Testosterone, Total and Free

Synonym/Acronym:
N/A

Rationale
To evaluate testosterone to assist in identification of disorders related to early puberty, late puberty, and infertility while assessing gonadal and adrenal function.

Patient Preparation
There are no food, fluid, activity, or medication restrictions unless by medical direction.

Normal Findings
Method: HPLC/tandem MS for total and immunochemiluminometric assay (ICMA) for free testosterone.


Total Testosterone
AgeConventional UnitsSI Units (Conventional Units × 0.0347)
Newborn
 Male75–400 ng/dL2.6–13.9 nmol/L
 Female16–44 ng/dL0.56–1.53 nmol/L
1–5 mo
 MaleLess than 300 ng/dLLess than 10.41 nmol/L
 FemaleLess than 20 ng/dLLess than 0.69 nmol/L
6–11 mo
 MaleLess than 40 ng/dLLess than 1.39 nmol/L
 FemaleLess than 9 ng/dLLess than 0.31 nmol/L
1–5 yr
 Male and femaleLess than 20 ng/dLLess than 0.69 nmol/L
6–7 yr
 MaleLess than 20 ng/dLLess than 0.69 nmol/L
 FemaleLess than 10 ng/dLLess than 0.35 nmol/L
8–10 yr
 Male2–25 ng/dL0.07–0.87 nmol/L
 Female1–30 ng/dL0.04–1 nmol/L
11–12 yr
 MaleLess than 350 ng/dLLess than 12.1 nmol/L
 FemaleLess than 50 ng/dLLess than 1.74 nmol/L
13–15 yr
 Male15–500 ng/dL0.52–17.35 nmol/L
 FemaleLess than 50 ng/dLLess than 1.74 nmol/L
Adult
 Male241–827 ng/dL8.36–28.7 nmol/L
 Female15–70 ng/dL0.52–2.43 nmol/L
Older adult
 Male300–720 ng/dL10.41–24.98
 Female5–32 ng/dL0.17–1.11
Post menopausal levels are about half the normal adult level for females; levels in women who are pregnant are three to four times the normal adult level for females who are not pregnant.

Free Testosterone
AgeConventional UnitsSI Units (Conventional Units × 3.47)
1–12 yr
 Male and femaleLess than 2 pg/mLLess than 6.94 pmol/L
12–14 yr
 MaleLess than 60 pg/mLLess than 208 pmol/L
 FemaleLess than 2 pg/mLLess than 6.94 pmol/L
14–18 yr
 Male4–100 pg/mL13.88–347 pmol/L
 FemaleLess than 10 pg/mLLess than 34.7 pmol/L
Adult
 Male50–224 pg/mL173.5–777.28 pmol/L
 Female1–8.5 pg/mL3.47–29.5 pmol/L
Older adult
 Male5–75 pg/mL17.35–260.25 pmol/L
 Female1–8.5 pg/mL3.47–29.5 pmol/L

Critical Findings and Potential Interventions
N/A

Overview

(Study type: Blood collected in a red-, red/gray-, or green-top [heparin] tube; related body system: Endocrine and Reproductive systems.) Testosterone is the major androgen responsible for sexual differentiation. In males, testosterone is made by the Leydig cells in the testicles and is responsible for spermatogenesis and the development of secondary sex characteristics. In females, the ovary and adrenal gland secrete small amounts of this hormone; however, most of the testosterone in females comes from the metabolism of androstenedione. Testosterone levels have a slight diurnal variation with the highest levels occurring around 0800 and lowest levels around 2000. Measurements of total testosterone levels are used most often in evaluating suspected hormone imbalances. Free testosterone is the active form of the hormone. It is used in conjunction with total testosterone to evaluate hormone levels in conditions known to alter the effectiveness of testosterone-binding protein, also called sex hormone–binding globulin, or SHBG. Alterations in the affinity of SHBG to bind free testosterone are known to occur with obesity, liver disease, and hyperthyroidism. In males, a testicular, adrenal, or pituitary tumor can cause an overabundance of testosterone, triggering precocious puberty. In females, adrenal tumors, hyperplasia, and medications can cause an overabundance of this hormone, resulting in masculinization or hirsutism.

Indications

  • Assist in the diagnosis of hypergonadism.
  • Assist in the diagnosis of male sexual precocity before age 10.
  • Distinguish between primary and secondary hypogonadism.
  • Evaluate hirsutism.
  • Evaluate male infertility.

Interfering Factors

Factors that may alter the results of the study

  • Drugs and other substances that may increase testosterone levels include barbiturates, bromocriptine, cimetidine, flutamide, gonadotropin, levonorgestrel, mifepristone, moclobemide, nafarelin (males), nilutamide, oral contraceptives, rifampin, and tamoxifen.
  • Drugs and other substances that may decrease testosterone levels include cyclophosphamide, cyproterone, danazol, dexamethasone, diethylstilbestrol, digoxin, D-Trp-6-LHRH, fenoldopam, goserelin, ketoconazole, leuprolide, magnesium sulfate, medroxyprogesterone, methylprednisone, oral contraceptives, pravastatin, prednisone, pyridoglutethimide, spironolactone, tetracycline, and thioridazine.

Potential Medical Diagnosis: Clinical Significance of Results

Increased In:

  • Adrenal hyperplasia (oversecretion of the androgen precursor dehydroepiandrosterone [DHEA])
  • Adrenocortical tumors (oversecretion of the androgen precursor DHEA)
  • Hirsutism (any condition that results in increased production of testosterone or its precursors)
  • Hyperthyroidism (high thyroxine levels increase the production of sex hormone–binding protein, which increases measured levels of total testosterone)
  • Idiopathic sexual precocity (related to stimulation of testosterone production by elevated levels of luteinizing hormone)
  • Polycystic ovaries (high estrogen levels increase the production of sex hormone–binding protein, which increases measured levels of total testosterone)
  • Syndrome of androgen resistance
  • Testicular or extragonadal tumors (related to excessive secretion of testosterone)
  • Trophoblastic tumors during pregnancy
  • Virilizing ovarian tumors

Decreased In:

  • Anovulation
  • Cryptorchidism (related to dysfunctional testes)
  • Delayed puberty
  • Down syndrome (related to diminished or dysfunctional testes)
  • Excessive alcohol intake (alcohol inhibits secretion of testosterone)
  • Hepatic insufficiency (related to decreased binding protein and reflects decreased measured levels of total testosterone)
  • Impotence (decreased testosterone levels can result in impotence)
  • Klinefelter syndrome (chromosome abnormality XXY associated with testicular failure)
  • Malnutrition
  • Myotonic dystrophy (related to testicular atrophy)
  • Orchiectomy (testosterone production occurs in the testes)
  • Primary and secondary hypogonadism
  • Primary and secondary hypopituitarism
  • Uremia

Nursing Implications

Potential Nursing Problems Assessment and Nursing Diagnosis

ProblemsSigns and Symptoms
Body image (related to altered male sexual development secondary to lack of testosterone) Negative verbalization of physical appearance and lack of male attributes, preoccupation with lack of physical body changes, distress and refusal to talk about appearance, negative verbalization about physical appearance
Sexuality (related to insufficient testosterone level) Delayed puberty, poor development of muscle mass, minimal body hair, insufficient penile and testicle growth, gynecomastia (breast development), arms and legs grow faster than the body trunk, erectile dysfunction, infertility, osteoporosis

Before the Study: Planning and Implementation

Teaching the Patient What to Expect

  • Inform the patient this test can assist with evaluating hormone levels.
  • Explain that a blood sample is needed for the test.

After the Study: Potential Nursing Actions

Treatment Considerations

  • Body Image: Assess the patient's perception of physical appearance. Note the frequency of negative comments about lack of male attributes associated with physical appearance. Assist in the identification of positive coping strategies to address feelings of inadequacy. Provide reassurance that physical appearance may change with testosterone therapy, and provide a referral to local support groups.
  • Sexuality: Explain the importance of testosterone replacement therapy; administer prescribed testosterone replacement medication.

Followup Evaluation and Desired Outcomes

  • Understands that the lack of development of male attributes is associated with inadequate testosterone and that hormonal therapy may support male attribute development.
  • Agrees to counseling associated with concerns related to erectile dysfunction and intimacy.

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