Growth hormone testing

Growth hormone testing assesses how well the pituitary gland produces growth hormone, using either dynamic stimulation tests or, in specific situations, measurement of related markers such as IGF-1. It is used to investigate suspected growth hormone deficiency or, less commonly, excess. Because growth hormone levels naturally fluctuate throughout the day, a single random blood test is rarely sufficient on its own.

Testing may be recommended for children with unexplained slow growth, or adults with symptoms suggestive of deficiency such as low energy, changes in body composition, or a relevant pituitary history. It can also be used to investigate suspected growth hormone excess, which can cause conditions like acromegaly. Your doctor will decide on the right testing approach based on your specific symptoms and history.

Testing often involves a dynamic stimulation test, where a substance is given to trigger growth hormone release, followed by blood samples taken at set time intervals to see how the pituitary responds. An IGF-1 blood test, which reflects overall growth hormone activity over time, is often used as an initial screening test. These tests are usually performed in a hospital or specialist clinic setting under medical supervision.

Yes, growth hormone stimulation testing is generally safe and well tolerated, though it can cause temporary side effects such as nausea or flushing depending on the specific test used. It is performed under medical supervision to monitor for and manage any side effects. Serious complications are rare.

Dynamic stimulation testing is considered the most reliable way to diagnose growth hormone deficiency, since a single random blood level is not accurate due to natural fluctuation throughout the day. Results are interpreted alongside clinical symptoms and sometimes additional pituitary imaging. An experienced endocrinologist ensures the results are interpreted correctly in the context of your overall clinical picture.

If testing confirms deficiency, treatment with growth hormone replacement may be discussed, tailored to your age and clinical situation. If excess growth hormone is found, further investigation, such as pituitary imaging, is arranged to look for an underlying cause like a pituitary tumour. Your endocrinologist will explain the results and any recommended next steps in detail.

The principles are similar, using stimulation tests and IGF-1 measurement, but the clinical context differs: in children, testing usually investigates poor growth, while in adults it typically investigates symptoms of deficiency related to a known pituitary condition or history. Reference ranges and interpretation also differ between children and adults, reflecting normal developmental changes in growth hormone levels. A paediatric or adult endocrinologist, as appropriate, will guide testing and interpretation.

Preparation usually involves fasting for a period before the test and sometimes avoiding certain medications, as instructed by the testing clinic. Clear instructions are usually given in advance, since preparation requirements can vary depending on the specific test used. Following these instructions carefully helps ensure accurate results and avoids the need to repeat testing.

Ask your doctor about growth hormone testing if you have symptoms or a history suggestive of deficiency or excess, such as unexplained fatigue and body composition changes, or features suggestive of acromegaly like enlarging hands, feet, or facial features. A private endocrinology referral for appropriate testing can typically be arranged within about two weeks. Because interpretation can be complex, testing and result review are best done under specialist endocrinology guidance.