What Is a Stim Test? A Parent’s Guide to the Growth Hormone Stim Test

Hearing the words “your child may need a stim test” can land like a punch to the gut. Most parents I talk to describe the same spiral: confusion, fear, and a late-night Google search trying to figure out what a “growth stim test” even is.

Take a breath. A growth hormone stim test is a common tool in pediatric endocrinology, and for many families, it’s the step that turns uncertainty into answers and a clear plan.

What is a stim test?

A stim test, short for growth hormone stimulation test, checks whether your child’s body can make enough growth hormone when prompted.

Here is the key reason it exists. Growth hormone is released in pulses, not continuously throughout the day. So a single random blood draw can look “low” even in a healthy child, which makes it a poor stand-alone test for diagnosing growth hormone deficiency.

Instead, stim testing uses medications that gently stimulate the pituitary gland, with timed blood draws over several hours, to see how much growth hormone your child’s body can release.

Why doctors order a growth hormone stim test

A pediatric endocrinologist usually considers a growth hormone stim test when a child’s growth pattern suggests something more than being naturally small.

Common reasons include:

  • Short stature compared with peers and family expectations
  • Slow growth velocity (growing fewer inches per year than expected)
  • Crossing down percentiles on the growth chart over time
  • Clues that help your provider sort out a constitutional delay (a “late bloomer”) versus possible growth hormone deficiency

A stim test does not replace the full growth evaluation. It is one piece of the puzzle, alongside growth charts, history, exam, labs, and often a bone age x-ray.

What happens during a stim test, step by step

Every clinic has its own protocol, but most stim testing days follow a similar flow.

Before the test

  • Fasting: You will usually be asked not to give your child food the morning of the test (your team will give exact instructions).
  • Plan for comfort: Bring a tablet, headphones, favorite movies, a blanket, or a stuffed animal.

During the growth hormone stim test

  • An IV is placed in the hand or arm. This is the part most kids dislike the most.
  • Medications are given through the IV (or sometimes by mouth, depending on the protocol) to encourage growth hormone release.
  • Timed blood draws happen over the next few hours, usually through the same IV, so your child is not being stuck repeatedly.
  • Total time: Many tests run about 2½ to 6 hours (varies by protocol and facility).

Most kids spend the test resting, watching movies, dozing, or just hanging out with you nearby.

Is a growth hormone stim test safe?

For most children, a growth hormone stimulation test is safe, and clinics closely monitor the entire time.

That said, the medications used can cause temporary side effects, which is why your child’s vital signs and symptoms are watched carefully during the test.

Common side effects can include:

  • Low blood sugar (which can feel like shakiness, lightheadedness, nausea, or sweating)
  • Sleepiness or fatigue
  • Lower blood pressure with certain protocols or medications
  • Nausea or vomiting
  • Headache or flushing

If side effects happen, they are usually manageable, and most kids feel back to normal later that day.

How long do stim test results take?

This is one of the most frustrating parts for families.

In many hospital systems, getting the test scheduled can take months, and then the results and follow-up plan can add more waiting.

At The Endocrine Company, our goal is to remove the “lost time” piece. Most families can complete bone age imaging, stim test, and a results visit in about a week, so you are not stuck wondering what is happening while your child’s growth window keeps moving forward.

What the results can mean for your child

Your provider will interpret results alongside your child’s full growth picture, not in isolation. In general, results tend to land in one of these buckets:

If the result is normal

This can be incredibly reassuring. Your child may still need monitoring, but a normal response often points away from true growth hormone deficiency and toward other explanations for short stature or slow growth.

If the result is abnormal

An abnormal growth hormone stim test can support a diagnosis of growth hormone deficiency (or another treatable growth hormone-related issue), which may open the door to treatment options.

Timing matters. For children with growth hormone deficiency, earlier treatment is associated with a higher likelihood of reaching near-normal adult height. Your care team will also consider factors such as bone age and whether the growth plates are still open when discussing expected outcomes.

You don’t have to navigate stim testing alone

If you are here because you are asking, “What is a stim test?” you are not behind. You are doing what good parents do. You are trying to understand, so you can make calm, confident decisions for your child.

When you are ready, we can walk you through the next step and help you move from questions to answers, without months on a waitlist.

Next step: Schedule a growth evaluation

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