We are grateful for your letter and agree that it is vital to avoid unnecessary additional testing in children. The basic investigation scheme in our article is based on published consensus guidance.1,2 This panel of tests was recommended as a screen to identify conditions that could potentially be managed in primary care (avoiding unnecessary referral) and/or to direct referrals appropriately. More ‘specialised’ tests included in the baseline assessment (but not in the article as they may not be universally available or difficult to interpret) are karyotype in short girls to exclude Turner syndrome and serum insulin-like growth factor-I (IGF-I) as a marker of growth hormone (GH) secretion.
It is vital to exclude Turner syndrome in short girls as it has an incidence of I:2000, short stature is present in 98% of Turner syndrome individuals, and is the most common presenting feature in childhood. If karyotype is not available, follicle-stimulating hormone (FSH) at ages <2 and >9 years may be helpful as this could identify primary ovarian failure, another common finding in Turner syndrome.
A random or ‘baseline’ growth hormone (GH) level is not merited as GH is secreted in a pulsatile manner. GH deficiency (GHD) is formally excluded by provocation testing only undertaken in specialist centres equipped to undertake endocrine dynamic testing. Serum IGF-I is a marker of GH action and can be helpful. However, it is usually a secondary-level investigation, as interpretation can be challenging, particularly if there are associated nutritional issues.
Additionally, more moderate GHD can be associated with normal IGF-I values. Therefore, an IGF-I level within the normal range does not necessarily exclude GHD and this needs to be carefully considered when there is a high clinical suspicion of GHD.
- © British Journal of General Practice 2023