Effect of Lasix (Furosemide) on Prolactin Levels
Based on the available evidence, Lasix (furosemide) does not increase prolactin levels and may actually be associated with a decrease in prolactin levels in certain clinical scenarios.
Relationship Between Furosemide and Prolactin
Direct Evidence
- A study specifically examining furosemide's effect on serum prolactin levels in the postpartum period found that while furosemide effectively inhibited lactation, it had no effect on raising serum prolactin levels 1.
- This suggests that furosemide's effects on lactation must be mediated by mechanisms other than altering prolactin secretion.
Contradictory Evidence
- A 1986 study in hypertensive patients showed that following acute furosemide administration, there was a fall in prolactin levels in patients who were initially hyperprolactinemic 2.
- However, the same study noted that after chronic furosemide treatment, there was a tendency toward prolactin rise in all patients 2.
Mechanism of Action and Clinical Implications
Physiological Pathway
- Furosemide primarily acts as a loop diuretic by inhibiting the sodium-potassium-chloride cotransporter in the ascending loop of Henle.
- Unlike medications known to cause hyperprolactinemia (such as antipsychotics, some antidepressants, and prokinetics) 3, furosemide does not directly affect dopamine pathways in the tuberoinfundibular system that regulate prolactin secretion.
Clinical Applications
- Furosemide has historically been used in combination with breast binding and fluid restriction to inhibit postpartum lactation 4, but this effect appears to be independent of prolactin levels 1.
- In patients with hypertension and hyperprolactinemia, the acute administration of furosemide may actually help lower prolactin levels 2.
Monitoring Considerations
When to Check Prolactin Levels
- Prolactin levels should be checked when clinically indicated based on symptoms such as galactorrhea, amenorrhea, or infertility.
- There is no evidence supporting routine monitoring of prolactin levels in patients taking furosemide.
Reference Ranges for Serum Prolactin
- Non-pregnant females: 3.0-30.0 ng/mL
- Pregnant females: 10.0-209.0 ng/mL
- Postmenopausal females: 2.0-20.0 ng/mL 5
Important Caveats
- The relationship between diuretics and hormone levels can be complex and may involve indirect mechanisms.
- Some studies suggest that dopaminergic mechanisms modulate various hormones including aldosterone, and bromocriptine (a dopamine agonist) can affect responses to furosemide administration 6.
- Most of the research on furosemide and prolactin is relatively old (1970s-1980s) and limited in scope.
In conclusion, healthcare providers should be aware that furosemide is not typically associated with increased prolactin levels and should look for other causes when hyperprolactinemia is present in patients taking this medication.