Life-threatening lithium-induced diabetes insipidus after colonic surgery: a report of two cases

Colonic surgery is associated with major disturbances to patients’ fluid balance as a result of pre-operative starvation, intra-operative blood loss, insensible losses, and post-operative ‘third space’ losses. In the post-operative period, junior surgeons are well trained to manage oliguria, but have little experience of the management of post-operative polyuria. Nephrogenic diabetes insipidus occurs in 12% of patients on lithium therapy and may present in the immediate post-operative period with massive polyuria, profound dehydration and life threatening hypernatraemia, as patients are unable to ingest large volumes of fluid orally. We report two cases, one life threatening, of lithium induced nephrogenic diabetes insipidus (LINDI) which presented in the early postoperative period after emergency colonic surgery whilst the patients were denied oral intake. The first patient attained a peak serum sodium concentration of 185mmol/l and required ventilation after a respiratory arrest. We suggest any surgical patient who describes a history of bipolar disorder or lithium therapy should be questioned directly to ascertain confirmatory features of LINDI, and have post-operative polyuria treated with aggressive fluid replacement