What is the relationship between serum iron levels and testosterone levels in men?

From the Guidelines

Iron levels play a crucial role in maintaining healthy testosterone levels in men, and iron deficiency can lead to reduced testosterone production, which can cause symptoms like fatigue, decreased libido, and reduced muscle mass. The relationship between iron levels and testosterone levels in men is significant, with iron deficiency potentially leading to lower testosterone production [ 1 ]. Men with low iron levels may experience reduced testosterone, which can cause symptoms like fatigue, decreased libido, and reduced muscle mass. Conversely, excessive iron (hemochromatosis) can also negatively impact testosterone by damaging the testes.

Importance of Iron for Testosterone Production

For optimal testosterone production, men should maintain healthy iron levels through a balanced diet including iron-rich foods like red meat, spinach, and legumes. If iron deficiency is suspected, a healthcare provider can order blood tests to check ferritin, hemoglobin, and total iron binding capacity. Treatment for iron deficiency typically involves iron supplements (such as ferrous sulfate 325mg once or twice daily) for several months until levels normalize [ 1 ].

Biological Connection Between Iron and Testosterone

The biological connection exists because iron is essential for the enzymes involved in testosterone synthesis, particularly in the Leydig cells of the testes [ 1 ]. Additionally, iron is necessary for proper red blood cell function, which ensures adequate oxygen delivery to all tissues, including those responsible for hormone production.

Key Considerations

Some key considerations include:

• Maintaining healthy iron levels through a balanced diet
• Screening for iron deficiency in men with symptoms of low testosterone
• Using accurate and reliable assays to measure testosterone levels
• Considering the risks and benefits of testosterone replacement therapy in older men with hypogonadism [ 1 ].

From the Research

Relationship Between Iron Levels and Testosterone Levels in Men

• The relationship between iron levels and testosterone levels in men is complex, with some studies suggesting that testosterone replacement therapy (TRT) can improve iron levels and correct anemia in men with hypogonadism 2, 3.
• A study published in 2020 found that testosterone replacement significantly increased hemoglobin in men with unexplained anemia, and tended to increase hemoglobin in men with iron deficiency anemia, although the response was more variable and not statistically significant 2.
• Another study published in 2023 found that TRT was more efficacious than placebo in correcting anemia in middle-aged and older men with hypogonadism and anemia, and that a smaller proportion of testosterone-treated men developed anemia than placebo-treated men 3.
• Iron deficiency is a common condition that can cause symptoms such as fatigue, exercise intolerance, and difficulty concentrating, and can be diagnosed by low serum ferritin or transferrin saturation 4.
• The causes of iron deficiency should be identified and treated, and oral iron is typically first-line therapy, while intravenous iron is indicated for patients with oral iron intolerance, poor absorption, or certain chronic inflammatory conditions 4.

Mechanisms of Iron and Testosterone Interaction

• Testosterone replacement therapy has been shown to suppress hepcidin and ferritin in men with unexplained anemia, which can lead to increased iron mobilization and improved hemoglobin levels 2.
• The decrease in hepcidin was moderately correlated with the increase in hemoglobin in men with unexplained anemia, suggesting that hepcidin plays a role in the regulation of iron metabolism in response to testosterone replacement therapy 2.
• Testosterone has been shown to modulate sexual motivation and erection, and also plays a broader role in men's health, including the regulation of iron metabolism 5.

Clinical Implications

• The diagnosis of hypogonadism is often neglected, and the opportunity to replace low testosterone in older men is highly debated, highlighting the need for further research and individualized treatment approaches 6.
• Testosterone replacement therapy should be carefully assessed in older men, taking into account the potential benefits and risks, including the potential for improved iron levels and correction of anemia 5, 3.
• Iron deficiency and iron-deficiency anemia are common conditions that may cause symptoms such as fatigue, exercise intolerance, and difficulty concentrating, and should be diagnosed and treated promptly to improve quality of life 4.