Clinical Case: A 51 year old woman of south Asian descent was referred by her GP to outpatient endocrine clinic for assistance with her mixed hyperlipidaemia (Cholesterol 9.5 mmol/L, HDL Cholesterol 1.03 mmol/L Triglycerides 6.7 mmol/L). Her past medical history included a previous hemithyroidectomy for removal of a thyroid nodule (histologically benign) and obesity.
The patients symptoms were of weight gain (5 kg in 18 months), mild lethargy and widespread aches and pains.
The patient was found to have a persistently elevated Creatine Kinase (995 1950 Ui/L [24 170]) with a normal autoimmune screen.
Serial TSHs since the hemithyroidectomy had been within reference range (2.17 to 3.26 mUi/L [0.4 4.5]). However, when thyroid hormones were measured directly the patient was found to be profoundly hypothyroid (Free T4 1.7 pmol/L [12.3 ? 20.2], Free T3 1.3 pmol/L [3.7 6.7]).
Further work-up was suggestive of combined anterior pituitary hormone deficiency (09:00 Cortisol 195 nmol/L, IGF-1 2.4 nmol/L, Prolactin 9 mU/L, FSH and LH were inappropriately low as post-menopausal). A subsequent MRI brain revealed an empty sella.
Following thyroid and steroid hormone replacement there was a complete resolution of the metabolic myositis (latest CK 139 Ui/L [24 170]) and significant improvement in her lipid profile.
Conclusion: This is a case of a patient with severe secondary hypothyroidism presenting with a metabolic myositis and secondary hyperlipidaemia. This went undiagnosed in primary care for almost two years with false reassurance being provided by normal TSH values.
This case highlights an atypical presentation of severe hypothyroidism. It also highlights the importance of sending a T4 in addition to TSH when hypothyroidism is clinically suspected as per British Thyroid Society guidelines.