The HP short DST test, also known as the ACTH stimulation test, is a medical test that assesses adrenal gland function. It involves measuring cortisol levels before and after administration of synthetic ACTH hormone. ACTH stands for adrenocorticotropic hormone, which stimulates the adrenal glands to produce cortisol. The test helps diagnose adrenal insufficiency or Addison’s disease.
What is the purpose of HP short DST test?
The main purposes of the HP short DST test are:
Diagnose adrenal insufficiency
Adrenal insufficiency, also called Addison’s disease, occurs when the adrenal glands do not produce enough cortisol. This test helps confirm adrenal insufficiency by checking whether the adrenal glands respond normally to ACTH stimulation. Inadequate cortisol response indicates impaired adrenal function.
Identify cause of adrenal insufficiency
The test helps determine if adrenal insufficiency is due to a problem with the adrenal glands themselves (primary adrenal insufficiency) or due to inadequate ACTH production from the pituitary gland (secondary adrenal insufficiency). Normal ACTH levels with impaired cortisol response indicate primary adrenal failure.
Monitor steroid replacement therapy
For people receiving corticosteroid replacement therapy for adrenal insufficiency, the HP DST can help determine if the dose is adequate. Optimal dosing restores normal adrenal responsiveness on the test.
Assess recovery of adrenal function
The test may be performed periodically after treatment for adrenal impairment to assess whether adrenal function has recovered. Return of normal cortisol response on the test indicates the adrenal glands have regained function.
When is HP short DST test ordered?
Doctors may order an HP DST when adrenal insufficiency is suspected based on symptoms and other findings. Symptoms of adrenal insufficiency include:
– Fatigue
– Muscle weakness
– Loss of appetite
– Weight loss
– Abdominal pain
– Diarrhea
– Nausea/vomiting
– Low blood pressure
– Salt craving
– Skin changes
The test is often ordered when blood tests show low cortisol levels or an impaired response to physiological stress. It can help determine if medication such as prednisone is required. Repeat testing may be performed after treatment to reassess adrenal function.
How does the HP short DST work?
The test involves measuring cortisol levels in the blood before and after an injection of synthetic ACTH hormone. This standardized ACTH dose stimulates maximal cortisol secretion from functioning adrenal tissue.
Here are the main steps:
1. Baseline cortisol measurement
A blood sample is drawn to measure the patient’s baseline cortisol level in the morning after fasting and while resting.
2. ACTH administration
Synthetic ACTH is injected intravenously or intramuscularly. Common dosing is 250 mcg for adults.
3. Second cortisol measurement
A second blood sample is drawn 30-60 minutes after the ACTH injection to measure the stimulated cortisol level.
4. Interpretation
– Normal response: Cortisol increases by > 7-10 μg/dL indicates normally functioning adrenal glands.
– Impaired response: Lack of adequate cortisol increase suggests adrenal insufficiency. Different cutoffs are used at testing labs.
– Indeterminate response: Borderline cortisol response may require repeat testing.
Preparation for the HP short DST
Proper preparation is important for reliable test results. Guidelines include:
– Morning test timing – Cortisol production follows a daily circadian rhythm and is highest in the morning, so the test should be done in the AM.
– Fasting for 8-12 hours before the test.
– No strenuous exercise the day before the test. Activity can temporarily increase cortisol.
– Hold off drugs that influence cortisol levels. Your doctor may advise stopping oral estrogens, androgens, mineralocorticoids, and other cortisol-altering medications in the days leading up to the test.
– Discuss any recent or long-term corticosteroid use with your doctor as this can impact results.
Let your doctor know if you are ill, hospitalized, or under significant physical or mental stress at the time of testing as these can also affect cortisol levels.
During the HP short DST procedure
Plan to be at the hospital or testing facility for 1-2 hours. Here’s what to expect:
Admission
You will be asked to provide a medical history, list current medications, and describe any symptoms. Your weight and vitals may be recorded.
Baseline blood draw
A small sample of blood will be collected from a vein in your arm to measure your baseline cortisol level.
ACTH injection
The synthetic ACTH will be injected into your vein or muscle tissue. You may experience brief redness or swelling at the injection site.
Wait period
You will wait 30-60 minutes for the ACTH to stimulate your adrenal glands. You can relax during this time.
Second blood sample
A second blood sample will be taken to measure your stimulated cortisol level.
Completion
A bandage will be applied to the blood draw site. You are free to leave once the procedure is complete.
After the HP short DST
You can resume normal activities immediately after the test. Side effects are uncommon but may include:
– Dizziness
– Flushing
– Headache
– Nausea
Call your doctor if you experience concerning symptoms after the test. It may take a few days for your cortisol levels to return to baseline.
Avoid strenuous exercise and alcohol intake for 24 hours after the test. Drink plenty of fluids and eat normally.
Your doctor will share the test results and discuss treatment options at a follow-up appointment if adrenal impairment is found.
HP short DST results interpretation
Interpreting the stimulated cortisol response helps diagnose adrenal function. Reference ranges vary slightly between labs.
Normal response
A normal stimulated cortisol level is ≥ 18-20 μg/dL. This indicates properly functioning adrenal glands responsive to ACTH.
Impaired response
Lack of adequate cortisol rise (change from baseline < 7-10 μg/dL) suggests adrenal insufficiency. The lower the stimulated level, the more severe the adrenal impairment.
Indeterminate response
Borderline stimulated cortisol between 10-18 μg/dL may warrant repeat testing for clarification.
ACTH and electrolyte levels provide additional information on the cause of adrenal impairment. Your doctor will interpret the results in context of your symptoms and health history.
Conditions diagnosed with HP short DST
Abnormal test results can help identify various adrenal disorders:
Primary adrenal insufficiency
Damage to the adrenal glands reduces cortisol production. Causes include autoimmune Addison’s disease, infections like tuberculosis, adrenal hemorrhage, and medications.
Secondary adrenal insufficiency
This arises from inadequate ACTH secretion by the pituitary gland due to tumours, inflammation, or head trauma. Cortisol response is impaired while ACTH is low.
Congenital adrenal hyperplasia (CAH)
Genetic defects in cortisol synthesis enzymes lead to impaired cortisol response on the test. Electrolyte imbalances are also seen.
Adrenal tumours
Cortisol overproduction from benign or cancerous adrenal tumours can suppress normal glands. This results in a diminished HP DST response.
Advantages and limitations
Advantages
– Helps definitively diagnose adrenal insufficiency
– Assesses adrenal reserve and function
– Determines cause (primary vs secondary)
– Monitors steroid replacement therapy
Limitations
– Does not identify specific underlying cause
– Borderline results may require repeat testing
– Other factors (stress, medication use) can affect results
– Not accurate in critically ill patients
Overall, when performed correctly, the HP short DST provides valuable information about adrenal function that guides appropriate treatment.
Conclusion
The HP short DST is an important diagnostic test for adrenal impairment. It checks adrenal responsiveness to ACTH stimulation by measuring cortisol levels before and after synthetic ACTH administration. Diminished cortisol response indicates adrenal insufficiency and helps guide treatment with corticosteroid medications if needed. When interpreted in clinical context, the HP short DST provides vital information about the functional status of the adrenal glands.
