Turnaround Time: 6 -10 days
CPT Code:


Test Type: 1 mL Serum (preferred) or plasma, frozen
Stability Time:



Room temperature

1 day


1 day


200 days

Reference Range:

• 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


Tumor marker.

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

1. Pierce JG, Parsons TF. Glycoprotein hormones: Structure and function. Annu Rev Biochem. 1981; 50:465-495 (review). PubMed 6267989

2. Benveniste R, Scommegha A. Human chorionic gonadotropin alpha subunit in pregnancy. Am J Obstet Gynecol. 1981; 141(8):952-961. PubMed 6172038

3. Hussa RO. Clinical utility of human chorionic gonadotropin and alpha subunit measurements. Obstet Gynecol. 1982; 60(1):1-12 (review). PubMed 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). PubMed 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. PubMed 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. PubMed 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. PubMed 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. PubMed 3389044

Collection Details:

Collection Instructions:

Red-top tube, gel-barrier tube, lavender-top (EDTA) tube, or green-top (heparin) tube.

Transfer the serum into a LabCorp PP transpak frozen purple tube with screw cap (LabCorp N° 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.