Download The Potential Impact Of Potassium Salt Replacement In Food

THE POTENTIAL IMPACT OF POTASSIUM SALT REPLACEMENT IN FOOD
Does the Risk Outweigh the Benefit?
INTRODUCTION: Current National and International guidelines advise a salt intake in the
general population of <6g/day. The Food Industry has suggested substituting potassium (K+)
salts for sodium salts when salt is required for manufacture eg. baked produce. This may lead to
an increase in the population K+ intake. There is concern that is high risk populations, including
those with CKD and the elderly, this may lead to life-threatening hyperkalaemia. There is
currently little published information on the burden of hyperkalaemic events presenting from
the community and those at-risk individuals would be known to medical services to be provided
with dietary restriction advice. The Food Standards Agency has been performing a risk-benefit
analysis to advise Government policy. As part of this work we aimed to establish the baseline
burden of hyperkalaemia in a population presenting to secondary care and identify the presence
of underlying risk factors in a subpopulation with potentially life-threatening hyperkalaemia.
METHODS: A retrospective electronic data search of pathology results identified patients
>18years presenting to the Emergency Department (ED) or Acute Medical Unit (AMU) of an
Acute Hospital Trust from January-April 2014 with an elevated serum K+ concentration
(>5.3mmol/l). Demographic, clinical and social data was collected from accessible medical case
notes for those patients with K+≥6.0mmol/l (termed severe hyperkalaemia).
RESULTS: This hospital trust comprises two acute hospital sites with a catchment population
of approximately 492,000, with 7,535 admissions through ED January-March 2011. Over 4
months [January-April 2014] 219 cases presented to the ED/AMU across the two sites with
elevated K+. 160 cases (73%) had readings of <6.0mmol/l. 59 cases had severe hyperkalaemia;
39 presented to one site and were analysed further. 22 cases (56%) had K+ 6.0 to <6.5, 8 cases
(21%) 6.7 to <7, 4 (10%) 7 to <7.5, 3(8%) 7.5 to <8 and 2 (5%) > 8mmol/l. These 39 episodes
related to 37 individual patients, 20 men, mean age 75±15 years. 23 (62%) had hypertension, 16
(45%) diabetes mellitus, 6 (17%) heart failure and 4 (11%) peripheral vascular disease. All
patients had at least one significant medical condition; 34 (92%) had ≥2 co-morbidities and 27
(73%) ≥3. 36/37 patients had a previously documented creatinine; 27 patients (75%) had an
historical eGFR <60ml/min/1.732 (7 Stage 3a CKD, 8 Stage 3b, 4 Stage 4, 7 Stage 5-dialysis
dependent, 1 Stage 5-dialysis independent). Regarding previous contact with hospital services;
in addition to the 7 patients on RRT, 12 were under regular renal outpatient follow up and there
was previous out-patient hospital activity in the index trust in 31 patients. Admission prescribed
medications were recorded in 36/39 episodes, 67% were on at least one medication associated
with hyperkalaemia risk (17% on 2, 8% on 3); 12 were taking ACE-inhibitor or angiotensin
receptor blocker, 1 spironolactone, 1 NSAIDS, 3 non-selective betablocker, 4 trimethoprim and
1 tacrolimus. From the social history, a conservative estimate of at least 35% of patients would
be unlikely to prepare their own meals. 2 patients presented with cardiac arrest associated with
hyperkalaemia (K+ 8.7mmol/l [patient survived but readmitted 10 weeks later with 6.3mmol/l
and died shortly thereafter] and 7.6mmol/l), a 3rd patient died within twelve hours of presenting
with K+ 6.2mmol/l. A further 5 patients survived less than 14 days post admission. ECG
documentation was incomplete, but profound hyperkalaemic changes were seen in 4 patients
(K+ 8.7, 9.1, 7.5, 7.6mmol/l respectively). Excluding those patients on renal replacement
therapy (RRT=7), 21% of patients had no AKI, 24% Stage 1, 17% Stage 2, 38% Stage 3. 13
(33%) of patients were admitted with sepsis. Of 35 episodes with recorded bicarbonate 17 were
≤15mmol/l (49%). Admission systolic blood pressure was ≤100mmHg in 10 cases (28%).
CONCLUSIONS: Hyperkalaemia presenting as an emergency in the majority of cases is mild.
However, patients presenting with severe hyperkalaemia in the setting of critical illness had a
high associated mortality. These patients are elderly, multimorbid and taking exacerbating
medications. Most of these patients have previously identifiable risk factors for AKI and
hyperkalaemia, and previous contact with clinical services. This risk of increased potassium
supplementation in food should be weighed carefully with the adverse outcome we found in
those individuals most at risk.