Norethisterone (Norethindrone) in Menorrhagia - YES, It Can Be Used

Mechanism of Action

• Suppressing estrogen receptors in the endometrium
• Stabilizing and decidualizing the endometrial lining
• Reducing endometrial proliferation, which decreases blood loss
• At higher doses - causing endometrial atrophy

Indications in Menorrhagia

Dosing Regimens

• 5 mg three times daily, days 5-26 of the menstrual cycle
• Reduces blood loss and regulates cycle
• Less effective than LNG-IUS but widely used

• 5 mg three times daily (15 mg/day) until bleeding stops, then taper
• Some protocols use up to 15-30 mg/day for acute episodes
• Bleeding typically stops within 3 days

• 30 mg/day continuously - used pre-operatively or in severe cases

Comparison with Other Options for Menorrhagia

Limitations of Norethisterone in Menorrhagia

1. Short luteal-phase regimens (days 15-26) are NOT effective - this is a common mistake. The luteal-phase-only regimen does not adequately suppress the endometrium.
2. Androgenic side effects: acne, weight gain, mood changes
3. Does not provide contraception at standard doses
4. Oral bioavailability variability
5. Not suitable if endometrial cancer is suspected (needs histological exclusion first)

Current Guideline Preference

• LNG-IUS is the first-line for long-term menorrhagia management
• Tranexamic acid + NSAIDs are preferred non-hormonal options
• Progestogens (including norethisterone) are used when estrogen is contraindicated or when there is concern for endometrial hyperplasia/pathology
• Perimenopausal/older women - progestin-only (norethisterone or medroxyprogesterone acetate) is preferred over combined OCPs due to the risk of endometrial pathology

Key Clinical Points

• Always rule out endometrial pathology (TVUS/hysteroscopy/biopsy) before long-term progestogen use in women >40 years
• Norethisterone can be given and is effective, but newer options like LNG-IUS offer superior blood loss reduction
• For acute control in the ED, either combined OCP or progestin-only (norethisterone/medroxyprogesterone) stops bleeding within ~3 days
• Norethisterone is NOT recommended in the short luteal phase (days 15-25 only) - it requires longer coverage to be effective

Patient on Day 3 of Menses with Heavy Bleeding - Management

First: Can You Give Norethisterone NOW (Day 3)?

Step 1 - Assess Severity First

Step 2 - Acute Medical Management (Day 3, Active Bleed)

Option A: Tranexamic Acid (FIRST LINE - non-hormonal)

• 1 g (1000 mg) orally 3 times daily for up to 5 days
• Can be started on ANY day of bleeding - including day 3
• Antifibrinolytic - stabilizes clots at the endometrial surface
• Reduces blood loss by ~50%
• No hormonal side effects
• Also available IV (1g IV over 10 min) if severe or unable to take orally

Option B: NSAIDs (add-on or alternative)

• Mefenamic acid 500 mg TDS OR Ibuprofen 400 mg TDS OR Naproxen 500 mg BD
• Reduces PGE2 (vasodilator) and increases thromboxane A2 (vasoconstriction)
• Can be started on any day of active bleeding
• 20-50% reduction in blood loss
• Best combined with tranexamic acid

Option C: High-dose Norethisterone (hormonal acute control)

• 5 mg TDS (three times daily) - start immediately regardless of cycle day
• Continue until bleeding stops (usually 3-5 days), then taper
• After bleeding stops: switch to cyclical regimen days 5-26 of next cycle (5 mg TDS) to prevent recurrence
• Mechanism: rapidly stabilizes/decidualizes the proliferating endometrium
• Note: Median time to stop bleeding = ~3 days

Option D: Combined OCP (if no estrogen contraindication, younger patient)

• Monophasic pill containing 30-35 mcg EE
• 3 tablets/day for 7 days (acute control), then taper to 1 tablet/day
• Preferred in young women without estrogen contraindications
• NOT suitable for older/obese/perimenopausal patients (endometrial pathology risk)

Step 3 - If Haemodynamically Unstable (Severe)

• IV access + resuscitation with fluids
• IV conjugated estrogens 25 mg IV every 4-6 hours (fastest hormonal haemostasis) - stabilizes endometrial capillaries rapidly
• Blood transfusion if Hb < 7 g/dL or symptomatic anaemia
• Urgent gynaecology referral
• Consider IV tranexamic acid

Why NOT the Standard "Day 5-26" Norethisterone Regimen Here?

Summary Algorithm for Day 3 Heavy Bleeding

Day 3 Heavy Bleeding
        |
   Haemodynamically stable?
   /                       \
 YES                        NO
  |                          |
Start:                    Resuscitate
1. Tranexamic acid 1g TDS  IV estrogen 25 mg
2. + NSAID (mefenamic 500  IV tranexamic acid
   mg TDS)                 Blood transfusion
3. ± Norethisterone 5 mg   Urgent gynae referral
   TDS (if persistent or
   no response to above)
        |
  Plan cyclical norethisterone
  days 5-26 of NEXT cycle
  OR LNG-IUS at follow-up

Key Teaching Point

Tranexamic acid + NSAID are the safest and most immediately effective drugs to start on any day of active bleeding, including day 3. Norethisterone at acute high dose can be added or used alone, but the standard cyclical "day 5-26" regimen is for future cycle control - not for arresting a bleed already in progress.

Understanding "Day 5 to Day 26" of the Menstrual Cycle

The Menstrual Cycle - Day Count

Day 1 = First day of bleeding (menstruation starts)
Day 2 = Still bleeding
Day 3 = Still bleeding (your patient is HERE)
Day 4 = Bleeding slowing
Day 5 = Bleeding usually ending/ended
Day 6-13 = Proliferative phase (estrogen rising, endometrium rebuilding)
Day 14 = Ovulation
Day 15-28 = Luteal/secretory phase (progesterone dominant)
Day 28/29 = Next period starts → becomes Day 1 again

Why Start Norethisterone on Day 5?

• By day 5, the old endometrium has shed
• The new endometrial lining is just starting to grow (early proliferative phase)
• Starting norethisterone here prevents excessive proliferation of the endometrium throughout the cycle
• You give it all the way to day 26 (covering the entire proliferative + secretory phase)
• When you stop it on day 26, a controlled, lighter withdrawal bleed occurs

Day 1----Day 5----Day 14----Day 26----Day 28
 |          |        |          |        |
Bleed    Start     Ovul.     Stop    Period
starts   Noreth.   (supp.)   Noreth.  (light,
         5mg TDS             → with-  controlled)
                               drawal
                               bleed

The Key Concept

For Your Day-3 Patient Specifically

• She is still bleeding on day 3
• You cannot wait until day 5 to start the cyclical regimen - that would be for the NEXT cycle
• Right now, you give acute treatment: tranexamic acid, NSAIDs, ± high-dose norethisterone to stop the current bleed
• Then, once this period ends, you counsel her: "From day 5 of your NEXT period, start norethisterone 5 mg TDS and continue until day 26" - this controls future cycles

Simple Memory Trick

"Day 1 = Day bleeding STARTS. Day 5 = near end of bleeding. Day 5-26 norethisterone = cover the whole non-bleeding part of the cycle to keep endometrium thin."

Day 5 of the CURRENT Menses

For Your Patient (Currently on Day 3):

TODAY = Day 3 (heavy bleeding)
         ↓
    Day 4 (bleeding reduces)
         ↓
    Day 5 ← START Norethisterone 5mg TDS HERE
         ↓
    Continue daily until...
         ↓
    Day 26 → STOP
         ↓
    Day 28-30 → Withdrawal bleed (lighter, controlled)

So the Plan for This Patient is:

Important Points

1. You do NOT wait for the next cycle - day 5 of the current cycle is just 2 days away for her
2. She is on day 3 now → day 5 is just 2 more days
3. By day 5, her bleeding should be settling (also helped by tranexamic acid given now)
4. Starting on day 5 means she gets full cycle coverage (day 5 through day 26 = 21 days of norethisterone)

Why This Works

Without norethisterone:
Estrogen → endometrium grows thick → heavy bleed next month

With norethisterone day 5-26:
Progestogen → endometrium stays thin → light controlled bleed

Bottom line: Yes - start on Day 5 of the CURRENT cycle. For your patient on day 3, that means start norethisterone in just 2 days, after first controlling the acute bleed with tranexamic acid today.