Case Report A case of severe hyperkalaemia presenting with cardiac arrythmias: An uncommon initial manifestation of chronic kidney disease

Hyperkalaemia is a potentially fatal condition. The relationship between potassium (K + ) level and symptoms may not be consistent, as patients with longstanding hyperkalaemia may be asymptomatic in spite of high K + levels 1 . The rapidity of change in K + level influences the symptoms observed at any particular K + concentration1. The most dangerous complication in patients with hyperkalaemia is cardiac arrhythmia. It is known that a K+ concentration greater than 10mmol/L is fatal, unless urgent treatment is instituted 2,3 . This report describes a patient presenting with a cardiac arrythmia and extremely severe hyperkalaemia (9mmol/L) of uncertain duration, who subsequently recovered with medical management.


Introduction
Hyperkalaemia is a potentially fatal condition. The relationship between potassium (K + ) level and symptoms may not be consistent, as patients with longstanding hyperkalaemia may be asymptomatic in spite of high K + levels 1 . The rapidity of change in K + level influences the symptoms observed at any particular K + concentration 1 . The most dangerous complication in patients with hyperkalaemia is cardiac arrhythmia. It is known that a K + concentration greater than 10mmol/L is fatal, unless urgent treatment is instituted 2,3 . This report describes a patient presenting with a cardiac arrythmia and extremely severe hyperkalaemia (9mmol/L) of uncertain duration, who subsequently recovered with medical management.

Case history
A 56 year old male presented to hospital with shortness of breath, fever and reduced urine output of two days duration. He was on treatment with metformin and losartan for diabetes and hypertension.
On admission he was breathless with an oxygen saturation of 95 percent on room air and his blood pressure was 150/70mmHg. The cardiac monitor showed a broad complex tachycardia of 150 beats/min followed by nodal bradycardia. He was haemodynamically unstable during the episodes of bradycardia.
The electrocardiogram (ECG) showed tall T waves and broad QRS complexes ( Figure 1) progressing to sine waves (arrow). His initial serum K + level was repeatedly 9mmol/L and serum creatinine (SCr) was 682μmol/L. Urine microscopy showed 10-15 pus cells/HPF. Several ECGs were taken while the results of K + concentration were awaited and all were compatible with severe hyperkalaemia (Figures 2, 3, 4). The results of his investigations are summarized in Table1.
The patient was treated with two doses of intravenous calcium gluconate along with two infusions of intravenous soluble insulin 10 units in 50ml of 50% dextrose within a period of 30 minutes. Subsequently, his cardiac rhythm reverted to sinus tachycardia with mild ST segment depression and T wave inversion in the lateral leads ( Figure 5).
Although the serum K + concentration improved with medical management, it remained high (6.5mmol/L) and he was commenced on hemodialysis. The patient was discharged on day eight and at one month review he remained clinically stable with a K + level of 4.2 mmol/L and a SCr of 380μmol/L.

Discussion
Hyperkalaemia is a common complication of chronic kidney disease. Our patient's most recent SCr had been done two years ago and was within normal limits. He had been treated with losartan over a long period without being monitored for hyperkalaemia. The most likely explanation for our patient's severe hyperkalaemia was acute-on-chronic kidney disease precipitated by urinary sepsis with a possible contribution from losartan therapy.
It is known that hyperkalaemia can cause cardiac arrhythmias. 1 This report illustrates a case presenting with extremely severe hyperkalaemia as the first clinical manifestation of chronic kidney disease. The patient survived with medical management. A high index of suspicion of this potentially life-threatening complication should be maintained in high-risk patients. ECG is a readily available and convenient investigation to quickly diagnose hyperkalaemia, especially when severe. Hyperkalaemia should be suspected in any patient with chronic kidney disease with a new onset arrhythmia.