Clonidine stimulation test | Right Decisions

Right Decisions
SPEG (Scottish Paediatric Endocrine Group)
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Dynamic function tests for use in paediatric endocrinology
Clonidine stimulation test

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Please get in touch with ann.wales3@nhs.scot with any questions.

Indications for the procedure

Investigation of suspected Growth Hormone (GH) deficiency in childhood (not in adults).

Clonidine is administered orally to provoke GH release.

Preparations for the test

Fast the patient overnight (4h for infants), and measure height and weight.
Calculate surface area from appropriate tables.
Start the test by 09:00h whenever possible.

Drug administration

Drug(s) Given

Clonidine 150 micrograms per m2 body surface area.

Round the dose up to the nearest 25 micrograms.

How Given

Given orally with a small sugar free drink.

Timing of Administration

Give after the two basal blood samples have been taken.

Procedure

Time (minutes)	Action
-30	Insert a reliable cannula. Take venous blood sample.
0	Take venous blood sample. Give oral clonidine dose.
15	Take venous blood sample.
30	Take venous blood sample.
60	Take venous blood sample.
90	Take venous blood sample.
120	Take venous blood sample.
150	Take venous blood sample.

Samples required

(Please view this table in landscape mode on mobile devices)

	Time (minutes)
	-30	0	15	30	60	90	120	150
GH
IGF₁
T₄, TSH

After the test

Once the test is completed, make sure the child has had something to eat and drink.
Side effects of Clonidine (hypotension and drowsiness) may persist for several hours after the test.
Keep the patient lying down for at least an hour after the test.
Check pulse and blood pressure half-hourly and also before allowing the child to get up.
Careful observation of the patient is necessary until late afternoon.

Interpretation

If the plasma GH concentration reaches 6.7 micrograms/L or more, further investigations are not necessary.

If the response is below this level, then an insulin hypoglycaemia test may be necessary.