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Epic Test Code LAB525 Growth Hormone, Serum

Additional Codes

MML Code: HGH

LIS Code: GH

NY State Approved

Yes

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Reporting Name

Growth Hormone, S

Method Name

Immunoenzymatic Assay

Specimen Stability Information

Specimen Type Temperature Time
Serum Refrigerated (preferred) 7 days
  Frozen  90 days


Specimen Required


Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Specimen Volume: 0.6 mL

Collection Instructions:

1. Fasting

2. If multiple specimens are drawn, submit each vial under a separate order.

3. Label specimens appropriately (corresponding draw time).


Specimen Type

Serum

Specimen Minimum Volume

0.5 mL

Reference Values

Adults

Males: 0.01-0.97 ng/mL

Females: 0.01-3.61 ng/mL

Reference intervals have not been formally verified in-house for pediatric and adolescent patients. The published literature indicates that reference intervals for adult, pediatric, and adolescent patients are comparable.

 

For SI unit Reference Values, see https://www.mayocliniclabs.com/order-tests/si-unit-conversion.html

Analytic Time

1 day

Day(s) and Time(s) Performed

Monday through Friday 5 a.m. – 12 a.m., Saturday 6 a.m. – 6 p.m.

CPT Code Information

83003

Reject Due To

Hemolysis

Mild OK; Gross reject

Lipemia

Mild OK; Gross OK

Icterus

NA

Other

NA

Cautions

The test has limited value in assessing growth hormone secretion in normal children. IGF1I / Insulin-Like Growth Factor 1, Serum is recommended as the first test for assessing deficient or excess growth during childhood and adolescent development; reference intervals for Tanner stages are available. Suspected causes of dwarfism need to be diagnosed with the aid of provocative testing.

 

This test is not useful as a screen for acromegaly; IGF1 / Insulin-Like Growth Factor 1, Serum is preferred. Elevated levels of human growth hormone indicate the possibility of gigantism or acromegaly, but must be confirmed with stimulation and suppression testing.

 

Growth hormone is secreted in surges; single measurements are of limited diagnostic value.

Interpretation

Acromegaly: For suppression testing, normal subjects have a nadir growth hormone (GH) concentration of <0.3 ng/mL after ingestion of a 75-gram glucose dose. Patients with acromegaly fail to show normal suppression. Using the Access ultrasensitive hGH assay, a cutoff of 0.53 ng/mL for nadir GH was found to most accurately differentiate patients with acromegaly in remission from active disease with a sensitivity of 97% (95% CI, 83%-100%) and a specificity of 100% (95% CI, 82%-100%).(1)

 

Deficiency: A normal response following stimulation tests is a peak GH concentration >5 ng/mL in children and >4 ng/mL in adults. For children, some experts consider GH values between 5 ng/mL and 8 ng/mL equivocal and only GH peak values >8 ng/mL as truly normal. Low levels, particularly under stimulation, indicate human growth hormone deficiency.

Specimen Retention Time

14 days

Useful For

Diagnosis of acromegaly and assessment of treatment efficacy (in conjunction with glucose suppression test)

 

Diagnosis of human growth hormone deficiency (in conjunction with growth hormone stimulation test)

Clinical Information

The anterior pituitary secretes human growth hormone (hGH) in response to exercise, deep sleep, hypoglycemia, and protein ingestion. hGH stimulates hepatic insulin-like growth factor-1 and mobilizes fatty acids from fat deposits to the liver. Hyposecretion of hGH causes dwarfism in children. Hypersecretion causes gigantism in children or acromegaly in adults.

 

Because hGH levels in normal and diseased populations overlap, hGH suppression and stimulation tests are needed to evaluate conditions of hGH excess and deficiency; random hGH levels are inadequate.