Finasteride and Ferritin Levels
No, finasteride does not elevate ferritin levels; in fact, testosterone administration (which finasteride does not provide) actually reduces serum ferritin by approximately 32% within 3 months, and this effect occurs independently of finasteride's inhibition of 5-alpha-reductase. 1
Mechanism and Evidence
Finasteride reduces dihydrotestosterone (DHT) but does not alter iron metabolism or ferritin levels. The drug works by specifically inhibiting the 5-alpha-reductase enzyme that converts testosterone to DHT, without possessing any androgenic, antiandrogenic, or other steroid hormone-related properties. 2
Key Research Findings
A controlled study in older hypogonadal men demonstrated that testosterone-enanthate administration reduced serum ferritin by 32% (P = 0.002) within 3 months, while simultaneously suppressing serum hepcidin by 57% and increasing red blood cell production. 1
Critically, co-administration of finasteride (5 mg/day) did not significantly alter any of these testosterone-induced effects on iron homeostasis or ferritin levels. This demonstrates that finasteride itself has no direct impact on ferritin metabolism. 1
The testosterone-induced changes in iron homeostasis occurred independently of the type II 5-alpha-reductase enzyme, meaning that elevated DHT is not required for alterations in ferritin or iron incorporation into red blood cells. 1
Clinical Implications
If a patient on finasteride presents with elevated ferritin, look for alternative causes unrelated to the medication. Common causes of markedly elevated ferritin (>1000 μg/L) include: 3
- Malignancy (most frequent cause in one large series: 153/627 cases) 3
- Iron-overload syndromes (second most common: 136/627 cases) 3
- Inflammatory conditions (though less common than often assumed) 3
- Infection or chronic inflammation 3
Important Caveats
Finasteride has no binding affinity for androgen receptor sites and does not alter testosterone levels outside the normal range, though testosterone may increase slightly within normal limits. 4
The drug's pharmacological effects are highly specific to tissues containing high concentrations of 5-alpha-reductase (prostate, scalp, genital skin), making systemic effects on iron metabolism biologically implausible. 4
Finasteride's well-documented adverse effects are limited primarily to sexual dysfunction (decreased libido, impotence, decreased ejaculate volume in 2-4% more patients than placebo), with no reported effects on hematologic parameters or iron metabolism. 5, 6