endo-hirsutism-low-dose-oc-vte-risk

name	endo-hirsutism-low-dose-oc-vte-risk
description	This skill guides selection of a low‑dose estrogen oral contraceptive combined with a low‑risk progestin for premenopausal women with hirsutism who are at increased venous thromboembolism risk (e.g., obesity or age >39 years). It triggers when a patient presents with patient‑important hirsutism requiring pharmacologic therapy and has VTE risk factors without estrogen contraindications.

Select low‑dose estrogen OC with low‑risk progestin for women at higher VTE risk

STEP 1 — Gather Information

• Confirm diagnosis of patient‑important hirsutism (Ferriman–Gallwey score ≥8) despite cosmetic measures.
• Assess VTE risk factors: obesity (BMI ≥30), age >39 years, personal/family history of VTE, known thrombophilia, recent immobilization, smoking >15 cigarettes/day if >35 years.
• Screen for estrogen contraindications: active or history of VTE, thrombophilic mutation, uncontrolled hypertension (≥160/100 mmHg), migraine with aura, liver disease, breast cancer, pregnancy or breastfeeding.
• Determine desire for contraception and fertility intentions.
• Review current medications for drug‑interactions (e.g., anticonvulsants, antibiotics). Action: Proceed to risk stratification if hirsutism requires pharmacologic therapy, VTE risk factors present, and no estrogen contraindications.

STEP 2 — Rule In / Rule Out

• Rule in: Patient‑important hirsutism indicating need for pharmacologic therapy AND presence of at least one VTE risk factor (obesity or age >39) AND absence of absolute estrogen contraindications.
• Rule out: Any absolute contraindication to combined OC (prior VTE/thrombophilia, migraine with aura, uncontrolled hypertension, smoking >35 years, pregnancy, liver tumor, breast cancer) OR patient seeks fertility (OC not appropriate) OR no VTE risk factors (standard OC selection applies). Action: If ruled in, move to classification; if ruled out, consider alternative therapy (antiandrogen, lifestyle, or standard OC) per guideline.

STEP 3 — Classify or Stratify

• Use Table 2 to identify low‑risk progestins (lowest relative VTE risk). Preferred options:

  Progestin (generation)	Relative VTE risk	Absolute risk (per 10 000 women‑years)	Typical EE dose (mcg)
  Levonorgestrel (G2)	2.4	6	20‑30
  Norethindrone (G1)	2.6	7	20,35
  Norgestimate (G2‑3)	2.5	6	35

• Select an OC containing EE 20 mcg (lowest effective dose) plus one of the above progestins. Action: Prescribe the chosen low‑dose OC; document choice and counsel on VTE warning signs.

STEP 4 — Decide

• Initiate OC therapy with EE 20 mcg + selected low‑risk progestin.
• Schedule follow‑up at 3 months to assess hirsutism improvement and adverse symptoms.
• If hirsutism remains suboptimal after 6 months of monotherapy, add an antiandrogen (e.g., spironolactone 100‑200 mg/day) per guideline 3.5.
• Reinforce VTE education: advise immediate evaluation for leg swelling, pain, dyspnea, chest pain. Action: Continue OC and reassess per timeline; escalate therapy if needed.

Clinical Guardrails / Mimics / Pitfalls

• Do not use OC with higher‑risk progestins (desogestrel, gestodene, drospirenone, CPA) in women with VTE risk factors.
• Avoid OC in smokers >35 years or with migraine with aura due to synergistic VTE risk.
• Do not rely solely on OC for hirsutism if patient desires pregnancy; consider alternative (antiandrogen with reliable contraception).
• Monitor for subtle VTE signs; obesity and age >39 independently increase risk, so vigilance is essential.
• Do not exceed 6‑month monotherapy trial before considering antiandrogen addition.
• Beware of drug interactions that reduce OC efficacy (e.g., rifampin, certain antiepileptics).

Concrete Clinical Example

A 34‑year‑old woman with BMI 32, Ferriman–Gallwey score 14, reports patient‑important hirsutism despite shaving, desires contraception, denies prior VTE, migraine, or hypertension. She has obesity (VTE risk factor) and no estrogen contraindications. Following the algorithm, she is prescribed an OC containing EE 20 mcg + levonorgestrel 0.15 mg. At 3‑month visit, mild hirsutism improvement noted; at 6 months, response suboptimal, so spironolactone 100 mg/day is added. She continues OC with routine VTE vigilance.

Source: Endocrine Society Clinical Practice Guideline: Evaluation and Treatment of Hirsutism in Premenopausal Women, Martin et al., 2018, doi:10.1210/jc.2018-00241

TODO: consider adding scripts/calc.py for the endo-hirsutism-low-dose-oc-vte-risk calculator