In a Dutch study of people with well‑treated Hashimoto's thyroiditis, researchers used a GHRP‑6 test to see how many also had growth‑hormone deficiency. Only 2 out of 515 (0.4%) actually had a deficiency, even though about 10% showed low IGF‑I levels.

Autoimmune hypophysitis can result in GH deficiency (GHD) and is associated with other autoimmune endocrine diseases like Hashimoto's thyroiditis. Recent studies suggest a high prevalence (5%) of GHD in Hashimoto's thyroiditis. Our objective was to establish the prevalence of GHD in patients with treated autoimmune hypothyroidism (AIH). We included patients with spontaneous AIH [thyroid peroxidase antibodies (TPO-Ab) >or=100 kU/liter], who were adequately treated with T(4) (TSH 0.2-5.0 mU/liter). Exclusion criteria were previous I(131) treatment, thyroid surgery, or a history of hypothalamic or pituitary disease. Patients were recruited via our outpatient clinics and via patient self-help organizations. We measured serum TSH, free T(4), TPO-Ab, and IGF-I. If the IGF-I concentration was below the 10th percentile of age-specific reference values, a GHRH/GH-releasing peptide (GHRP)-6 test was done. GHD was defined as a GH peak after GHRH/GHRP-6 below the 2.5th percentile of age-specific reference values. IGF-I concentration and GH peak after GHRH/GHRP-6 test were measured. From 860 patients who applied, 322 did not satisfy inclusion criteria (157 because TPO-Ab was <100 kU/liter, 165 because TSH was <0.2 or >5.0 mU/liter), and 23 had an exclusion criterion. In the remaining study population of 515 patients (476 female, 39 male), 49 patients (9.5%) had an IGF-I concentration below the 10th percentile. These patients underwent a GHRH/GHRP-6 test. Two patients had a GH peak below the 2.5th percentile. The prevalence of GHD in Dutch patients with AIH is 0.4% (two of 515).