This document outlines several provocative tests used to evaluate growth hormone levels, including: 1) The glucose suppression test which measures GH levels after glucose administration, with normal individuals showing suppression and acromegaly patients failing to suppress. 2) Exercise and insulin-induced hypoglycemia stimulation tests which trigger GH increases through physical exertion or controlled hypoglycemia. 3) Arginine stimulation involves infusing arginine to inhibit somatostatin and stimulate GH release. 4) Interpretation of results depends on assay sensitivity and stimuli used, with normal responses above 7-10 μg/L and confirmation needed for subnormal results. Precise procedures, interpretations, and contraindications are provided for each test

1. D R . G H U L A M M U R T A Z A
R E S I D E N T C H E M I C A L P A T H O L O G Y
D . I . M . C
Provocative test for Growth
Hormones

2. Out lines
 Glucose Suppression of Growth Hormones Test
 Exercise stimulation test for Growth Hormones
 Insulin Induced Hypoglycemia Stimulation Test
 Arginine Stimulation Test for Growth Hormones

3. Interpretation of GH Stimulation test :
 Totally depends on assay specificity & sensitivity &
stimulus provided
 If response is normal no need of further test advised
 A subnormal response from a single provocative test
is not a diagnostic for GH & should be confirmed
with a second provocative test .

4. Glucose Suppression of Growth Hormones Test
 Rationale :
 Normal subject shows suppression of serum growth
hormones concentration after oral administration of
glucose.
 Subjects with acromegaly fails to exhibit appropriate
GH suppression

5. Procedure
 Over night fasting required
 Collect a base line sample for Glucose & GH
 A solution of 75g of glucose is given orally in children
( 1.75g/kg ) to a maximum dose of 75 g)
 Glucose & GH are measured again on specimen
collected 30,60,90 & 120 minutes

6. Interpretation
 Normal individuals shows 1-2 µg/L.
 Patient with liver disease ,Uremia ,& heroin
addiction shows False Positive results
 Acromegaly shows Paradoxical increase in GH conc:

7. Exercise induced stimulation test for Growth
hormones
Rationale :
brisk exercise normally cause an increase in serum growth
hormone concentration
Procedure :
best performed during morning after over night fast
but can be done at any time .
Vigorous physical exercise ( running on treadmill) is
performed for 20 minutes .

8. A venous blood sample is collected for
determination for GH
A second sample may also be obtained 40minutes
after exercise in case of delayed GH release
Interpretation :
serum GH concentration is 7 to 10 µg/L or greater .
Normal response in adult is 5µ/L .

9. L-DOPA Induced GH stimulation test
 L-Dopa (Levodopa ) stimulates the release of GH .
 It is administrated orally ( tab Sinemet 250mg ) at a
dose of 500mg in adults & 10mg/kg in children
< 15kg 125mg
16-35 kg 250mg
>35mg/kg 500mg

10.  Collect GH sample at 0,30,60,90 & 120 minutes
 Side effect : nausea ,vomiting & headache
 Interpretation:
normal response >7ng/ml (>7.5 ng/ml )

11. Insulin induced hypoglycemia stimulation test
Pituitary
Growth
Hormones
Directly
Measured
ACTH
CORTISOL
( indication of
ACTH response
Considered as
definitive & gold
standard test

12. Preparation : Procedure
1. Overnight fasting
(8-10 hours)
2. Child ( 4 hours )
3. An indwelling I/V line is inserted
4. Ensure that 25 % dextrose &
hydrocortisone available for I/v
injection if necessary
5. A glucose drink must be available
this may be – 40g dextrose powder
dissolved in half glass of water
6. Inj glucagon should be available in
case i/v access is lost
 Written consent
 Explain procedure in detail including
symptoms of hypoglycemia
 Forms to documents the time & value
of results
 Arrange a glucometer
 The physician must be present
throughout the test
 Regular Insulin dose is 0.1 u/kg
( 0.1u/kg to 0.15 u/kg )
Insulin induced hypoglycemia stimulation test

13.  Collect the sample at baseline 0 ,10 ,20 ,± 30 ,40, 60
for GH , Glucose & cortisol ±75, ±90, & ±120
 Glucose level should also be followed using bedside
glucose monitoring
 Adequate pituitary stimulation is evident when
patient becomes symptomatic ( sweating & tremors )
 When glucose level falls below 40-45mg/dl.

14.  Additional insulin can be administrated if these
criteria are not met within 30 minutes
 If the glucose level again fails to drop the desired
level on second time ,the procedure should be
withdraw
 Post test monitor for one hour in ward then
discharge

15. Contraindication
 Patient with epilepsy & seizure disorder
 Age > 60 years
 Ischemic heart disease
 Cardiovascular insufficiency
 Hypothyroidism(impair the GH & cortisol response )
 Sever panhypopituitarism

16. Interpretation
 Normal response should be 7 to 10 µg/L
 No response or inadequate response may be due to
pituitary hormone deficiency or hypothalamic lesion
.
 Serum cortisol response conc: should increase to a
peak value of 18-20 µg/d L ( 497- 552 nmol/L ) .

17. GHRH & Arginine induced GH stimulation
 Second line test for GH deficiency in adults
 Strong stimulus for GH production as two agent are
co administrated
 A suitable alternate to ITT
 Arginine inhibits Somatostatin release
 GHRH induced GH –release

18. GHRH & Arginine induced GH stimulation
Intra venous infusion of
arginine (o.5/kg) together
with i/v bolus of GHRH
1mcg/kg is administered
Serum samples for GH are
obtained baseline & every
15-30 minutes for two
hours (0,30,60,90,120 )
Important to distinguished
hypothalamic related cause
of GH deficiency

19. Arginine stimulation test for growth hormone
 Over night fasting
 10% solution of arginine hydrochloride is infused over 30
minutes in dilute form 1;2 if weight is < 15kg or 1;3 if > 15kg
 0.5g/kg body weight ( maximum dose 30g )
 Blood samples are taken 0,30,60 & 90 after infusion
 Optimal time points are ±15 & ± 120 minutes
 Result :
normal peak GH > 7-10 nm/ml or greater .
 Contra indicated in renal or liver disease
exercise can be added to potentiate the response

20. Clonidine induced GH stimulation test
 Clonidine is centrally acting ,stimulate alpha receptors
 Clonidine is administered at dose of 0.15 mg/m2
 Collect GH sample at base line 0, 30,60 & 90
 Normal peak of GH > 7.5 ng/ml
 S/E side effect is hypotension
< 13kg 0.05mg
> 13kg 0.1 mg (0.1mg/tab

21. Thank
you

22. References
 Tietz book of Clinical chemistry 6th edition
 Dr.Sahar Iqbal Presentation (CPSP CME).