Endocrine Abstracts

A 46 years old male with a background history of hypertension and asthma for which he was taking irbesartan and clenil inhaler respectively, was referred to the Endocrine service with a 3 weeks’ history of polyuria, polydipsia, nocturia and occasional headaches. On initial screening, diabetes mellitus and hypercalcemia were excluded. Initial biochemistry showed a sodium level was 144 mmol/l (135-144) with a serum osmolality of 300 mOsm/kg (275-295). A diagnosis of Diabetes Insipidus was suspected and a water deprivation test was arranged. At the start of the test, serum osmolality was 313 mOsm/kg with a urine osmolality 172 mOsm/kg (300-900). This was followed by 6 hours of polyuria with a urine output (UOP) in the range of 200-400 ml/hour and recorded weight loss of 3 kg. Following administration of 2 microgram intramuscular desmopressin (DDAVP), the urine osmolality increased to 573 mOsm/kg and the UOP fell below 100 ml/h. The results of this test were discussed at the departmental results meeting and it was unanimously concluded that this is in keeping with partial cranial diabetes insipidus (CDI). The patient was commenced on oral DDAVP 100 micrograms twice daily which resulted in improvement in the urinary frequency and resolution of the nocturia. MRI scan of the pituitary gland showed thickening and enhancement of the entire infundibulum and a primary infundibular lesion was suspected. The anterior pituitary hormone profile showed secondary hypogonadism (Table 1).During follow-up, the patient mentioned a 2 months history of left arm and hand weakness together with right-sided jaw pain. On clinical examination there was evidence of reduced left upper limb power (3/5) with brisk reflexes and an extensor plantar response bilaterally. XR orthopantomogram showed significant destruction of the right mandible. A PET-CT confirmed a destructive and metabolically active lesions in the mandible and left scapula. At this stage, LCH and Erdheim-Chester disease were considered as differentials and the biopsy of the mandible revealed histology consistent with a diagnosis of LCH. He was referred to the Oncology service for chemotherapy. From an Endocrinological stand point, his symptoms were well controlled on DDAVP 200 mg (0600 hours), 50 mg (1400 hours) and 200 mg (2200 hours).