α-Subunit, Free (Endocrine Sciences)

TEST: 140269
Test number copied
CPT: 83520
Print Share

Synonyms

  • Pituitary Glycoproteins, Alpha Subunit

Expected Turnaround Time

6 - 10 days

Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.

Specimen Requirements

Specimen

Serum, frozen

Volume

1 mL

Minimum Volume

0.25 mL (Note: This volume does not allow for repeat testing.)

Container

Serum from gel-barrier tube, serum from red-top tube, or serum from transfer tube

Collection

Transfer the serum into a Labcorp PP transpak frozen purple tube with screw cap (Labcorp No. 49482). Freeze immediately and maintain frozen until tested. To avoid delays in turnaround time when requesting multiple tests on frozen samples, please submit separate frozen specimens for each test requested.

Storage Instructions

Freeze.

Stability Requirements

Temperature

Period

Room temperature

1 day

Refrigerated

1 day

Frozen

200 days

Test Details

Use

Tumor marker

Methodology

Immunochemiluminometric assay (ICMA)

Reference Interval

• Male:

− 20 to 44 years: <0.55 ng/mL

− 45 to 54 years: <0.86 ng/mL

− 55 to 64 years: <1.37 ng/mL

− 65 to 94 years: <2.13 ng/mL

• Female:

− 20 to 44 years (premenopausal): <1.02 ng/mL

− 45 to 59 years (perimenopausal): <2.34 ng/mL

− 60 to 99 years (postmenopausal): <3.56 ng/mL

Additional Information

The α-subunits of human pituitary glycoprotein hormones TSH, FSH, LH, and the placental hormone hCG have similar amino sequences and are immunologically indistinguishable.1 The β-subunits are unique and responsible for the biological and immunological specificity of the intact hormones. Levels of free α-subunit increase during normal pregnancy.2 Measurement of free α-subunit can be of clinical utility in the assessment of abnormal pregnancy, gestational trophoblastic disease, and some nontrophoblastic malignancies.3,4 Elevated concentrations of α subunit have been associated with testicular cancer,5 pituitary adenomas,6 and malignant endocrine gastroenteropancreatic tumors, including Zollinger-Ellison syndrome.7,8

Footnotes

1. Pierce JG, Parsons TF. Glycoprotein hormones: Structure and function. Annu Rev Biochem. 1981; 50:465-495 (review). 6267989
2. Benveniste R, Scommegha A. Human chorionic gonadotropin alpha subunit in pregnancy. Am J Obstet Gynecol. 1981; 141(8):952-961. 6172038
3. Hussa RO. Clinical utility of human chorionic gonadotropin and alpha subunit measurements. Obstet Gynecol. 1982; 60(1):1-12 (review). 6283446
4. Cole LA. hCG, its free subunits and its metabolites: Roles in pregnancy and trophoblastic disease. J Reprod Med. 1998; 43(1):3-10 (review). 9475142
5. Madersbacher S, Klieber R, Mann K, et al. Free alpha-subunit, free beta-subunit of human chorionic gonadotropin (hCG), and intact hCG in sera of healthy individuals and testicular cancer patients. Clin Chem. 1992; 38(3):370-376. 1372196
6. Preissner CM, Klee GG, Scheithauer BW, et al. Free alpha subunit of the pituitary glycoprotein hormones. Measurement in serum and tissue of patients with pituitary tumors. Am J Clin Pathol. 1990; 94(4):417-421. 1699408
7. Grossmann M, Trautmann ME, Poertl S, et al. Alpha subunit and human chorionic gonadotropin-beta immunoreactivity in patients with malignant endocrine gastroenteropancreatic tumours. Eur J Clin Invest. 1994; 24(2):131-136. 7515807
8. Bardram L, Agner T, Hagen C, et al. Levels of alpha-subunits of gonadotropins can be increased in Zollinger-Ellison syndrome, both in patients with malignant tumours and with apparently benign disease. Acta Endocrinol (Copenh). 1988; 118(1):135-141.3389044

LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
140269 Alpha Subunit (Free) 30316-4 140271 Alpha Subunit (Free) ng/mL 30316-4