351 ‒ Male fertility: optimizing reproductive health, treating infertility, & navigating TRT

KEYPOINTS

• 01

  Conception is a brutal elimination race

  Of about 100 million ejaculated sperm, roughly 5 million get through the cervix past acidic vaginal fluid (pH about 5), only 100–500 reach the fallopian tube, and one reaches the egg. Turek describes research (from a company he consults for) suggesting sperm advance in waves, like a phalanx: early waves soak up the uterus's active immune response so later sperm can get through. Failing at this may explain some infertility.

• 02

  Sperm take about 74 days to make, so changes show up months later

  Turek's deuterated-water study found an average of 74 days from production to ejaculation (some men as fast as 42). That includes about two weeks maturing in the epididymis, a ~35 ft tube where sperm learn to swim forward and to 'smell' follicular fluid at one part per billion. Expect any intervention to take at least 2.5 months to show results, and about 90 days for a full turnover. After varicocele repair, the average time to conception was about seven months.

• 03

  Sperm drive evolution and carry the father's environment to the next generation

  Sperm stem cells divide throughout life and pick up mutations and epigenetic changes, about 50 new mutations per generation on average, with many more from older fathers. Roughly half affect brain development. About 98% of normal sperm have the right number of chromosomes, and the epididymis seems to filter out defective ones: testicular sperm show 2–3 times more abnormalities than ejaculated sperm.

• 04

  Have sex in the days before ovulation, not after

  Sperm can wait in the oviduct for days, but an ovulated egg survives only about 8 hours. In a NEJM diary study of about 700 couples, sex every other day before ovulation gave the best results, and waiting until ovulation produced only about 20% of conceptions. Turek says 80% of natural conceptions come from sex in the days leading up to ovulation. For conception he advises sex every other day. For a semen analysis, abstain 2–4 days: count rises with abstinence but motility falls.

• 05

  A male workup: thorough history, expert exam, two semen analyses, hormones

  Only about 23% of men get a formal evaluation before couples go to IVF in North America. Turek uses a 200-question history, which he says matters most. On exam he checks for varicocele, cancer, and a congenitally absent vas deferens (about 1 in 500 men), which he can feel and which signals a likely cystic fibrosis carrier. Semen results vary 50–100% between samples, so get at least two about three weeks apart. He reads the results like a poker hand: low motility alone points to short-term exposures, while low count plus low motility suggests something more severe.

• 06

  Testosterone therapy usually wipes out sperm production

  Exogenous testosterone shuts down LH and FSH. Turek puts the chance of zero sperm at 95% for a man on injections. Topical, nasal (three times daily) and oral (twice daily) forms are more physiologic and in his experience can preserve sperm counts. hCG and clomiphene/enclomiphene stimulate the body's own production and keep fertility. He adds clomiphene when hCG goes above about 1,500 units three times a week, which starts suppressing FSH. He has about 560 men on clomiphene and argues the FDA's rejection of enclomiphene reflects the backlash over direct-to-consumer testosterone ads.

• 07

  Thick blood is the main testosterone risk

  Exogenous testosterone raises EPO and red-cell mass. Turek sees events begin around hemoglobin 18 and definitely at 19, and warns of clots on long, dehydrating flights. Pellets last about four to six months. Rough symptom thresholds Turek cites: erections ~290 ng/dL, fertility ~300, libido ~350.

• 08

  Getting off testosterone: taper, then stimulate

  Recovery depends on dose, duration and form: continuous injections are worst, while cycling allows recovery. Turek worries that after 5–10 years function may not return; Peter's practice treats about two years as the ceiling. Turek tapers over about six weeks, with or without clomiphene, or uses hCG plus clomiphene for a faster restart. He checks testosterone about two weeks after the last dose, as the low point. Low-dose hCG (250–500 units twice weekly) alongside testosterone kept sperm normal in a 12-week study of bodybuilders, but miss doses over years and counts can crash.

• 09

  Hot tubs are among the worst things for sperm

  The testes run about 3°F cooler than the body. When infertile men stopped hot baths, total motile sperm count rose about 300% by three to four months and 600% by six. Turek estimates that 20 minutes at 104°F three times a week could take a man to zero. Saunas have about a quarter to a third of the effect (so Peter's friend's ice packs make sense), steam rooms fall in between, and cold plunges and surfing are fine.

• 10

  Other common factors

  Varicoceles (about 40% of cases) come from the left testicular vein draining uphill without valves, which Turek blames on humans standing up. Hormonal problems account for 10–15%. Genetic causes include Klinefelter syndrome and Y-chromosome deletions, which don't improve with varicocele repair and are passed to sons. Alcohol and THC act as direct toxins: THC stays in fat for weeks, and two epidemiological studies tie chronic use to testicular cancer. Type 2 diabetes and obesity also matter, and a third of type 2 diabetics have low testosterone.