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Think about the kidneys in your medico-legal practice
- Jan 16, 2023
- Latest Journal
by Dr. Adnan Sharif
Consultant Nephrologist and Transplant Physician
The spectrum of kidney disease
Patients with kidney disease can have different clinical presentations. Some have symptoms or signs that are directly related to the kidney (such as visible blood in the urine) or due to a reduction in kidney function (fluid retention, hypertension, kidney failure symptoms). However, the majority of patients have no symptoms and are incidentally found to have kidney problems because of a detectable abnormality in their blood tests, urine samples or radiological scans. As these investigations are commonly performed in healthcare, kidney problems may exist which are easy to detect but frequently overlooked in medico-legal cases.
Kidney problems will generally cause acute, sub-acute, or chronic health problems. When a kidney abnormality is detected, often a detailed investigation of records is required to determine whether the kidney injury is acute or more common (referred to as chronic kidney disease which affects 10-15% of the general population). Acute kidney injury (AKI) is an important medical problem that develops over hours to days and can be diagnosed in the community or after hospitalisation. AKI is very common and can be seen in over a quarter of hospital episodes. Therefore, AKI is likely to occur in many medical-legal cases, either as the main complication or more commonly as a co-existing complication. However, despite their importance, the kidneys are frequently ignored or overlooked in these cases.
What do our kidneys do?
Kidneys are critically important for healthy wellbeing. Their primary job is to look after our bodies through the production of urine to remove excess water and toxins, but they also have other important hormonal roles. In summary, our kidneys:
• Get rid of waste products and many other toxins through production of urine
• Regulate water balance to ensure we never have too much or too little water in our body
• Help control your heart rhythm by maintaining a balance of electrolytes (e.g. potassium, sodium, calcium) that are important for heart rhythm
• Regulate acid-base balance to ensure blood is never too acidic or alkaline
• Control blood pressure through different mechanisms to ensure blood pressure is not too high or low
• Help your bones by activating vitamin D to help bones absorb calcium
• Make blood by releasing the hormone erythropoietin which tells bone marrow to make red blood cells
That is why AKI, as a sudden and recent reduction in a person’s kidney function, can have dramatic implications and consequences for good health. AKI is important from a medico-legal perspective because it is common, associated with bad outcomes and has lots of risk factors. AKI may be the main problem or (more commonly) occur as a consequence of other medical or surgical problems.
Who is at risk of developing AKI?
AKI should be considered for individuals with acute illness. Guidance from the National Institute for Health and Care Excellence (NICE) suggests increased awareness of AKI is necessary if any of the following are likely or present:
• chronic kidney disease (adults with an estimated glomerular filtration rate [eGFR] less than 60 ml/min/1.73 m2 are at particular risk)
• heart failure
• liver disease
• diabetes
• history of acute kidney injury
• oliguria (urine output less than 0.5 ml/kg/hour)
• neurological or cognitive impairment or disability, which may mean limited access to fluids because of reliance on a carer
• hypovolaemia
• use of drugs with nephrotoxic potential (such as nonsteroidal antiinflammatory drugs [NSAIDs], aminoglycosides, angiotensinconverting enzyme [ACE] inhibitors, angiotensin II receptor antagonists [ARBs] and diuretics) within the past week, especially if hypovolaemic
• use of iodinated contrast agents within the past week
• symptoms or history of urological obstruction, or conditions that may lead to obstruction
• sepsis
• deteriorating early warning scores
How do we detect AKI?
AKI is normally diagnosed by a blood test to measure the level of creatinine in the blood. If the creatinine level has doubled, then there is severe AKI and urgent treatment is normally necessary. If the creatinine level has gone up by a lesser amount, then there may need to be follow up checks in the next few days. However, this is less of an emergency and may be managed in primary care. AKI can also be detected based upon a drop in urine production in hospitalised people, but this is less common.
Often people with AKI have no symptoms, or have symptoms of the underlying cause that has caused AKI (e.g. infection), but some complaints people may have include:
• feeling sick or being sick
• diarrhoea
• dehydration
• peeing less than usual
• confusion
• drowsiness
Incidence and outcomes of AKI
AKI is an important medical problem because firstly it is very common. Around 1 in 4 adult hospital admissions are associated with AKI, with 1 in 2 adult critical care admissions being associated with AKI. Approximately a third of patients with AKI in hospital develop their AKI episode during their stay in hospital, while two-thirds of patients with AKI in hospital had AKI at the time of admission.
The second reason why AKI is important is because it is associated with excess death. Back in 2009, the National Confidential Enquiry into Patient Outcome and Death (NCEPOD) AKI report found that in the UK up to 100,000 deaths each year in hospital are associated with acute kidney injury and up to 30% could be prevented with the right care and treatment. The majority of AKI is caused by sepsis, poor hydration and medication but other causes exist including renal tract obstruction and intrinsic renal disease. AKI is associated with high mortality rates; from 8 to 18%, 22–33%, and 32–36% mortality for patients with AKI stages 1, 2, and 3 respectively, whilst in the absence of AKI, mortality runs at 2%. Even in the absence of death, AKI can have short-term and long-term health issues for survivors including heart disease, chronic kidney disease and risk for developing kidney failure.
Since the NCEPOD report, great strides have been made in hospital AKI care, including the introduction of AKI algorithms to detect AKI and national advice on what an AKI bundle should include. There is greater awareness of clinically recognised risk factors for AKI, both modifiable (e.g. use of iodinated contrast, use of certain medications) and non-modifiable (e.g. age, presence of chronic kidney disease) providing greater opportunity to prevent the development of AKI with appropriate intervention. For example, staff should be alert to AKI risk in individual patients that may lead to increased clinical monitoring or a change in treatment.
AKI in medico-legal cases
AKI is common and likely to occur in many medico-legal cases, although it may not be immediately obvious. Due to the ubiquitous nature of blood test investigations including kidney function checks, both in hospitalised patients and in the community, it is likely that a closer review of these investigations will identify kidney issues like AKI. This is important to flag up as the occurence of AKI can have immediate and long-term consequences for health and wellbeing. Think Kidneys (https://www.thinkkidneys.nhs.uk) is a national campaign raising awareness of the importance of kidneys for life and health, both AKI and chronic kidney disease. It is important for medico-legal teams to equally have greater awareness of kidneys in their wide variety of cases and seek expert consult where required.
References
• Improving global outcomes (KDIGO) acute kidney injury work group: KDIGO clinical practice guideline for acute kidney injury. Kidney Int Suppl. 2012;2(1):1–138
• Acute Kidney Injury (AKI) Algorithm; https://www.england.nhs.uk/akiprogramme/aki-algorithm/
• Wang HE, Muntner P, Chertow GM, Warnock DG. Acute kidney injury and mortality in hospitalized patients. Am J Nephrol. 2012;35(4):349–55
• Selby NM, Crowley L, Fluck RJ, McIntyre CW, Monaghan J, Lawson N, Kolhe NV. Use of electronic results reporting to diagnose and monitor AKI in hospitalized patients. Clin J Am Soc Nephrol. 2012;7(4):533–40
• Stewart J, Findlay G, Smith N, Kelly K, Mason M. Acute kidney injury: adding insult to injury. National Confidential Enquiry into Patient Outcome and Death. 2009.
• Recommended Minimum Requirements of a Care Bundle for Patients with AKI in Hospital; https://www.thinkkidneys.nhs.uk/aki/wp-content/uploads/sites/2/2015/12/AKI-care-bundle-requirements-FINAL-12.07.16.pdf
• Communities at Risk of Developing Acute Kidney Injury; https://www.thinkkidneys.nhs.uk/wp-content/uploads/2015/07/Communities-at-risk-of-developing-AKI-Think-Kidneys-010715.pdf
• Roberts G, Phillips D, McCarthy R, Bolusani H, Mizen P, Hassan M, Hooper R, Saddler K, Hu M, Lodhi S. Acute kidney injury risk assessment at the hospital front door: what is the best measure of risk? Clin Kidney J. 2015;8(6):673–80
• Acute kidney injury: prevention, detection and management (NICE Guidance CG169) - https://www.nice.org.uk/guidance/cg169
• Chronic kidney disease in adults: assessment and management (NICE Guidance CG182) - https://www.nice.org.uk/guidance/cg182
• KDIGO Clinical Practice Guidelines for Acute Kidney Injury - https://www.kdigo.org/clinical_practice_guidelines/pdf/KDIGO%20AKI%20Guideline.pdf
• Doyle, J.F., Forni, L.G. Acute kidney injury: short-term and long-term effects. Crit Care 2016; 20, 188