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80 CPD ACTIVITY FROM PAGE 79 been definitively proven to either cause or not cause kidney stones. Increasing fluid intake to >2lt per day is recommended to reduce risk of kidney stones.4 Low-protein diets to slow CKD progression Conversely, restricting protein consumption, particularly in more advanced stages of CKD, has been shown to lead to greater constriction of the afferent arteriole and reductions in GFR. Over time, this slows the progression of CKD and reduces glomerular damage and proteinuria.8 Whether excessive protein intake results in CKD is a hotly debated topic. A nominal upper level of what is considered acceptable in terms of protein ingestion is in the order of 1.5 to 2g/kg/day.5 A large systematic review of 26 studies found that in the healthy population, excessive protein ingestion:9 • Is inconsistent with respect to the risk of kidney stones. • Had little or no effect on blood markers or kidney function. • Had no clear effects on blood pressure. However, the authors warn that this evidence is hampered by high risk of bias and relatively short duration of the studies (<6 months).9 Whereas, in reality, many heavy protein shake users will take these supplements for years. Of additional concern is that CKD can be a largely silent condition. The current trends of excessive doses of protein for long periods are largely untested and unregulated. Additionally, if excessive protein intake is coupled with heavy exercise, inadequate water replacement and nephrotoxic medications, the young ‘fit’ male could be at considerable risk of both AKI and CKD. AKI and dietary protein Acute kidney injury can occur quickly over days. It’s often a temporary insult to kidney function, which can resolve once the cause of the AKI is removed or treated. AKI is defined as the reduction of renal function with accompanying increases in serum urea, creatinine and accumulation of nitrogenous waste products in a patient whose renal function was otherwise normal.3 Having had an AKI can predispose to further AKIs and is a risk factor for future CKD. AKI is also frighteningly common, with seven to 25 per cent of hospitalised patients experiencing one.11 AKI is caused by a reduction of blood Figure 1. Mechanisms of AKI Acute Kidney Injury Pre-renal Reduced oral intake (dehydration) Increased fluid losses (eg, vomiting, diarrhoea, trauma, burns) Volume redistribution (eg, hepatorenal, cardiorenal, drugs including NSAIDs/ACEi/ARB) Intrinsic Glomerular injury (eg, glomerulonephritis, haemolytic-uraemic syndrome, malignant hypertension, scleroderma) Tubular injury (eg, ischaemia, sepsis, rhabdomyolysis) Interstitial injury (eg, drugs, contrast media, diuretics, penicillins, proton pump inhibitors) Post-renal (obstructive) Kidney/ureteric stones Bladder outlet obstruction (eg, prostate hypertrophy, tumours) Table 3. Risk factors for AKI Table 2. Symptoms of acute kidney injury. Counselling points for selling protein powders • Ask about other medical conditions (particularly cardiovascular disease, diabetes and renal disease). • Ask about other medicines, eg, NSAIDS, ACE/ARBS, PrEP, illicit medicines. • Advise to avoid NSAIDs if required and if they have other risk factors for AKI. • Provide advice around adequate rehydration post workout. • Counsel on signs of AKI to watch for. • Suggest rest/off days without protein supplementation. Summary There is every likelihood that as the practice of heavy protein supplementation continues, we will gather more evidence around what actually happens long term and if the fears around increase in AKI and CKD are realised. Until such time, the following points are pertinent: • CKD is common, with one in 10 Australians having signs. • A theoretical risk exists between excessive protein consumption and development of CKD. • Reviews to establish causative links have concluded that more evidence is required. • In established CKD, restricting protein intake can slow disease progression. • AKI can develop quickly. • AKI can be multifactorial, but in heavy There are a number of risk factors for AKI some of which are pre-existing and some are modifiable4 Pre-existing Modifiable • Previous AKI. • CKD. • Advanced age. • Other chronic disease such as diabetes or high blood pressure. • Smokers. • Hypovolemia. • Sepsis/shock/burns/trauma. • Radiocontrast agents. • Medications especially ACE, ARBS, NSAIDs, PreP and illicit substances, eg, ‘ice’. Water retention: puffy face, ankles, hands and feet. Nausea and vomiting. Passing less or no urine. Breathlessness. Tiredness, weakness. Loss of appetite. Itchiness. Urine red/brown colour. Pleural effusion. Convulsions. RETAIL PHARMACY • JUL 2020 flow to the kidney (pre-renal), damage to the kidney (eg, by drugs, poison, infection or injury), or blockage of urine outflow from the kidney (See Figure 1). Table 2 lists the symptoms of AKI. The pre-existing and modifiable risk factors for AKI are listed in Table 3. Strategies to avoid AKI Strategies to avoid AKI include the following:4 • Risk of AKI in our gym-going population can be lessened by ensuring adequate hydration, particularly after heavy workout sessions. • Avoidance of NSAIDs, particularly if taking other medications which may affect GFR such as ACE and ARBS, or illicit drugs which may lead to poor self- care and dehydration. • Awareness of AKI as a condition and ensuring early medical intervention is crucial to lessening the impact of AKI.