Introduction: Central hypothyroidism (CeH) is diagnosed when low thyrotropin (TSH) is associated with a free thyroxine (fT4) below the normal range. Jostel proposed a fT4-adjusted TSH (TSH index: TSHI = log TSH +0.1345 · fT4.), to estimate the degree of pituitary dysfunction (Jostel et al. Clin End 2009).
Methods: Retrospective analysis of patients investigated for pituitary hormone deficiencies (n=276; M:F 166:110) in our centre.
Group A: 120 patients with multiple pituitary hormone deficiencies (MPHD);
A1 (27) remained euthyroid,
A2 (93) had CeH and of these 73 started levothyroxine together or before growth hormone (A2Early) and 14 after growth hormone (A2Late).
Group B: 156 patients with different conditions with increased hypothalamic pituitary dysfunction risk;
B1 (52) had isolated growth hormone deficiency (IGHD).
Results: At diagnosis group A patients had lower TSHI than group B (P<0.01). TSH, fT4 and TSHI were not significantly different between group A1 and B1. At diagnosis no significant difference was found in TSH, FT4 and TSHI between A2Early and A2Late (P 0.608, 0.254, 0.299 respectively). Interestingly TSH and TSHI remained significantly different throughout the followup, between A1 and A2 (P 0.001). fT4 was significantly lower in A2Early compared to A1 (P 0.005) at diagnosis, and, following GH, it decreased in A2Late. GH secretion impacts on thyroid function; however following GH treatment TSH and TSHI did not change significantly within each subgroups (B1 P 0.820 and 0.26; A1 P 0.052 and 0.071; A2Late P 0.54 and 0.37 respectively).
|A1 (Mean)||AGE||TSHI||TSH||FT4||A2 Late (Mean)||AGE||TSHI||TSH||FT4|
|Later/ start TH||6.91±2.31||2.26±0.27||2.49±1.36||14.2±1.14||3.98±2.42||1.65±0.32||2.22±1.11||11.05±1.91|
|Group B||AGE||TSHI||TSH||FT4||Group B1||AGE||TSHI||TSH||FT4|
|Later/ start TH||3.34±4.23||1.95±0.45||10.6616.55||8.97±1.5||7.63±2.09||2.35±0.38||2.79±1.86||14.82±2.11|
Conclusion: Our data suggest that TSHI can be a predictor of CeH, enabling earlier diagnosis of CeH in at-risk patients.
22 - 24 Nov 2017
British Society for Paediatric Endocrinology and Diabetes