II. Physiology

  1. Androgenic steroid synthesized in males, in the leydig cells of the Testis
  2. Release is stimulated by Luteinizing Hormone release from the Pituitary Gland
    1. In a negative feedback loop, Testosterone suppresses release of LF and FSH from the pituitary
  3. Mechanism
    1. Activity via Testosterone, or by its conversion to dihydrotestosterone (DHT) irreversibly by 5-alpha reductase
  4. Responsible for male sex characteristics and male reproductive function
    1. Facial hair
    2. Deep voice
    3. Muscle growth
    4. Spermatogenesis
    5. Libido

III. Pathophysiology

IV. Technique

  1. Obtain in the morning (or within 2 hours of awakening) due to circadian variation

V. Labs: Interpretation

  1. Normal Levels
    1. Male: 300 to 1000 ng/100 ml
    2. Female: <70 ng/100 ml

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Related Studies

Ontology: Testosterone (C0039601)

Definition (NCI) A synthetic form of the endogenous androgenic steroid testosterone. In vivo, testosterone is irreversibly converted to dihydrotestosterone (DHT) in target tissues by the enzyme 5-alpha reductase. Testosterone or DHT ligand-androgen receptor complexes act as transcription factor complexes, stimulating the expression of various responsive genes. DHT binds with higher affinity to androgen receptors than testosterone, activating gene expression more efficiently. In addition, testosterone is irreversibly converted to estradiol by the enzyme complex aromatase, particularly in the liver and adipose tissue. Testosterone and DHT promote the development and maintenance of male sex characteristics related to the internal and external genitalia, skeletal muscle, and hair follicles; estradiol promotes epiphyseal maturation and bone mineralization. Due to rapid metabolism by the liver, therapeutic testosterone is generally administered as an ester derivative.
Definition (NCI_NCI-GLOSS) A hormone made mainly in the testes (part of the male reproductive system). It is needed to develop and maintain male sex characteristics, such as facial hair, deep voice, and muscle growth. Testosterone may also be made in the laboratory and is used to treat certain medical conditions.
Definition (CSP) major androgenic hormone produced by the Leydig cells of the testes.
Definition (MSH) A potent androgenic steroid and major product secreted by the LEYDIG CELLS of the TESTIS. Its production is stimulated by LUTEINIZING HORMONE from the PITUITARY GLAND. In turn, testosterone exerts feedback control of the pituitary LH and FSH secretion. Depending on the tissues, testosterone can be further converted to DIHYDROTESTOSTERONE or ESTRADIOL.
Definition (PDQ) A synthetic form of the endogenous androgenic steroid testosterone. Due to rapid metabolism by the liver, therapeutic testosterone is generally administered as an ester derivative. This agent and its derivatives promote the maintenance of male sex characteristics. Check for "http://www.cancer.gov/Search/ClinicalTrialsLink.aspx?id=42926&idtype=1" active clinical trials or "http://www.cancer.gov/Search/ClinicalTrialsLink.aspx?id=42926&idtype=1&closed=1" closed clinical trials using this agent. ("http://nciterms.nci.nih.gov:80/NCIBrowser/ConceptReport.jsp?dictionary=NCI_Thesaurus&code=C862" NCI Thesaurus)
Concepts Pharmacologic Substance (T121) , Hormone (T125) , Steroid (T110)
MSH D013739
SnomedCT 109033004, 43688007
LNC LP14045-6, MTHU002002
English Testosterone, Delta4-Androsten-17beta-ol-3-one, Trans-Testosterone, therapeutic testosterone, testosterone, testosterones, testosterones (medication), testosterone (medication), TESTOSTERONE, Testosterone [Chemical/Ingredient], 17 beta Hydroxy 4 Androsten 3 one, 17-beta-Hydroxy-4-Androsten-3-one, Androst-4-en-17beta-ol-3-one, Testosterone product, Total testosterone, Testosterone (substance), Testosterone preparation (product), Testosterone preparation, TESTO, Testosterone preparation (substance), Delta4-androsten-17beta-ol-3-one, (17Beta)-17-hydroxyandrost-4-en-3-one, Therapeutic Testosterone
Swedish Testosteron
Czech testosteron
Finnish Testosteroni
French 17bêta-Hydroxy-androst-4-én-3-one, Testostérone
Italian 17 beta-hydroxy-4-androstene-3-one, Testosterone
Japanese テストステロン
Spanish preparado con testosterona (producto), testosterona (producto), preparado con testosterona, preparado de testosterona (producto), preparado de testosterona (sustancia), preparado de testosterona, testosterona (sustancia), testosterona, Testosterona
Polish Testosteron
Norwegian Testosteron, 17-beta-hydroksi-4-androsten-3-on
German Testosteron
Portuguese Testosterona

Ontology: Total Testosterone Measurement (C0202227)

Definition (NCI_CDISC) A measurement of the total (free and bound) testosterone in a biological specimen.
Definition (NCI) The determination of the amount of free and bound testosterone present in a sample.
Concepts Laboratory Procedure (T059)
SnomedCT 85470006
CPT 84403
English Testosterone; total, Total Testosterone Measurement, total testosterone measurement, testosterone total, ASSAY OF TESTOSTERONE TOTAL, Measurement of total testosterone, Testosterone, Total Testosterone, TESTOS, Testosterone measurement, total, Testosterone measurement, total (procedure), ASSAY OF TOTAL TESTOSTERONE, Assay of total testosterone
Spanish medición de testosterona total (procedimiento), medición de testosterona total

Ontology: Serum testosterone measurement (C0428413)

Concepts Laboratory Procedure (T059)
SnomedCT 166456008, 143792007, 270973006
English Serum testosterone, serum testosterone measurement, serum testosterone, serum testosterone measurement (lab test), levels serum testosterone, serum testosterone level, Testosterone - serum, Serum testosterone (& level), Serum testosterone (& level) (procedure), Serum Testosterone Test, Serum testosterone level, Serum testosterone measurement (procedure), Serum testosterone measurement
Dutch serum testosteron
French Testostérone sérique
German Testosteron im Serum
Italian Testosterone sierico
Portuguese Testosterona sérica
Spanish Testosterona en suero, determinación de nivel sérico de testosterona, medición sérica de testosterona (procedimiento), medición sérica de testosterona
Japanese 血清テストステロン, ケッセイテストステロン
Czech Testosteron v séru
Hungarian Szérum tesztoszteron