RENAL DISEASE

ACUTE KIDNEY INJURY

Acute kidney injury (AKI)  is a clinical syndrome characterised by a decline in renal excretory function over hours or days that can result in failure to maintain, fluid, electrolyte and acid-base balance. The term has replaced the concept of acute renal failure because it more accurately describes the state of the kidneys before function fails.

AKI arises as a result of decreased glomerular filtration rate; structural damage to the kidney; acute obstruction of urinary flow.

Pre-renal causes include hypovolaemia, reduced cardiac output and drugs that reduce blood pressure, circulating volume or renal blood flow, e.g. ACE inhibitors, ARBs, NSAIDs, loop diuretics. Post-renal causes include obstruction such as renal stones, blocked catheter, enlarged prostate or genitourinary malignancy.

Management depends on the stage of AKI and if there are features requiring hospital admission, same-day referral or specialist input.

Renal function should be monitored regularly in people with chronic kidney disease, heart failure, liver disease, and diabetes. Review regular medication, and where possible, avoid potentially nephrotoxic drugs, and adjusting the dose of other medication according to renal function.    

CHRONIC KIDNEY DISEASE

CKD is a long-term condition in which waste products normally removed by the kidneys remain in the blood. A person with CKD is at increased risk of heart attack or stroke, especially if they smoke or are overweight. CKD affects about 1 in 10 of the UK population, and at age ≥75 years 1 in 2 because of normal ageing of kidneys. Fewer than 1 in 10 people with CKD ever require dialysis or a kidney transplant, but people with CKD should have regular checks of kidney function and blood pressure. In the UK, CKD is most often caused by diabetes (CKD is a common complication of diabetes), uncontrolled or poorly treated hypertension, or an age-related decline in kidney function. There are other less common causes. The focus of primary care management is cardiovascular risk reduction. Control of blood pressure, especially in individuals with proteinuria, reduces cardiovascular risk and slows progression of kidney disease, delaying the need for dialysis or transplantation.

 

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Identifying and monitoring CKD

Declining kidney function is identified and quantified by 'estimated glomerular filtration rate' (eGFR). Monitoring is by a combination of: a) eGFR b) urine albumin:creatinine ratio (ACR), to detect proteinuria.

Screening for CKD NICE recommends screening for CKD (using eGFR and ACR) in people at risk because of:

• diabetes
• hypertension
• cardiovascular disease (ischaemic heart disease, chronic heart failure, peripheral vascular disease, cerebral vascular disease)
• structural renal tract disease, renal calculi, prostatic hypertrophy
• multisystem disease with potential kidney involvement, e.g. systemic lupus erythematosus (SLE)
• family history of hereditary stage 5 CKD.

CKD prevalence increases with age, and it is more common in females and some ethnic groups, but do not screen for CKD on the basis of age, sex or ethnicity alone. eGFR reporting has identified many people with CKD, most of whom are asymptomatic. Only a few will progress to end-stage renal disease, but all are at increased risk of CVD. Practical tips on measuring kidney function (NICE NG203)

• Interpret eGFR with caution in individuals with extreme muscle mass.
• Confirm an eGFR result of
• A rise in serum creatinine of >20% or a fall in eGFR of >15% should trigger further measurements within 2 weeks.
• Check serum creatinine and potassium levels before starting angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs). Repeat within 2 weeks of starting, or increasing dose.
• Process samples within 12 h of venepuncture. Avoid delays in dispatching samples to the laboratory.
• Advise people not to eat meat for at least 12 h before a blood test for eGFR. Use of fasting samples is at the discretion of local renal units (check your local guidelines).

Practical tips for measuring proteinuria

• Do not use reagent strips to identify proteinuria unless they can specifically measure albumin at low concentrations and express the result as an albumin:creatinine ratio (ACR).
• Use ACR, not protein:creatinine ratio (PCR) to detect and identify proteinuria (more sensitive at low levels).
• PCR is an alternative to ACR for quantification and monitoring of proteinuria, but use ACR for people with diabetes.

CKD review Every patient with CKD should be reviewed at least annually, depending on their condition, with recent blood results, urine test and BP reading, to:

• assess condition, monitor symptoms and disease progression.
• assess presence of depression.
• review results or findings.
• review medication: check that drugs are prescribed as per guidelines, or document contraindications or side-effects preventing use; assess effectiveness of additions or alterations; check adherence with medication; re-issue prescription as appropriate.
• discuss/monitor lifestyle issues - diet, smoking, alcohol consumption, exercise, and BMI.
• offer seasonal vaccination/s.
• offer management plan if indicated.
• discuss concerns or worries; in males, consider erectile dysfunction resulting from condition or medication.

Be aware of QOF indicators, and ensure correct application of Read codes.