Endocrine Abstracts

Clinical Case: A 30-year-old female was referred with subfertility and hypogonadotropic hypogonadism. She had systemic lupus erythematosus (SLE) and was on maintenance 5 mg prednisolone, having received intermittent high doses since her diagnosis in 2018. She reported 12 months of amenorrhea and reduced libido without galactorrhoea, despite regular menses since menarche aged13. This coincided with a rapid weight gain of 20 kg. On examination, her BMI was 36.8 kg/m², presenting with acanthosis nigricans, an intrascapular fat pad, centripetal obesity, and violaceous striae, without proximal myopathy or visual field deficits. As her SLE was presumed quiescent and following discussion with her rheumatologist, prednisolone was discontinued to allow assessment of her hypothalamic-pituitary-adrenal axis off glucocorticoids. However, she continued to gain a further 10 kg in weight over the following 8 months. Upon further inquiry, she reported compulsive eating, polydipsia with polyuria, and worsening cognition, predating discontinuation of glucocorticoids.

Investigations: Her initial 0900 hours pituitary profile off glucocorticoids while amenorrhoeic revealed: oestradiol 91 nmol/l, LH 4.1 u/l, FSH 6.4 u/l, prolactin 568 (0-495 mU/l), ACTH 20 (<50 ng/l), cortisol 198 nmol/l, free T4 14.2 pmol/l, TSH 1.94 mU/l.

Results and Treatment: At follow-up, she was also hypernatremic (153 mmol/l; reference range: 135–145 mmol/l) with hyperosmolar serum (309 mmol/kg; reference range: 275–295 mmol/kg) and dilute urine (149 mmol/kg; reference range: 50-1200 mmol/kg). She maintained normocalcemia and euglycemia. Self-recorded fluid balance averaged 7000 ml intake and 6000 ml output. Oral desmopressin titrated to 200 mg twice daily controlled polyuria, and pituitary MRI reported absence of the posterior pituitary bright spot. She was subsequently diagnosed with arginine vasopressin deficiency (AVP-D) presumed due to autoimmune hypophysitis (AH). Cortisol of 11 nmol/l following 48 hr low-dose dexamethasone testing excluded endogenous Cushing’s syndrome driving weight gain and cognitive decline. Moreover, an MRI head showed changes consistent with hypothalamitis, likely contributing to her cognitive impairment and hyperphagia. She received pulsed intravenous methylprednisolone under the guidance of the neurologists. A multidisciplinary team discussion concluded that both her hypothalamitis and AH were likely due to SLE. Other differentials such as sarcoidosis and other neuro-inflammatory conditions were excluded.

Discussion: The co-existence of autoimmune hypothalamitis (ATA) and AH due to SLE, presenting with AVP-D and hypothalamic hyperphagia, is rare. Glucocorticoids are first-line therapy; while radiological improvement is described, endocrine recovery is not assured, and cognitive outcomes vary. Occasionally, biologics such as Rituximab are necessary to prevent progression and/or achieve remission. Currently, our patient is on weaning prednisolone, desmopressin, and hormone replacement therapy, awaiting re-evaluation of radiology, cognition, and pituitary function under multidisciplinary care.