Today, it is common to hear discussions about heart health, brain health and even skin health, but perhaps less so about kidney health. Our kidneys are essential to our overall physical well-being and play critical physiological roles, such as balancing body fluid volume, removing waste products from the blood, producing erythropoietin (EPO) for maintenance of red blood cells, and many more. It is a common misconception that kidney disease/damage is rare; however, chronic kidney disease (CKD) is recognised as a leading and growing health problem worldwide, with an estimated global prevalence of between 11.7% and 15.1% in 2019 [1].
March is National Kidney Month, with World Kidney Day on 11 March. In the current climate of the COVID-19 pandemic, it is more important than ever that we remain conscious of our physical well-being and strive towards staying healthy. To raise awareness of the importance of maintaining kidney health, this article will describe the renal system, CKD and its impact on patients, and the ways in which we can all keep our kidneys healthy.
The physiology and function of the renal system
The renal system consists of the kidneys (located either side of the spine behind the abdominal cavity), ureters, urinary bladder and urethra. Each kidney comprises of approximately 1 million nephrons, which facilitate the filtering of the blood during a process called glomerular filtration [2]. This carefully balanced process removes excess fluid, ions and waste products from the blood to produce urine and maintain blood pH.
The kidneys also work in tandem with the sympathetic nervous system via the renin–angiotensin–aldosterone system to regulate blood volume [3]. In addition, the cells lining the peritubular capillaries of the kidneys produce EPO, which travels via the blood plasma to the bone marrow and stimulates the production of red blood cells; in adults, this primarily occurs in the spaces of the vertebrae, ribs, sternum and pelvis. The average adult produces approximately half a litre of blood every week and, as such, kidney disease/damage can quickly result in anaemia when EPO production is impaired [4].
Chronic kidney disease
CKD is a progressive, irreversible condition characterised by decreased kidney function (which is defined by a reduction in the glomerular filtration rate). CKD is a growing and significant public health issue that is fuelled by increasing rates of diabetes, hypertension and obesity. High blood glucose level and high blood pressure (both of which are commonly seen in obese patients or those with diabetes) can cause narrowing of and damage to the renal blood vessels, progressively reducing the effectiveness of the renal filtration system [5, 6]. In 2015, CKD was identified as the twelfth most common cause of death by a global burden of disease study [7]. Mortality increased by 31.7% between 2007 and 2017, making CKD one of the fastest-rising major causes of death worldwide, alongside diabetes and dementia [7].
Common symptoms of CKD include weight loss and poor appetite, oedema of the extremities, fatigue, nausea, and increased frequency of urination. As CKD progresses, it can cause life-threatening complications, including pericarditis, pulmonary oedema, neurological problems and significantly elevated levels of potassium in the blood (hyperkalaemia) [8]. Due to the role of the renal peritubular capillary cells in EPO production, anaemia is another common feature in CKD [9].
Management of chronic kidney disease
Although there is no cure for CKD, lifestyle changes (such as cessation of smoking, having a healthy balanced diet, reducing sodium intake and taking regular exercise) can slow progression of the disease.
Symptomatic/preventive treatments for CKD include [10, 11]:
• Antihypertensive medications, such as diuretics and angiotensin-converting enzyme (ACE) inhibitors, to lower blood pressure
• Statins to lower blood cholesterol level
• Anaemia treatments, such as iron supplements and/or erythropoiesis-stimulating agents (ESAs).
Although ESAs are an established treatment for CKD-induced anaemia, large-scale studies have identified that supraphysiological dosing of ESAs may be associated with an increased risk of cardiovascular events, vascular access thrombosis, and even CKD progression and overall mortality [12]. EPO production in the kidneys is partially stimulated by hypoxia, and novel treatments such as hypoxia-inducible factor (HIF) stabilisers and hypoxia-inducible factor prolyl hydroxylase (HIF-PH) inhibitors have demonstrated promising clinical outcomes in the past few years [12, 13].
If CKD progresses to the point that the kidneys are no longer functional, dialysis may be initiated; this is a process in which a machine is used to artificially ‘clean’ the blood when the kidneys are no longer able to perform this role. The frequency and duration of dialysis sessions typically increase as CKD progresses, which can have a major impact on the quality of life of patients.
Maintaining renal health
The complications of kidney disease not only have a devastating impact on quality of life but can also be fatal. Therefore, it is of great importance that we are aware of our kidneys and live a lifestyle that keeps our renal system healthy.
To maintain renal health [14]:
Drink plenty of water – remaining adequately hydrated ensures the kidneys function properly. This is of particular importance in warm climates.
Eat a balanced diet and maintain a healthy weight – as discussed earlier, a high blood glucose level and/or obesity can increase the risk of kidney disease. Eat a diet rich in fruit, vegetables and whole grains, and have a moderate intake of salty and fatty food.
Monitor blood pressure – high blood pressure has no symptoms but can increase your risk of kidney disease; therefore, it is important to have your blood pressure checked regularly.
Quit smoking and reduce alcohol consumption – both drinking and smoking can increase blood pressure, increasing the risk of kidney damage.
Further resources regarding renal health can be found at Kidney Care UK and Kidney Research UK. During National Kidney Month, Kidney Care UK and Kidney Research UK, alongside the British Renal Society, the National Kidney Federation, the Polycystic Kidney Disease Charity and the Renal Association, will be collaborating with the Kidney Charities Together Group to coordinate activities to raise awareness in the UK.
To learn more and get involved, please visit the World Kidney Day website. #KidneysMatter #WorldKidneyDay
References
1. Lv J-C and Zhang L-X. Prevalence and disease burden of chronic kidney disease. Adv Exp Med Biol 2019; 1165: 3–15.
2. Healthline. Kidney overview: Nephrons. Available at: https://www.healthline.com/health/human-body-maps/kidney#nephrons. Accessed February 2021.
3. Atlas SA. The renin-angiotensin aldosterone system: Pathophysiological role and pharmacologic inhibition. J Manag Care Pharm 2007; 13 (8 Suppl B): 9–20.
4. Britannica. Blood: Biochemistry. Available at: https://www.britannica.com/science/blood-biochemistry. Accessed February 2021.
5. National Institute of Diabetes and Digestive and Kidney Diseases. Diabetic kidney disease. Available at: https://www.niddk.nih.gov/health-information/diabetes/overview/preventing-problems/diabetic-kidney-disease. Accessed February 2021.
6. National Institute of Diabetes and Digestive and Kidney Diseases. High blood pressure & kidney disease. Available at: https://www.niddk.nih.gov/health-information/kidney-disease/high-blood-pressure. Accessed February 2021.
7. Neuen BL, Chadban SJ, Demaio AR et al. Chronic kidney disease and the global NCDs agenda. BMJ Glob Health 2017; 2 (2): e000380.
8. Cabrera VJ, Hansson J, Kliger AS et al. Symptom management of the patient with CKD: The role of dialysis. Clin J Am Soc Nephrol 2017; 12 (4): 687–693.
9. Jelkmann W. Regulation of erythropoietin production. J Physiol 2011; 589 (6): 1251–1258.
10. Mikhail A, Brown C, Williams JA et al. Renal association clinical practice guideline on anaemia of chronic kidney disease. BMC Nephrol 2017; 18 (1): 345.
11. National Institute for Health and Care Excellence. Chronic kidney disease: Managing anaemia. Available at: https://www.nice.org.uk/guidance/ng8/chapter/1-Recommendations#managing-anaemia. Accessed February 2021.
12. Sanghani NS and Haase VH. Hypoxia-indicible factor activators in renal anemia: Current clinical experience. Adv Chronic Kidney Dis 2019; 26 (4): 253–266.
13. Hasegawa S, Tanaka T and Nangaku M. Hypoxia-inducible factor stabilizers for treating anemia of chronic kidney disease. Curr Opin Nephrol Hypertens 2018; 27 (5): 331–338.
14. National Health Service. Keeping your kidneys healthy. Available at: https://www.nhs.uk/live-well/healthy-body/keeping-your-kidneys-healthy/?tabname=head. Accessed February 2021.
Author: India Hemming, Senior Account Executive, Porterhouse Medical
Group