Endocrine Abstracts

Introduction: Secondary hypothyroidism can be a difficult diagnosis to make in patients presenting with fatigue. About 30% of females can develop hypopituitarism post-partum and report symptoms after losing any of the anterior pituitary hormone axis. Central hypopituitarism can occur secondary to various structural and vascular abnormalities but can present with pure hormonal abnormalities.

Case: We present a case of a woman in her late thirties, who presented to the Endocrinology clinic with worsening fatigue, hair loss, weight gain, floaters and dry eyes for 4 years. She felt that her symptoms started post-partum and originally diagnosed with post-partum thyroiditis treated with oral Levothyroxine 125 mg which did not alleviate her symptoms. She denied any thyroid related illness.

Investigations: Her serial TSH were consistently low with normal Free T4 (negative TSH receptor antibodies). Further anterior pituitary screen showed a deficiency of TSH, LH and FSH which raised a strong suspicion of possible central hypopituitarism. This patient’s thyroid ultrasound excluded thyroiditis but her Pituitary MRI scan showed a 2mm cystic micro-adenoma or Rathke’s cyst confirming her diagnosis.

Management and Discussion: Our case highlights the challenge of differentiating between primary and secondary hypothyroidism. In above patients case her serum TSH was used to titrate her oral Levothyroxine which aggravated her symptoms. This patient showed an improvement in her symptoms after diagnosis was revised to secondary hypothyroidism which was treated with much higher dosage of oral Levothyroxine. This dosage titration is based on her clinical symptoms instead of using her body weight as a reference for estimating her daily requirements. All these decisions around complex decision making have to be undertaken in an MDT setting for this group of patients.