properly. Follicle growth is a period of rapid cell division and hormone production, and both of those processes demand large amounts of cellular energy. In animal research, iron-deficient mice had roughly one-quarter the ovarian energy levels of mice fed a normal diet (2.2 versus 9.3 units per gram of ovarian tissue). That energy shortfall caused follicle development to stall at an early stage. The follicles never matured to the point of ovulation, the normal hormonal cycle flatlined, and none of the iron-deficient mice became pregnant.
When a follicle starts to grow but can’t finish maturing, it sometimes persists as a fluid-filled sac on the ovary. This is the most common type of ovarian cyst, called a functional cyst. So while low iron doesn’t build a cyst the way a tumor grows, it can set the stage for one by disrupting the ovulation process that would normally prevent a follicle from lingering. The iron-deficient mice also showed significantly reduced estrogen production and lower activity of the receptor that responds to follicle-stimulating hormone, both of which are essential for a follicle to reach the ovulation finish line.
PCOS: Iron Is Typically High, Not Low
If you’re thinking about polycystic ovary syndrome, the iron picture is actually the reverse of what most people expect. Women with PCOS tend to have elevated iron and ferritin levels, not low ones. In a study comparing 45 women with PCOS to 45 controls, the PCOS group had ferritin levels nearly four times higher (155 versus 42 micrograms per liter) and serum iron more than double the control group.
This iron excess appears to be part of the metabolic dysfunction that characterizes PCOS. Obesity and insulin resistance, both common in PCOS, drive iron accumulation in tissue. That excess iron generates oxidative stress in the ovaries, which can impair how ovarian tissue functions. So for PCOS specifically, the concern is too much iron rather than too little. Interestingly, higher ferritin levels in these patients correlated with smaller ovary size, suggesting the iron overload itself may be reshaping ovarian tissue.
Cysts Often Cause Low Iron, Not the Other Way Around
The more common clinical scenario is that cysts lead to iron deficiency rather than iron deficiency leading to cysts. Ovarian cysts can cause heavy or prolonged menstrual bleeding (menorrhagia), and that blood loss steadily depletes your iron reserves. In one published case, a woman with large ovarian cysts developed severe iron deficiency anemia, with hemoglobin dropping to 6.6 grams per deciliter (normal is roughly 12 to 16) and ferritin falling to just 4.0 nanograms per milliliter. Her doctors concluded the cysts had caused ovarian dysfunction and thickening of the uterine lining, which together drove the heavy bleeding responsible for her anemia.
Endometriosis follows a similar pattern. Endometriomas, sometimes called “chocolate cysts,” are a hallmark of the condition, and women with endometriosis face a higher risk of iron deficiency than the general population. Part of this comes from the chronic inflammation endometriosis causes, and part from the heavy periods that often accompany it. When researchers adjusted for heavy bleeding, the link between endometriosis and iron deficiency weakened by about 8%, confirming that blood loss is a significant driver.
This creates a frustrating cycle. A cyst disrupts your period, the heavy bleeding drains your iron, low iron impairs your ovarian function further, and the hormonal disruption may allow more cysts to persist. If you have both low iron and ovarian cysts, it’s worth figuring out which problem came first, because treating only the iron without addressing the cyst (or vice versa) may not break the cycle.
Thyroid Nodules and Iron Deficiency
Ovarian cysts aren’t the only type people ask about. Thyroid nodules, which can be cystic (fluid-filled), solid, or a mix of both, are also linked to iron status. Cleveland Clinic lists iron-deficiency anemia as a risk factor for developing thyroid nodules. The thyroid gland needs iron to produce its hormones, and when iron is scarce, the gland can enlarge or develop nodular growths as it struggles to keep up. Thyroid nodules may also be associated with low thyroid hormone levels, which makes sense given that iron-deficient individuals often have impaired thyroid function. If you’re dealing with both low iron and a thyroid nodule, correcting the iron deficiency is a reasonable early step.
Skin Cysts and Immune Function
For skin-related cysts like sebaceous cysts or recurrent boils, the connection runs through your immune system. Iron deficiency weakens your body’s ability to fight off infection. Clinical features of low iron include a predisposition to skin infections such as boils, impetigo, and candidiasis. When your immune defenses are compromised, a blocked gland or hair follicle is more likely to become infected and develop into an inflamed cyst. Iron also plays a direct role in wound healing and skin repair, so iron-deficient skin may be slower to resolve minor blockages before they escalate.
That said, iron’s relationship with inflammation in the skin is not straightforward. Both too little and too much iron in immune cells called macrophages can fuel excessive inflammation. In iron deficiency, elevated levels of the hormone hepcidin can trap iron inside macrophages, creating localized iron overload in tissue even when your overall iron is low. This can worsen inflammation and impair healing at the cellular level.
How to Know If Your Iron Is Actually Low
Ferritin is the most reliable single blood test for iron stores. The World Health Organization recommends using a ferritin level below 15 micrograms per liter to identify iron deficiency in otherwise healthy individuals. If you have any ongoing inflammation or infection, the threshold rises to 70 micrograms per liter for adults, because inflammation artificially inflates ferritin readings and can mask a true deficiency.
Common symptoms of iron deficiency overlap with symptoms that cysts can cause: fatigue, dizziness, feeling cold, and sometimes pelvic discomfort or bloating (which can come from either an ovarian cyst or the heavy periods that iron deficiency may worsen). If you’re experiencing both fatigue and changes in your menstrual cycle, a simple blood panel checking ferritin, serum iron, and hemoglobin can help sort out whether iron deficiency is part of the picture. Identifying the deficiency matters, because restoring iron levels supports normal follicle development, thyroid function, immune defense, and the energy production your reproductive system depends on.