Acute severe diarrhoea and hyponatremia after zoledronic acid infusion: an acute phase reaction

Zoledronic acid (ZA), an intravenous aminobisphosphonate, is prescribed widely for postmenopausal osteoporosis. It is a relatively safe drug but may cause adverse effects including acute phase reaction. Oral non-aminobisphosphonates are known to cause diarrhoea that is usually mild and self-limited. Intravenous amino-bisphosphonates are not known to cause diarrhoea. We describe a case of acute watery diarrhoea complicated by severe hyponatremia and hypotension following ZA infusion. The patient needed intensive care for four days. To the best of our knowledge, this type of acute diarrhoea complicated by severe hyponatremia, following ZA infusion, is not reported so far. Strong temporal relation with ZA administration makes it the most likely cause. Furthermore, all laboratory and imaging parameters indicate that the secretory diarrhoea may be a component of acute phase reaction. According to World Health Organization (WHO) causality scale, ZA was a probable cause of acute watery diarrhoea in our patient. Clinicians should be aware that ZA administration can cause acute watery diarrhoea and may lead to severe hypotension and hyponatremia.