Prevalence of growth hormone deficiency in autoimmune hypothyroidism
Silvia Eskes, Erik Endert, Eric Fliers & Wilmar Wiersinga
Background: Autoimmune hypophysitis can result in growth hormone deficiency (GHD). Although autoimmune hypophysitis is uncommon, it is associated with other autoimmune endocrine diseases like autoimmune hypothyroidism (AIH). Recent studies suggest a high prevalence (5%) of GHD in AIH, which could contribute to the reduced quality of life frequently observed in patients with AIH despite adequate treatment with thyroxine.
Objective: To establish the prevalence of growth hormone deficiency in patients with AIH.
Patients: We included patients with AIH (TPO-Ab≥100 kU/l), who were adequately treated with thyroid hormone suppletion (TSH 0.25.0 mU/l). Exclusion criteria were prior I131 treatment, thyroid surgery, or a history of hypothalamic or pituitary disease. Patients were recruited via our outpatient clinics and via patient self-help organizations. Eight hundred and thirty-seven patients applied for the study.
Research design and methods: We measured TSH, FT4, TPO-Ab and IGF-I. If the IGF-I concentration was <10th percentile of age specific reference values, a GHRH/GHRP-6 test was done. GHD was defined as a growth hormone peak after GHRH/GHRP-6 below the 2.5th percentile according to age specific reference values.
Results: In total 837 patients applied for the study, 515 (476 female, 39 male) were included. Three hundred and twenty-two were not included (157 because TPO-Ab<100 kU/l, 165 had TSH<0.2 or >5.0 mU/l).The IGF-I concentration was <10th percentile in 49 of 515 patients. These 49 underwent a GHRH/GHRP-6 test. Two had a growth hormone peak <2.5th percentile.
Conclusion: The prevalence of GHD in Dutch patients with AIH is 0.4% (2 out of 515 patients).