Endocrine Abstracts

21 year old man presented to the emergency department with hypotensive shock. He had been seeing the GP with complains of poor appetite, intermittent vomiting, increased thirst and postural dizziness for the last 6 months. Previous medical history included tonsillitis, gastritis and learning difficulties. The working differential was severe gastroenteritis with hypovolemic shock, and so he was given immediate fluid resuscitation. He remained hypotensive, and so was given empirical steroids to good effect. The following day, he developed polyuria prompting endocrinology review. Examination revealed scarcity of facial hair,small volume testes (Tanner stage 3) but no visual field defect to confrontation. Investigation then confirmed diabetes insipidus (which is likely to have been unmasked by glucocorticoid treatment) and panhypopituitarism. The presenting serum sodium was 156 mmol/l (133–146 mmol/l), serum osmolality 320 mmol/kg (275–295 mmol/kg) with urine osmolality 187 mmol/kg (40–1200 mmol/kg). Cortisol was 83 nmol/l (101–536 nmol/l),Growth Hormone 0.26 ug/l, IGF1 3.2 nmol/l (11.3–56.6), Testosterone <0.4 nmol/l (8.6–29), lH, <0.2 IU/l (3–8 IU/l), FSH<0.2 IU/l (<8 IU/l), Prolactin 1102 mIU/l (53–360 mIU/l). FT4 7 pmol/l (8–21),TSH 0.37 mU/l (0.35–3.5) and similar TFTs noted 1 year earlier on electronic record. Autoimmune screen and serum tumor markers including hCG were normal. CXR was unremarkable. MRI showed wide spread abnormal signal around the pineal gland extending anteriorly to the hypothalamus and optic chiasm suggestive of a pineal gland germ cell tumour with local invasion. Subsequent analysis of the cerebral spinal fluid showed elevated hCG 10.83 IU. The patient was initiated on hydrocortisone, levothyroxine, desmopressin and testosterone and discussed at the regional pituitary neuro-oncology MDT. Craniotomy and open biopsy confirmed the presence of a pineal gland germinoma. He then received 24Gy radiotherapy in 15 fractions and remains extremely well at 20 months follow up but has become partially sighted. Pineal gland tumors represent around 1% of all primary intracranial tumours and can be subdivided into germ cell and non germ cell types. These typically manifest in adolescence with endocrine dysfunction, disruption of growth and puberty. These tumours are remarkably radiosensitive but optimal treatment varies according to pathology requiring a tissue diagnosis wherever possible. In this case, three clues to the eventual diagnosis might have been spotted earlier. Vomiting beyond 2 weeks should prompt a search for underlying causes. Prolonged delay of growth and puberty should prompt a detailed physical evaluation and a basic endocrine assessment. Finally, a low T4 in the context of low or normal TSH i.e secondary hypothyroidism, should also prompt an endocrine referral.