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Alpha-Subunit Pituitary Tumor Marker, Serum

Test ID: AGPS

Test

Method

Immunochemiluminescent Assay

Report Includes

α-Glycoprotein Subunit

Specimens

Avoid gel-separator tubes; Serum

Clinical Utility

Adjunct in the diagnosis of pituitary tumors
As part of the follow-up of treated pituitary tumor patients
Differential diagnosis of thyrotropin-secreting pituitary tumor versus thyroid hormone resistance
Differential diagnosis of constitutional delay of puberty versus hypogonadotrophic hypogonadism

Test Location

MN, USA

Test Version

12-Oct-2021

Specimen

Specimens

Avoid gel-separator tubes; Serum

Sample Volume

1 mL

Minimum Volume

0.35 mL

Specimen Comment

Avoid gel-separator tubes.
This test should not be ordered on pregnant patients.

Stability

Refrigerated 7 days
Frozen 90 days

Rejection Criteria

Hemolysis Gross
Other Gel-separator tube

Test Version

12-Oct-2021

Performance / Interpretation

Method

Immunochemiluminescent Assay

Turnaround Time

7 days

Specimen Retention Time

90 days

Results

Name Units Reference Range Conversion Factor
α-Glycoprotein Subunit ng/mL
  • Pediatric Reference Ranges
  • 0 - 5 d: ≤50
  • 6 days - 12 w: ≤10
  • 3 m - 17 y: ≤1.2
  • Tanner Stage II - IV*: ≤1.2
  • Adult Reference Ranges
  • Males: ≤0.5
  • Female Premenopausal: ≤1.2
  • Female Postmenopausal: ≤1.8
Pediatric and adult reference values based on Mayo studies.
*Puberty onset (transition from Tanner stage I to Tanner stage II) occurs for boys at a median age of 11.5 (+/-2) years and for girls at a median age of 10.5 (+/-2) years. There is evidence that it may occur up to 1 year earlier in obese girls and in African American girls. For boys, there is no proven relationship between puberty onset and body weight or ethnic origin. Progression through Tanner stages is variable. Tanner stage V (adult) should be reached by age 18.
CAUTIONS
False-positive elevations in serum free alpha-subunit levels may be seen in some women if blood specimens are drawn within 24 hours of ovulation.
Patients with end-stage renal failure may have serum free alpha-subunit concentrations of up to 6-times the upper limit of reference range.
Elevated alpha-subunit results on patients with elevated thyrotropin (TSH) should be interpreted with caution due to TSH cross-reactivity with the assay.
Assisted reproduction involving ovarian hyperstimulation or in vitro fertilization may be associated with the elevation in serum free alpha-subunit levels.
Pregnancy is associated with very substantial, physiological elevations in serum free alpha-subunit levels, paralleling chorionic gonadotropin (hCG) secretion. This test should not be ordered on pregnant patients.

Test Location

MN, USA

Test Version

12-Oct-2021

Interface / Setup

Test Version

12-Oct-2021