Pediatric Urology Academy

Amin Afrasiabi, MD, Pediatric Urologist
  • 0.0 (0)
  • Medicine
  • Updated Weekly

Pediatric Urology Academy is an evidence-based educational podcast hosted by Amin Afrasiabi, MD, Pediatric Urologist. Each episode explores pediatric urology through clinical cases, landmark studies, practical decision-making, surgical principles, and emerging research. Topics include posterior urethral valves, vesicoureteral reflux, hydronephrosis, UPJO, megaureter, neurogenic bladder, hypospadias, disorders of sexual development, pediatric stone disease, and reconstructive surgery. Designed for pediatric urologists, urologists, residents, fellows, and healthcare professionals worldwide.

  1. 15h ago

    Season 6, Episode 12 — Partial Androgen Insensitivity Syndrome: Why Partial Receptor Function Produces an Unpredictable Phenotype

    Two children can carry the same androgen receptor variant and still develop very different genital phenotypes. That is the central problem in partial androgen insensitivity syndrome. In this episode of Pediatric Urology Academy, we examine PAIS as a threshold disorder of androgen signaling rather than simply a milder form of complete androgen insensitivity. We explore: • why partial receptor function does not produce a uniform “partial” phenotype• how different tissues require different levels of androgen receptor activity• why testosterone may be normal or elevated despite inadequate virilization• how PAIS overlaps with gonadal dysgenesis, SRD5A2 deficiency, HSD17B3 deficiency, and other 46,XY DSDs• why even identical AR variants can produce markedly different phenotypes• how receptor expression, splicing, regulatory DNA, co-regulators, and other genes may modify androgen response• why a PAIS-like phenotype without a coding AR variant should not automatically be labeled PAIS• what androgen treatment can—and cannot—tell us about residual receptor function• why puberty acts as another physiological stress test• how gonadal management, tumor risk, fertility, reconstruction, and autonomy must be individualized The central framework: One receptor. Multiple tissue thresholds. Partial receptor function does not produce one predictable phenotype. Season 6 — Differences of Sex Development: Reconstruct the Biology Hosted by Amin Afrasiabi, MDPediatric Urology Academy

    Season 6, Episode 12 — Partial Androgen Insensitivity Syndrome: Why Partial Receptor Function Produces an Unpredictable Phenotype

  2. 1d ago

    Season 6, Episode 11 — Complete Androgen Insensitivity Syndrome: Testosterone Without a Biological Audience

    A 46,XY child can have testes, no uterus, female-typical external genitalia, and normal or even high testosterone. The androgen is present. The target cannot respond. In this episode of Pediatric Urology Academy, we examine complete androgen insensitivity syndrome as a disorder of androgen action rather than androgen production. We explore: • why normal testosterone does not guarantee normal androgen effect• how preserved AMH explains Müllerian regression despite female-typical external genitalia• why Wolffian structures are often absent or poorly developed• how the androgen receptor converts hormone binding into gene transcription• why normal breast development can coexist with sparse pubic and axillary hair• how CAIS differs from Leydig cell hypoplasia, HSD17B3 deficiency, and SRD5A2 deficiency• why an inguinal testis in a phenotypic girl should trigger diagnostic reconsideration• how current evidence has changed the timing of gonadectomy• why prepubertal tumor risk appears low, but surveillance cannot eliminate uncertainty• how retained gonads, spontaneous puberty, hormone replacement, autonomy, and fertility preservation shape shared decision-making The central framework: The hormone is made. The target receives it. But the receptor cannot convert the signal into biological action. Season 6 — Differences of Sex Development: Reconstruct the Biology Hosted by Amin Afrasiabi, MDPediatric Urology Academy

    Season 6, Episode 11 — Complete Androgen Insensitivity Syndrome: Testosterone Without a Biological Audience

  3. 2d ago

    Season 6, Episode 10 — The Backdoor Androgen Pathway: How the Fetus Can Reach DHT Without the Main Road

    The classic androgen pathway is not the whole story. A fetus can generate androgen effect through an alternative biochemical route that bypasses testosterone as the obligatory intermediate. In this episode of Pediatric Urology Academy, we examine the human backdoor androgen pathway and why it matters when genotype, serum hormones, and genital phenotype do not seem to fit neatly together. We explore: • how fetal tissues can reach DHT through more than one biochemical route• why serum testosterone does not fully represent androgen exposure at the target tissue• the role of androsterone in human fetal backdoor androgen biology• how AKR1C2 and AKR1C4 defects can produce 46,XY undervirilization• why POR deficiency can produce both 46,XY undervirilization and 46,XX virilization• how excess steroid precursors can be redirected through alternative androgen pathways• why placenta, adrenal, liver, testis, and peripheral tissues should be viewed as a distributed fetal steroidogenic system• when urinary steroid profiling and molecular testing become particularly useful• why the backdoor pathway should be used to localize biology, not as a catch-all diagnosis The central framework: The classic pathway is the main road. The backdoor pathway is the side road. External genital development reflects the total androgen signal that reached the target during the critical developmental window. Season 6 — Differences of Sex Development: Reconstruct the Biology Hosted by Amin Afrasiabi, MDPediatric Urology Academy

    Season 6, Episode 10 — The Backdoor Androgen Pathway: How the Fetus Can Reach DHT Without the Main Road

  4. 3d ago

    Season 6, Episode 9 — Testosterone Is Not DHT: SRD5A2 Deficiency and Androgen Amplification

    A 46,XY child can have testes, no uterus, preserved Wolffian structures—and markedly undervirilized external genitalia. The testosterone may even be normal. The missing signal is DHT. In this episode of Pediatric Urology Academy, we examine SRD5A2 deficiency as a disorder of tissue-specific androgen amplification rather than simply “low androgen.” We explore: • why testosterone and DHT are not biologically interchangeable• how Wolffian structures can masculinize while external genital virilization remains incomplete• why SRD5A2 acts as a local androgen amplifier during fetal development• how the testosterone-to-DHT ratio helps localize the defect, but cannot reliably confirm or exclude it• why hCG stimulation and urinary steroid profiling can add diagnostic information• how SRD5A2 deficiency differs from HSD17B3 deficiency and complete androgen insensitivity• why substantial virilization may occur at puberty despite severe fetal undervirilization• why puberty cannot recreate developmental windows that were missed in fetal life• what current evidence suggests about fertility, gonadal preservation, and tumor risk The central framework: Testosterone delivers the androgen signal. DHT amplifies it in selected tissues. Season 6 — Differences of Sex Development: Reconstruct the Biology Hosted by Amin Afrasiabi, MDPediatric Urology Academy

    Season 6, Episode 9 — Testosterone Is Not DHT: SRD5A2 Deficiency and Androgen Amplification

  5. 4d ago

    Season 6, Episode 8 — HSD17B3 Deficiency: When the Testis Makes the Precursor but Not Enough Testosterone

    A 46,XY child can have testes, no uterus, and markedly undervirilized external genitalia—then virilize substantially at puberty. The explanation lies inside the steroid pathway. In this episode of Pediatric Urology Academy, we examine HSD17B3 deficiency through a precursor–product framework: androstenedione is produced, but its conversion to testosterone is impaired. We explore: • why preserved Müllerian regression does not prove normal testosterone synthesis• how androstenedione identifies the biochemical bottleneck• why the testosterone-to-androstenedione ratio is useful but not diagnostic• how hCG stimulation and mini-puberty can expose the defect• why puberty can partially bypass the fetal metabolic block• how HSD17B3 deficiency differs from complete androgen insensitivity and SRD5A2 deficiency• why genotype does not perfectly predict phenotype• the evolving controversy around gonadal preservation, tumor risk, puberty suppression, and fertility The central framework: Do not measure only the final hormone. Follow the substrate. Follow the product. Find where the pathway stopped. Season 6 — Differences of Sex Development: Reconstruct the Biology Hosted by Amin Afrasiabi, MDPediatric Urology Academy

    Season 6, Episode 8 — HSD17B3 Deficiency: When the Testis Makes the Precursor but Not Enough Testosterone

  6. 5d ago

    Season 6, Episode 7 — Leydig Cell Hypoplasia: A Testis That Cannot Hear hCG or LH

    The testes are present. Müllerian structures are absent. Yet the external genitalia may be profoundly undervirilized. That combination localizes the problem. In this episode of Pediatric Urology Academy, we examine Leydig cell hypoplasia through one of the most useful frameworks in 46,XY DSD: a single receptor is challenged during two different developmental eras. Placental hCG tests the fetal Leydig cell. Pituitary LH tests it again at puberty. We explore: • how LHCGR dysfunction disrupts fetal testosterone production while preserving Sertoli-cell AMH function• why absent Müllerian structures can coexist with severe undervirilization• how Leydig cell hypoplasia differs from gonadal dysgenesis and androgen insensitivity• why high LH with low testosterone represents a failed Leydig response rather than simply “hypogonadism”• how hCG stimulation testing should—and should not—be interpreted• why residual LHCGR activity produces a continuum of phenotypes• how fetal genital phenotype and pubertal endocrine function interrogate the same receptor under different physiological demands• where molecular testing adds information beyond endocrine testing The central framework: One receptor.Two developmental eras. hCG writes the fetal phenotype. LH reveals what remains at puberty. Season 6 — Differences of Sex Development: Reconstruct the Biology Hosted by Amin Afrasiabi, MDPediatric Urology Academy

    Season 6, Episode 7 — Leydig Cell Hypoplasia: A Testis That Cannot Hear hCG or LH

  7. 6d ago

    Season 6, Episode 6 — Testicular Regression: Reconstructing When the Testis Disappeared

    A boy can have male-typical external genitalia, no Müllerian structures, a vas deferens—and no testis. That is not a contradiction. It is a developmental timeline. In this episode of Pediatric Urology Academy, we examine testicular regression syndrome as a problem of reconstructing when a previously functioning fetal testis was lost. We explore: • how Müllerian anatomy, Wolffian structures, and external virilization act as developmental timestamps• why testicular regression differs fundamentally from true agenesis• how intrauterine torsion or vascular injury may leave a fibrotic nubbin• how AMH, inhibin B, and gonadotropins help evaluate bilateral nonpalpable testes• why contralateral compensatory hypertrophy is a clue, not proof• how operative anatomy distinguishes blind-ending vessels, vanishing testis, and distal remnants• why a testicular nubbin is biologically different from a dysgenetic gonad• why hypoplasia, hypotrophy, atrophy, and regression should not be used interchangeably The central framework is simple: Phenotype is a developmental flight recorder. Read the Müllerian structures. Read the Wolffian structures. Read the genital phenotype. Then reconstruct when the testis disappeared. Season 6 — Differences of Sex Development: Reconstruct the Biology Hosted by Amin Afrasiabi, MDPediatric Urology Academy

    Season 6, Episode 6 — Testicular Regression: Reconstructing When the Testis Disappeared

  8. Oct 5

    Season 6, Episode 5 — Complete vs Partial Gonadal Dysgenesis: How Much Testis Was Actually Built?

    A 46,XY child can have female-typical external genitalia and streak gonads. Another can have hypospadias, partial Müllerian regression, a palpable gonad, and spontaneous virilization at puberty. The difference is not simply “more or less testosterone.” It is how much functional testicular tissue was actually built. In this episode of Pediatric Urology Academy, we reconstruct complete and partial gonadal dysgenesis as disorders of testicular development rather than isolated endocrine failure. We examine: • why gonadal dysgenesis differs fundamentally from androgen synthesis defects and androgen insensitivity• how Sertoli, Leydig, and germ-cell function can survive to different degrees• why fetal testicular failure does not always predict pubertal endocrine failure• how genes including SRY, SOX9, NR5A1, MAP3K1, and WT1 fit into the developmental framework• why dysgenetic gonads require careful assessment of germ-cell tumor risk• why imaging, tumor markers, and limited biopsy cannot completely eliminate uncertainty• how to balance endocrine value, fertility potential, gonadal position, histology, and oncologic risk The central question is not: “Is there a testis?” It is: “How much testis was ever built?” Season 6 — Differences of Sex Development: Reconstruct the Biology Hosted by Amin Afrasiabi, MDPediatric Urology Academy

    Season 6, Episode 5 — Complete vs Partial Gonadal Dysgenesis: How Much Testis Was Actually Built?
See All (77)

About

Pediatric Urology Academy is an evidence-based educational podcast hosted by Amin Afrasiabi, MD, Pediatric Urologist. Each episode explores pediatric urology through clinical cases, landmark studies, practical decision-making, surgical principles, and emerging research. Topics include posterior urethral valves, vesicoureteral reflux, hydronephrosis, UPJO, megaureter, neurogenic bladder, hypospadias, disorders of sexual development, pediatric stone disease, and reconstructive surgery. Designed for pediatric urologists, urologists, residents, fellows, and healthcare professionals worldwide.

Information

  • Creator
    Amin Afrasiabi, MD, Pediatric Urologist
  • Years Active
    2026
  • Episodes
    77
  • Rating
    Clean
  • Copyright
    © Amin Afrasiabi, MD, Pediatric Urologist
  • Show Website
    Pediatric Urology Academy