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 Table of Contents  
Year : 2017  |  Volume : 24  |  Issue : 4  |  Page : 254-256

Preoperative bowel preparation complicated by lethal hypermagnesaemia and acute nephropathy

Department of Anaesthesia, University of British Columbia, Vancouver, BC, Canada

Date of Web Publication18-Jan-2018

Correspondence Address:
Dr. Olumuyiwa A Bamgbade
Department of Anaesthesia, University of British Columbia, Vancouver, BC
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/npmj.npmj_145_17

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Hypermagnesaemia is an uncommon but serious disorder. An elderly woman presented with severe cardiovascular collapse, neurologic depression and acute nephropathy, following bowel preparation. Urgent laboratory tests revealed serum magnesium level of 7.5 mmol/L (normal = 0.75–1.05 mmol/L). Prompt resuscitation and treatment of the hypermagnesaemia included intravenous calcium chloride as a physiological antagonist, fluid infusion and frusemide to aid renal excretion of magnesium. There are few case reports of patients who survived hypermagnesaemia levels >7 mmol/L. This is a case report of near-fatal hypermagnesaemia which resolved following early diagnosis and treatment. Hypermagnesaemia may be difficult to diagnose because serum magnesium is not checked routinely and many clinicians are unfamiliar with this uncommon condition. It is a diagnosis of exclusion and may not be recognised as a cause of neurologic or cardiorespiratory depression. Hypermagnesaemia should be considered as a possible diagnosis in elderly or high-risk patients presenting with such symptomatology.

Keywords: Acute nephropathy, bowel preparation, hypermagnaesaemia, pre-operative, shock

How to cite this article:
Bamgbade OA. Preoperative bowel preparation complicated by lethal hypermagnesaemia and acute nephropathy. Niger Postgrad Med J 2017;24:254-6

How to cite this URL:
Bamgbade OA. Preoperative bowel preparation complicated by lethal hypermagnesaemia and acute nephropathy. Niger Postgrad Med J [serial online] 2017 [cited 2022 Sep 28];24:254-6. Available from: https://www.npmj.org/text.asp?2017/24/4/254/223463

  Introduction Top

Magnesium is an important electrolyte in various human physiologic and pathologic processes.[1],[2] Magnesium is frequently used in various contemporary medical therapies.[3],[4] It is a component of laxatives and bowel preparation agents.[4],[5] Sodium picosulphate magnesium citrate (SPMC) is a common bowel preparation agent.[4] Magnesium therapy may be complicated by severe hypermagnesaemia.[6],[7],[8],[9],[10] Hypermagnesaemia is an uncommon but serious or deadly disorder. Hypermagnesaemia may be difficult to diagnose, and many clinicians are unfamiliar with this uncommon condition. There are few case reports of patients who survived severe hypermagnesaemia.[7],[8] This is a case report of lethal hypermagnesaemia that was promptly diagnosed and successfully treated.

  Case Report Top

An 82-year-old female who was being managed for colon carcinoma was rushed to the emergency room of Prince George Hospital, British Columbia, Canada, on the proposed day of surgery; in May 2016. She was in shock, with blood pressure of 60/45 mmHg, pulse rate of 114/min, oxygen saturation of 91% on room air, respiratory rate of 28/min, lethargy and Glasgow coma score (GCS) of 13. Her morbidities included colon cancer, chronic constipation, hypertension and hypothyroidism. Her regular medications included ramipril 5 mg daily, aspirin 81 mg daily and levothyroxine 50 μg daily; but these had been omitted for 24 h.

Before the emergency room presentation, the patient was scheduled for laparotomy and sigmoid colectomy. She was given written instructions to consume low-fibre diet for 3 days preoperatively and to fast 8 h preoperatively. She was given written instructions to dilute one sachet of SPMC in 150 ml of water and ingest 24 h preoperatively followed by drinking 2 l of clear fluid. She was instructed to dilute another sachet of SPMC in 150 ml of water and ingest 8 h preoperatively followed by drinking 2 l of clear fluid. The patient's daughter supervised the conduct and completion of the bowel preparation in their family home. Pre-operative investigations including electrocardiography (ECG), chest X-ray, urinalysis, serum biochemistry, coagulation and full blood count were completed 1-week previously and were normal.

Following her admission to the emergency room, urgent resuscitation was commenced, and investigations were performed. Her serum magnesium was 7.5 mmol/L (normal = 0.75–1.05 mmol/L), total calcium was 2 mmol/L, potassium was 5.2 mmol/L, urea nitrogen was 19 mmol/L, creatinine was 131 μmol/L, glucose was 5.7 mmol/L and estimated glomerular filtration rate was 40. Urine specific gravity was 1.040 and arterial blood gas (ABG) showed mild metabolic acidosis. Her 12-lead ECG showed bradycardia, junctional escape rhythm and left bundle branch block.

Urgent treatment of hypermagnesaemia was performed. Two 16-guage intravenous (IV) cannulae were inserted in the patient's left forearm. Resuscitation comprised IV calcium chloride 1 g, Voluven ® 500 ml bolus and normal saline 500 ml/h. IV frusemide 40 mg was subsequently administered to enhance renal excretion of magnesium. Her treatment was monitored by pulse oximetry, respiratory rate, ECG, non-invasive blood pressure, temperature, urine output, GCS, central venous pressure through right internal jugular central venous cannulation and direct blood pressure through the left radial arterial line. After 6 h of resuscitation, repeat measurements showed improved clinical state and satisfactory cardiovascular, neurologic, renal, ABG and laboratory parameters. Her serum magnesium was 1.01 mmol/L.

About 12 h after recovery from hypermagnesaemia, the patient underwent sigmoidectomy and stapled colorectal anastomosis under general anaesthesia. The intra-operative course was uneventful. Her immediate post-operative care on the high dependency unit was uneventful. Repeat measurements at 24 h showed normal cardiovascular, neurologic, renal, ABG and laboratory parameters. Her serum magnesium was 0.8 mmol/L. She was successfully transferred to the surgical ward after 24 h and was discharged home on the 8th post-operative day.

  Discussion Top

Oral SPMC consists of sodium picosulphate (stimulant laxative) and magnesium citrate (osmotic laxative). It is a popular agent for bowel preparation. An extensive systematic review showed that SPMC is better than polyethylene glycol, bisacodyl or sodium phosphate; in terms of bowel cleansing adequacy, low drink volume, safety, patient satisfaction, tolerability, compliance, robust protocol for use, insignificant absorption and side effects.[4] A randomised blinded study showed that the side effects of SPMC are usually mild and mainly gastrointestinal including nausea, vomiting, abdominal bloating and cramps.[5]

Magnesium therapy, such as in SPMC, is acceptable and safe. Magnesium is mainly excreted renally; therefore, hypermagnesaemia usually occurs in patients with nephropathy. Some case reports showed that hypermagnesaemia may occur in elderly patients without renal impairment, especially in association with gastrointestinal disorders such as peptic ulcer, gastritis, colitis, constipation, hypomotility, dilation or perforation.[7],[8],[9] This patient's hypermagnesaemia was probably precipitated by colon cancer, elderly age and acute nephropathy. This indicates that magnesium-containing medications should be used cautiously in elderly and high-risk patients.

Two systematic reviews showed that bowel preparation is associated with dehydration, hypovolaemia, electrolyte anomaly and nephropathy.[4],[6] A systematic review showed that the incidence of nephropathy is 1%–4%; and risk factors include dehydration, elderly age, chronic hypertension and use of angiotensin antagonists.[6] Although the patient in the current report did not have pre-existing renal dysfunction, she had all the risk factors for nephropathy as listed above. Her pre-operative bowel preparation was probably associated with dehydration and hypovolemia, and the pathophysiology was further complicated by nephropathy. Despite supervision by her family, it is possible that this elderly patient did not drink enough fluid during the 24 h period of bowel preparation when she should have consumed at least 4 l of fluid. This report indicates that optimal hydration must be ensured, and renal function should be monitored during and after bowel preparation; especially in elderly or high-risk patients. Furthermore, patients on angiotensin antagonists are prone to acute renal impairment during periods of dehydration or hypovolemia such as precipitated by bowel preparation in this patient in the current report. Therefore, angiotensin antagonists should be omitted 24 h before and after bowel preparation.

Hypermagnesaemia is an uncommon but serious disorder.[7],[8],[10] Some case reports have shown that it may be a clinically unrecognised cause of neurologic and/or cardiorespiratory depression.[9],[10] It should be considered in elderly or high-risk patients presenting with suggestive symptomatology; such as shown in [Table 1]. Hypermagnesaemia is difficult to diagnose. It is not usually detected because serum magnesium is not checked routinely and many clinicians are unfamiliar with this uncommon condition. A high index of suspicion enhances prompt diagnosis and therapy. This patient's clinical features led to suspicion of hypermagnesaemia, which necessitated comprehensive tests including serum magnesium. The test results promptly revealed the definitive diagnosis of hypermagnesaemia. This highlights the importance of serum magnesium level assay in patients with neurologic or cardiorespiratory depression.
Table 1: Clinical features of hypermagnesaemia in human physiologic systems

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Hypermagnesaemia therapy usually includes IV calcium as a physiological antagonist, fluid resuscitation and frusemide to aid renal excretion of magnesium.[7],[8] The patient in this current report received the standard treatment. Patients with unrecognised hypermagnesaemia usually require multiorgan support on Intensive Care Unit (ICU) until the diagnosis is eventually made. However, patients with prompt diagnosis usually receive early simple therapy, have better outcomes and avoid costly complex ICU care. There are rare case reports of patients who survived hypermagnesaemia levels >7 mmol/L.[7] The patient in the current report survived severe hypermagnesaemia of 7.5 mmol/L, with prompt, successful therapy that was enabled by prompt diagnosis.

  Conclusion Top

Hypermagnesaemia is a serious clinical condition with high fatality rate if not recognised and managed early. Therefore, prompt diagnosis and treatment ensure a successful outcome.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.


Institutional support is acknowledged, but there was no source of funding.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Oladipo OO, Ajala MO, Okubadejo N, Danesi MA, Afonja OA. Plasma magnesium in adult Nigerian patients with epilepsy. Niger Postgrad Med J 2003;10:234-7.  Back to cited text no. 1
  [Full text]  
Okusanya BO, Garba KD, Ibrahim HM. The efficacy of intramuscular loading dose of mgSO4 in severe pre-eclampsia/eclampsia at a tertiary referral centre in Northwest Nigeria. Niger Postgrad Med J 2012;19:77-82.  Back to cited text no. 2
Bamgbade OA. Intraoperative magnesium supplementation improves gynecology major surgery perioperative outcome. J Clin Anesth 2017;44:21.  Back to cited text no. 3
Hoy SM, Scott LJ, Wagstaff AJ. Sodium picosulfate/magnesium citrate: A review of its use as a colorectal cleanser. Drugs 2009;69:123-36.  Back to cited text no. 4
Munsterman ID, Cleeren E, van der Ploeg T, Brohet R, van der Hulst R. 'Pico-Bello-Klean study': Effectiveness and patient tolerability of bowel preparation agents sodium picosulphate-magnesium citrate and polyethylene glycol before colonoscopy. A single-blinded randomized trial. Eur J Gastroenterol Hepatol 2015;27:29-38.  Back to cited text no. 5
Lien YH. Is bowel preparation before colonoscopy a risky business for the kidney? Nat Clin Pract Nephrol 2008;4:606-14.  Back to cited text no. 6
Kontani M, Hara A, Ohta S, Ikeda T. Hypermagnesemia induced by massive cathartic ingestion in an elderly woman without pre-existing renal dysfunction. Intern Med 2005;44:448-52.  Back to cited text no. 7
Uchiyama C, Kato T, Tomida K, Suzuki R, Nakata K, Hamanaka M, et al. Fatal hypermagnesemia induced by preoperative colon preparation in an elderly woman: Report of a case. Clin J Gastroenterol 2013;6:105-10.  Back to cited text no. 8
Clark BA, Brown RS. Unsuspected morbid hypermagnesemia in elderly patients. Am J Nephrol 1992;12:336-43.  Back to cited text no. 9
Onishi S, Yoshino S. Cathartic-induced fatal hypermagnesemia in the elderly. Intern Med 2006;45:207-10.  Back to cited text no. 10


  [Table 1]

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