Endocrine Abstracts

Introduction: TSHOMAs are rare pituitary tumors with prevalence of 1–2 cases per million. We present a case of of TSHoma where the course was complicated by the coexistence of autoimmune hypothyroidism.

Case: 41 year old male presented with fatigue, lethargy and palpitations. On screening was found to have raised t3 – 216.30 ng/dl (N-70-204 ng/dl), t4 – 12.10 μg/dl(N-4.2-11.6 μg/dl) and TSH – 27.55 uIU/ml (0.2–5.7 uIU/ml). Further evaluation revealed raised free t3 (FT3), free t4 (FT4) and TSH (column 1, Table 1), raised anti thyroid peroxidase antibodies and negative TSH receptor antibody, normal cortisol – 10.8 μg/dl (N-5-25), testosterone – 769.73 ng/dl (N-275-900), prolactin – 18.89 ng/ml (5–25), IGF1 – 124 ng/ml (64–210) levels. Thyroid function of first degree relations was normal. SHBG – 78.20 nmol/l (N-11.2-78.1) and alpha subunit levels – 3.8 ng/ml (0.1–0.5) were raised. TSH concentration significantly reduced 5 hours after single octride dose as well as after three doses of 100 μg octride over 24 h. MRI confirmed presence of pituitary macroadenoma 2.4×1.2×1.2 cm abutting the chiasma (visual fields normal). Patient was subjected to transsphenoidal surgery. The adenoma immunostained positive for TSH, was also positive for p53 with MIB index 3–5%. Patient FT3, FT4 and TSH was low 2 weeks post surgery and 25 μg thyroxine was started. Follow up report at 6 weeks showed low FT3, FT4 and raised TSH levels after which thyroxine was stepped up. Patient did not need any other hormone replacement.