From the Guidelines
Combined oral contraceptives can cause mildly elevated prolactin levels in some users, typically remaining below 50 ng/mL, which is generally not clinically significant. The estrogen component in COCs is primarily responsible for this elevation, as estrogen stimulates lactotroph cells in the pituitary gland to produce more prolactin 1. Common COCs contain ethinyl estradiol (usually 20-35 mcg) combined with various progestins such as levonorgestrel, norethindrone, or drospirenone. The prolactin elevation is dose-dependent, with higher estrogen doses potentially causing greater increases.
Some key points to consider:
- Most users will not experience symptoms from this mild elevation, though rarely some might notice breast tenderness or galactorrhea.
- If prolactin levels are being measured for diagnostic purposes, it's essential to note current COC use when interpreting results 1.
- This mild elevation is reversible and typically resolves within weeks after discontinuing the contraceptive.
- If significantly elevated prolactin levels (>100 ng/mL) are found in a COC user, other causes of hyperprolactinemia should be investigated, as the contraceptive alone is unlikely to cause such high levels.
In terms of the impact on morbidity, mortality, and quality of life, the mild elevation in prolactin levels caused by COCs is generally not a significant concern 1. However, it's crucial to consider individual patient factors and medical history when prescribing COCs. The benefits of COCs in preventing unintended pregnancy and reducing the risk of certain health conditions, such as ovarian and endometrial cancer, often outweigh the potential risks associated with mildly elevated prolactin levels 1.
From the Research
Combined Oral Contraceptives and Prolactin Levels
- The use of combined oral contraceptives has been associated with a mildly elevated prolactin level in some studies 2, 3.
- A study published in 1985 found that the incidence of hyperprolactinemia in oral contraceptive users was higher than in control subjects (12% vs 5%) 2.
- Another study published in 1986 found that oral contraceptives containing less than 50 micrograms of estrogen had a small but significant stimulatory effect on prolactin secretion in normal women, with mean prolactin concentrations increasing from 8.9 ng/ml to 10.9 ng/ml over 12 months 3.
- A 2015 study found that oral contraceptive pills containing ethinyl estradiol and levonorgestrel slightly increased serum prolactin and macroprolactin levels in women with macroprolactinemia, with the effect correlating with baseline values 4.
Mechanism and Variability
- The exact mechanism by which combined oral contraceptives affect prolactin levels is not fully understood, but it is thought to be related to the estrogen component 2, 3.
- The effect of oral contraceptives on prolactin levels can vary between individuals, with some women experiencing a greater increase in prolactin levels than others 2, 3.
- The type and dose of estrogen and progestin in the oral contraceptive may also influence the effect on prolactin levels 5.
Clinical Implications
- The mildly elevated prolactin levels associated with combined oral contraceptives are generally not considered to be a significant clinical concern 2, 3.
- However, women with a history of hyperprolactinemia or other endocrine disorders should be monitored closely when using combined oral contraceptives 6.