Endocrine Abstracts

An NHS Patient Safety Alert in 2016 warned “Risk of severe harm or death when desmopressin (DDAVP) is omitted or delayed in patients with cranial diabetes insipidus”. Endocrinologists added “It (DDAVP) needs to be continued in all situations with the assistance of endocrine teams”.

Case report: A 63 year old male was referred with a sodium of 116 mmol/l following a re-do hip replacement 2 weeks earlier. A progressive decline in sodium levels from normal had occurred over the post-operative period. Cushing’s disease diagnosed by us 20 years earlier was treated with radiotherapy (37.5 Gy in 15 fractions) following failed pituitary surgery. ACTH had decreased but remained elevated. Moderately severe diabetes insipidus (urine volumes 6.8-9.7 L/24h) was also confirmed. Follow-up was elsewhere. Examination found him to be unwell, confused and hypotensive receiving intravenous antibiotics and DDAVP 100 mg bd orally. The impression formed was one of profound worsening hyponatraemia due to (1) Remnant endogenous SIADH secondary to stress/infection superimposed on diabetes insipidus (2) Secondary hypoadrenalism secondary to previous pituitary radiotherapy with impaired free water clearance (3) A combination of (1) and (2). Investigations prior to treatment (at 17:00h) confirmed sodium 115 mmol/l and cortisol 100 nmol/l. An add on (09:00h same day) cortisol was 93 nmol/l. DDAVP was stopped and administration of intravenous normal saline/hydrocortisone normalised sodium over 64 h with symptomatic improvement. Case review led to: a plan to identify DDAVP treated patients and to provide them with a DDAVP card; hospital pharmacists to inform the endocrine team of DDAVP treated patients on admission; and education for clinical staff on the DDAVP patient safety alert. This case confirms the need for early endocrine input to patients with cranial diabetes insipidus and that DDAVP should be continued in most, but not all, patients.