The Virginia Transman

Below I’m going to post some information regarding testosterone. The information comes from LabCorp which is where my primary care physician gets their information and has their laboratory work done. I’m posting it here just as reference because to my knowledge, only physicians have direct access to this information.

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Testosterone

Introduction

Testosterone is a steroid hormone that is commonly measured for various diagnostic purposes. Testosterone results can be used to evaluate hypogonadal men for primary or secondary testicular dysfunction. In men, low levels of testosterone are a possible cause of reduced fertility or lack of libido. In women, testosterone results can be used to evaluate conditions of androgen excess, such as PCOS (polycystic ovarian syndrome), hirsutism, suspected androgen-producing neoplasm, and conditions that may affect fertility, such as anovulation or amenorrhea with virilization. Testosterone measurement may also be helpful in menopausal women with suspected testosterone deficiency. Testosterone results in children can be used to aid in the diagnosis and treatment of premature puberty, genetic diseases - such as congenital adrenal hyperplasia - and over-virilization or under-virilization at birth.

Recent research suggests that maintaining the appropriate levels of testosterone may benefit men with osteoporosis, type 2 diabetes, cardiovascular disease, obesity and depression. Androgen replacement therapy in postmenopausal women has also been studied as a means of boosting bone density and muscle mass. The recent epidemic of obesity in children has led to an increase in the assessment of androgen status in these patients because obesity has been associated with precocious puberty.

Commonly used methods for testosterone measurements in the clinical laboratory include direct immunoassays (RIA, ELISA, ICMA, EIA, ECLIA, etc), immunoassays after extraction and chromatography, and (more recently) mass spectrometry methods. Each method offers unique strengths and shortcomings, and the choice of methods depends on the physician’s intended use and the performing laboratory’s technical expertise.

Testosterone Testing Recommendations

Historically, testosterone levels were primarily used in the work-up of men suspected of hypogonadism and in gender assignment for newborns with ambiguous genitalia. The Endocrine Society and the American Society for Andrology recommend using the total testosterone measurement, preferably obtained on more than one morning sample - as a screening test for hypogonadism in men - and concluded that most direct immunoassays distinguish between testosterone concentrations found in classic hypogonadism and normal levels. Monitoring hypogonadal males during testosterone replacement therapy, however, requires more sensitive and accurate assays.

Due to its expanded clinical applications, measurements of testosterone levels in women and children has increased in recent years. Its most common application in women is as an aid in the diagnosis of hyperandrogenic states. It is reported that most direct immunoassays are adequate for identifying, but not accurately quantifying elevated testosterone in women.

The Endocrine Society recommends that testosterone determination in children be performed using assays with sufficient sensitivity and in conjunction with appropriate reference intervals. Populations with low testosterone concentrations, such as women, children, and hypogonadal males, require more attention to the assay’s analytical sensitivity and specificity. One of the methods that may offer an appropriate level of sensitivity and specificity for these populations is high-pressure liquid chromatography and tandem mass spectrometry (HPLC/MS-MS).

Testosterone Assay Standardization

Another concern regarding laboratory measurements of testosterone is the lack of standardization among methodologies. In early 2010, a group of professional associations, government agencies, and commercial entities met to discuss issues regarding the need for accurate testosterone assay standardization, including a consensus effort regarding the need for accurate testosterone testing. The consensus effort is being led by the Centers for Disease Control and Prevention (CDC). In addition to LabCorp, organizations endorsing the consensus effort for accurate testosterone testing include:

• American Association for Clinical Chemistry
• American Association of Clinical Endocrinologists
• American Society for Bone and Mineral Research
• American Society for Reproductive Medicine
• American Urological Association
• Androgen Excess and PCOS Society
• Association of Public Health Laboratories 
• North American Menopause Society
• Pediatric Endocrine Society
• The Endocrine Society

The new CDC Hormone Standardization (HoSt) project will be issuing annual certificates to laboratories that demonstrate performance within the established criteria, enabling harmonization of testosterone test results across laboratories and methodologies.

LabCorp Testosterone Test Options

LabCorp offers a comprehensive menu of testosterone methods to meet the testing needs for various patient conditions. In addition to a next-generation direct immunoassay from Roche (ECLIA), LabCorp also offers a highly sensitive and specific high-pressure liquid chromatography and tandem mass spectrometry (HPLC/MS-MS) method. Both methodologies are being evaluated as part of the CDC HoSt Project for testosterone standardization.

The direct ECLIA testosterone immunoassay (004226) is appropriate for use as an aid in screening for androgen dysfunctions in adult males. It is sufficiently sensitive and accurate for this purpose and allows fast turnaround time for test results.

The LC/MS-MS assay (070001) can aid in the diagnosis of androgen dysfunction in females and children as well as for monitoring male patients diagnosed with hypogonadism. It is a more sensitive and specific method when measuring very low testosterone concentrations when compared to immunoassay.

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Total Testosterone

Premature Infants - Males

26-28 Weeks, Day 4 (59.0-125.0 ng/dL)

31-35 Weeks, Day 4 (37.0-198.0 ng/dL)

Premature Infants - Females

26-28 Weeks, Day 4 (5.0-16.0 ng/dL)

31-35 Weeks, Day 4 (5.0-22.0 ng/dL)

Full-term Infants - Males

Newborn (75.0-400.0 ng/dL)

1-7 Months (Levels decrease rapidly the first week to 20.0-50.0 ng/dL, then increase to 60.0-400.0 ng/dL (Mean = 190) between 20-60 days. Levels then decline to prepubertal range of <2.5-10.0 by seven months.)

Full-term Infants - Females

Newborn (20.0-64.0 ng/dL)

1-7 Months (Levels decrease during the first month to <10.0 ng/dL, and remain there until puberty.)

Prepubertal Children - Males

1-10 Years (<2.5-10.0 ng/dL)

Prepubertal Children - Females

1-9 Years (<2.5-10.0 ng/dL)

Puberty - Males

9.8-14.5 Years (18.0-150.0 ng/dL)

10.7-15.4 Years (100.0-320.0 ng/dL)

11.8-16.2 Years (200.0-620.0 ng/dL)

12.8-17.3 Years (350.0-970.0 ng/dL)

Puberty - Females

9.2-13.7 Years (7.0-28.0 ng/dL)

10.0-14.4 Years (15.0-35.0 ng/dL)

10.7-15.6 Years (13.0-32.0 ng/dL)

11.8-18.6 Years (20.0-38.0 ng/dL)

Adults - Males

18+ Years (350.0-1030.0 ng/dL)

Adults - Females

Premenopausal (10.0-55.0 ng/dL)

Postmenopausal (7.0-40.0 ng/dL)

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Sex Hormone-binding Globulin Serum

Reference Interval - Male

20-49 Years (16.5-55.9 nmol/L)

49+ Years (19.3-76.4 nmol/L)

Reference Interval - Female

20-49 Years (24.6-122.0 nmol/L)

49+ Years (17.3-125.0 nmol/L)

Use: Levels of SHBG are under the positive control of estrogens and thyroid hormones, and are suppressed by androgens. These influences dynamically control the liver synthesis of this carrier protein. Decreased levels of SHBG are frequently seen in hirsutism, virilization, obese postmenopausal women, and in women with diffuse hair loss, increased levels may be present in cases of hyperthyroidism, testicular feminization, cirrhosis, male hypogonadism, pregnancy, women using oral contraceptives, and prepubertal children.

Additional Information: Sex hormone-binding Globulin (SHBG) is the blood transport protein for testosterone and estradiol. It is a large glycoprotein with a molecular weight of about 95 kD and exists as a homodimer composed of two identical subunits. Each subunit contains two disulfide bridges.