What is the recommended progestin and dosing regimen for a patient starting Hormone Replacement Therapy (HRT) with an estrogen patch?

Recommended Progestin for HRT with Estrogen Patch

For a patient starting HRT with an estrogen patch, micronized progesterone (100-200 mg daily for 12-14 days of each month) is the recommended progestin due to its physiological and safe profile. 1, 2

Progestin Options and Dosing

When using estrogen therapy in a patient with an intact uterus, a progestin must be added to prevent endometrial hyperplasia and cancer risk 1, 3. The recommended options include:

First-line choice:

• Micronized progesterone: 100-200 mg orally daily for 12-14 days every 28 days
  • SIG: "Take 1-2 capsules by mouth at bedtime for days 1-14 of each month"
  • Take at bedtime to minimize drowsiness (its main side effect)

Alternative options (if micronized progesterone is contraindicated or poorly tolerated):

• Medroxyprogesterone acetate (MPA): 5-10 mg daily for 12-14 days every 28 days
• Norethisterone: 5 mg daily for 12-14 days every 28 days

Timing of Progestin Initiation

Progestin therapy should be initiated:

• After at least 2 years of estrogen therapy OR
• When breakthrough bleeding occurs 1

This timing allows for proper endometrial development before adding progestin protection.

Administration Patterns

Two main administration patterns exist:

1. Sequential/Cyclic therapy: Progestin given for 12-14 days each month

   • Results in regular withdrawal bleeding
   • May be preferred for women who want monthly bleeding patterns

2. Continuous therapy: Lower daily doses of progestin without interruption

   • Can lead to amenorrhea after approximately 5 cycles 4
   • May be preferred for women who wish to avoid monthly bleeding

Clinical Considerations

• Safety profile: Micronized progesterone has fewer metabolic and vascular side effects compared to synthetic progestins like MPA 5
• Monitoring: Patients should be reevaluated every 3-6 months to determine if treatment is still necessary 1, 3
• Endometrial protection: Before starting progestin, a sonographic evaluation may be advised to demonstrate proper endometrial thickness 2

Potential Pitfalls and Caveats

• Inadequate progesterone therapy increases risk of endometrial hyperplasia 1
• Continuous progestin regimens may affect lipid profiles differently than sequential therapy, with potential increases in triglycerides and less favorable effects on LDL cholesterol 6
• Breakthrough bleeding is common in the first few months of therapy and should not necessarily prompt discontinuation
• Transdermal progestin options exist in some countries as combined patches with estradiol for either continuous or sequential administration 2

Remember that hormone therapy should be used at the lowest effective dose and for the shortest duration consistent with treatment goals and risks 1, 3.