5-alpha-reductase deficiency
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5-alpha-reductase deficiency
Endocrine system
Adrenal gland disorders
Congenital adrenal hyperplasia
Primary adrenal insufficiency
Waterhouse-Friderichsen syndrome
Hyperaldosteronism
Adrenal cortical carcinoma
Cushing syndrome
Conn syndrome
Thyroid gland disorders
Thyroglossal duct cyst
Hyperthyroidism
Graves disease
Thyroid eye disease (NORD)
Toxic multinodular goiter
Thyroid storm
Hypothyroidism
Euthyroid sick syndrome
Hashimoto thyroiditis
Subacute granulomatous thyroiditis
Riedel thyroiditis
Postpartum thyroiditis
Thyroid cancer
Parathyroid gland disorders
Hyperparathyroidism
Hypoparathyroidism
Hypercalcemia
Hypocalcemia
Pancreatic disorders
Diabetes mellitus
Diabetic retinopathy
Diabetic nephropathy
Pituitary gland disorders
Hyperpituitarism
Pituitary adenoma
Hyperprolactinemia
Prolactinoma
Gigantism
Acromegaly
Hypopituitarism
Growth hormone deficiency
Pituitary apoplexy
Sheehan syndrome
Hypoprolactinemia
Constitutional growth delay
Diabetes insipidus
Syndrome of inappropriate antidiuretic hormone secretion (SIADH)
Gonadal dysfunction
Precocious puberty
Delayed puberty
Premature ovarian failure
Polycystic ovary syndrome
Androgen insensitivity syndrome
Kallmann syndrome
5-alpha-reductase deficiency
Polyglandular syndromes
Autoimmune polyglandular syndrome type 1 (NORD)
Endocrine tumors
Multiple endocrine neoplasia
Pancreatic neuroendocrine neoplasms
Zollinger-Ellison syndrome
Carcinoid syndrome
Pheochromocytoma
Neuroblastoma
Opsoclonus myoclonus syndrome (NORD)
Endocrine system pathology review
Adrenal insufficiency: Pathology review
Adrenal masses: Pathology review
Hyperthyroidism: Pathology review
Hypothyroidism: Pathology review
Thyroid nodules and thyroid cancer: Pathology review
Parathyroid disorders and calcium imbalance: Pathology review
Diabetes mellitus: Pathology review
Cushing syndrome and Cushing disease: Pathology review
Pituitary tumors: Pathology review
Hypopituitarism: Pathology review
Diabetes insipidus and SIADH: Pathology review
Multiple endocrine neoplasia: Pathology review
Neuroendocrine tumors of the gastrointestinal system: Pathology review
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Content Reviewers
Rishi Desai, MD, MPHContributors
Antonia Syrnioti, MD
Brittany Norton, MFA
Marisa Pedron
Tanner Marshall, MS
5α- reductase deficiency is a genetic disorder in which a protein called 5α reductase is defective or absent.
That’s an enzyme that converts the male hormone testosterone to its more potent form, called dihydrotestosterone.
One of the most important roles of dihydrotestosterone is to help male external genitalia develop in a male fetus.
Okay, normally, very early on in fetal life, male and female internal sex organs and external genitalia are undifferentiated and look identical.
Within the first few months of development, testes develop in the male fetus.
The testes start producing testosterone - a male steroid hormone that belongs to a class of hormones called androgens.
The testosterone gets released into the blood and a tiny fraction of it gets converted by 5α- reductase, which is mainly made in the skin of the genital area, into dihydrotestosterone.
Over time, dihydrotestosterone levels start rising and it affects undifferentiated genital structures.
Looking closely at these structures, at the top there’s the genital tubercle, which is a small projection.
Just below that, there's the urethral groove, which is the external opening of the urogenital sinus or the future urethra and bladder and is surrounded by the urethral folds and the labioscrotal swellings.
Now, once dihydrotestosterone reaches these structures, it makes the genital tubercle elongate into the phallus which will eventually be the penis.
The elongating genital tubercle pulls up the urethral folds which fuse in the midline, forming the spongy or penile urethra.
The tips of the urethral folds remain unfused and that forms the external urethral opening at the distal tip of the penis.
Sources
- "Robbins Basic Pathology" Elsevier (2017)
- "Harrison's Principles of Internal Medicine, Twentieth Edition (Vol.1 & Vol.2)" McGraw-Hill Education / Medical (2018)
- "Pathophysiology of Disease: An Introduction to Clinical Medicine 8E" McGraw-Hill Education / Medical (2018)
- "CURRENT Medical Diagnosis and Treatment 2020" McGraw-Hill Education / Medical (2019)
- "5-alpha-reductase deficiency: a case report" Paediatrica Indonesiana (2016)
- "Steroid 5agr-Reductase Deficiency in Man: An Inherited Form of Male Pseudohermaphroditism" Science (1974)
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