Next Steps for Normal FSH and LH Levels in Infertility
For patients with normal FSH and LH levels experiencing infertility, a complete reproductive evaluation of both partners is essential, as normal gonadotropin levels indicate the need to investigate other potential causes of infertility.
Initial Assessment
Male Partner Evaluation
- Complete semen analysis is the cornerstone of male infertility evaluation 1
- Should be collected after 2-3 days of abstinence
- Normal parameters: volume 1.5-5.0 mL, pH >7.2, sperm concentration >20 million/mL
- Hormonal evaluation beyond FSH/LH 2, 1:
- Serum testosterone (to rule out hypogonadism with normal gonadotropins)
- Consider prolactin if low testosterone with low/normal LH
- Consider estradiol if gynecomastia present
Female Partner Evaluation
- Confirm ovulation through:
- Menstrual history
- Mid-luteal phase progesterone levels
- Transvaginal ultrasound for follicular monitoring
- Assess tubal patency via hysterosalpingogram or sonohysterography
- Evaluate uterine cavity with sonohysterography or hysteroscopy
Potential Diagnoses with Normal FSH/LH
For Women
- Functional hypothalamic amenorrhea with polycystic ovarian morphology 2
- Look for energy deficit, excessive exercise, stress
- Ultrasound may show polycystic ovarian morphology despite normal gonadotropins
- Tubal factor infertility
- Endometriosis
- Uterine abnormalities
For Men
- Obstructive causes (normal FSH indicates normal spermatogenesis) 2, 1
- Consider transrectal ultrasound if ejaculatory duct obstruction suspected
- Scrotal ultrasonography to evaluate for varicocele
- Functional abnormalities of sperm
- Genetic causes despite normal hormones
Treatment Approaches
For Women with Normal FSH/LH
- Address underlying causes of functional hypothalamic amenorrhea 2:
- Increase BMI to at least 18.5 kg/m² if underweight
- Reduce excessive exercise
- Manage stress
- Consider ovulation induction if anovulatory despite normal hormones:
- Clomiphene citrate (50-100 mg daily for 5 days) 3
- Letrozole (aromatase inhibitor)
- Gonadotropin therapy if other treatments fail
For Men with Normal FSH/LH
- Lifestyle modifications 1:
- Weight loss if overweight
- Smoking cessation
- Moderate alcohol consumption
- Avoid excessive heat exposure to testes
- Treatment of varicocele if present and clinically significant
- Surgical correction of obstructive causes if identified
Assisted Reproductive Technologies
- Intrauterine insemination (IUI) if total motile sperm count >5 million 2
- In vitro fertilization (IVF) with or without intracytoplasmic sperm injection (ICSI) for:
- Unexplained infertility after failed other treatments
- Severe male factor despite normal hormones
- Female factor infertility with normal hormones
Important Considerations
- Normal FSH/LH does not guarantee normal fertility; subtle abnormalities may exist 4
- FSH values >4.5 IU/L may be associated with abnormal semen parameters despite being in "normal range"
- FSH/LH ratio ≥2 in women with normal FSH may predict lower IVF outcomes 5
- Avoid testosterone therapy in men desiring fertility as it suppresses spermatogenesis 2, 1
- Consider referral to reproductive endocrinologist if no pregnancy after 6 months of appropriate therapy
When to Consider Additional Testing
- Genetic testing in men with severe oligospermia despite normal hormones 1
- Pituitary MRI if prolactin elevated or very low testosterone (<150 ng/dL) with low/normal LH 2
- Laparoscopy if endometriosis suspected in women with normal hormones
Normal gonadotropin levels narrow the differential diagnosis but do not eliminate the need for thorough evaluation of both partners to identify the cause of infertility.