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Epic Test Code LAB2428 Growth Hormone Supression Test

Performing Location(s)

BMC

Specimen Type

Serum or Plasma(Glucose Only)

Preferred Container

Gold or Red top tube

Alternate Container

Green top tube (glucose only)

Minimum Volume to Submit for Testing

0.5 mL Serum or Plasma for Glucose

0.5 mL Serum for Growth Hormone Supression Test

Storage Requirements

Sample tubes should be centrifuged within 2 hour of collection followed by transfer of the serum (red or gold top) or plasma (green top) to a labeled plastic, aliquot tube.
See Causes of Rejection for temperature requirements.

Transportation Needs

Deliver specimen to laboratory within 1 hour of collection if unspun. If not possible see "storage Requirements". 

Causes for Rejection

Mislabeled or unlabeled specimen
Less than 50% draw for Vacutainer tubes
Serum stored on clot more than 4 hours
 >3 days refrigerated
>  8 hours room temperature
> 5 days Frozen
Hemolysis > 500 mg/dL HgB
Lipemia > 700 mg/dL Trig
Bilirubin > 40 mg/dL Bili
Patient not fasting prior to start of GTGH, stressed patient (surgery, infection, corticosteroids)Specimen not labeled with hourly times
Blood stored on clot for more than 4 hours, gross hemolysis

Reference Values

Diagnosis of Diabetes and Pre-diabetes (2GTT)
(75 gram dose)

Two or more glucose concentrations must exceed the reference range
Specimen Normal Reference Range (mg/dL) Pre-Diabetes Diabetes
Fasting 70-100 110 - 125 > 126
2 hour 95 - 130 140 - 199 > 200

 

Diagnosis criteria for 3 Hr GTT (3GTTL) (100 gram dose)

Two or more glucose concentrations must exceed the reference range

Specimen Normal Reference Range (mg/dL)
Fasting 70-100
1 hour 105 - 160 
2 hour 95 - 130 
3 hour 70 - 110

 

Glucose Tolerance Tests for OB patients

(2011 ACOG Clinical Practice Recommendations)

 

Diagnosis of Gestational Diabetes (OBGTT)
(75 gram dose)

Two or more glucose concentrations must exceed the reference range
Specimen Normal Reference Range (mg/dL) High Critical Value Low Critical Value
Fasting 70-95 > 450 < 40
1 hour 96 -179 > 450 < 40
2 hour 100-152 > 450 < 40
Growth Hormone, Adult Reference Range
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.
Fasting Glucose Reference Ranges
(2012 ADA Clinical Practice Recommendations)
Age Interpretation Value High Critical Value Low Critical Value
> 1 week Normal Fasting 70-100   <45
≤1 week   Normal Fasting 45-99 >450 <45

Available STAT

No

Days of Analysis

M-F

Additional Information

Must preschedule an appointment in the endocrinology Clinic at 607-547-3273.   

Patient Preparation:
Patient Instructions for Fasting Laboratory Testing

Test is performed at Bassett Medical Center in Endocrinology Patients having oral glucola need to be monitored by an RN/LPN. Proper preparation of the patient prior to the test also needs to be addressed by the ordering Practitioner  and a nurse. The ordering Practitioner is responsible for monitoring the patient during the test.

Patient should be NPO after midnight the night before the test.
Patient should be active and have adequate food intake with at least adequate carbohydrates (at least 150 g. carbohydrate daily) for 3 days prior and then fast 8 hours prior to test.
Many drugs interfere. They include steroids, oral contraceptives, diuretics, and antihypertensive drugs including thiazides, furosemide, anticonvulsants, psychoactive drugs, antituberculous agents, and anti-inflammatory drugs including salicylates.
Patient should not be stressed (e.g. following surgery, with infections or on corticosteroids)

Requisitioning/Labeling Requirements:

When requesting

1. Enter the code LAB2428. When order is released it will expand out into the appropriate number of specimens for the tolerance selected.

2. Specimen labels will print SPECIFIC FOR EACH SPECIMEN IN THE TEST. Be sure to use the correct specimen label for each test and each timed collection.

 

LINKS:Limitations of Procedure / Contraindications, Reference Range

Includes

Fasting blood glucose and growth hormone followed by glucose and growth hormone levels drawn at timed intervals after administration of a glucose load (see chart)

 

LIS Test Code Epic Name Usage Consists of
LAB525 Growth Hormone Supression Test suspicion of Acromegaly Fasting, 1/2 hr, 1 hr, 1 1/2 hr, 2 hr Growth Hormone
LAB82 Glucose   Fasting, 1/2 hr, 1 hr, 1 1/2 hr, 2 hr Glucose

 

Methodology

see individual tests GLUC and GH

CPT Code

see GLUC and GH

Last Updated

18-Mar-22 BHD