Chronic Kidney Disease

• Chronic kidney disease ( CKD ) describes a chronic reduction in kidney function sustained over three months.
• CKD is often permanent and progressive.
• Kidney function naturally declines with age.
• Factors that can speed up the decline and cause CKD include: Diabetes, Hypertension, Medications (e.g., NSAIDs or lithium), Glomerulonephritis, Polycystic kidney disease.
• Most patients with CKD are asymptomatic.
• Signs and symptoms as the renal function worsens may be non-specific: Fatigue, Pallor (due to anaemia), Foamy urine (proteinuria), Nausea, Loss of appetite, Pruritus (itching), Oedema.
• The estimated glomerular filtration rate ( eGFR ) is based on the serum creatinine, age and gender.
• The eGFR estimates the glomerular filtration rate (the rate at which fluid is filtered from the blood into Bowman’s capsule).
• Proteinuria (protein in the urine) is quantified with a urine albumin:creatinine ratio ( ACR ).
• Haematuria (blood in the urine) can be assessed with a urine dipstick or microscopy.
• The Kidney Failure Risk Equation can be used to estimate the 5-year risk of kidney failure requiring dialysis.
• Renal ultrasound helps identify obstructions (e.g., kidney stones or tumours) and polycystic kidney disease.
• Treating the underlying cause involves optimising diabetic control, optimising hypertension control, reducing or avoiding nephrotoxic drugs (where appropriate), and treating glomerulonephritis (where this is the cause).
• The G score is based on the eGFR.
• A diagnosis can be made when there are consistent results over three months of either: Estimated glomerular filtration rate (eGFR) sustained below 60 mL/min/1.73 m2 or Urine albumin:creatinine ratio (ACR) sustained above 3 mg/mmol.
• Macroscopic haematuria refers to visible blood in the urine.
• Complications of CKD include Anaemia, Renal bone disease, Cardiovascular disease, Peripheral neuropathy, End-stage kidney disease, Dialysis-related complications.
• NICE clinical knowledge summaries (May 2023) suggest referral to a renal specialist when: eGFR less than 30 mL/min/1.73 m2, Urine ACR more than 70 mg/mmol, or 5-year risk of requiring dialysis over 5%.
• The A score is based on the albumin:creatinine ratio.
• Microscopic haematuria is when blood is identified on testing but not visible on inspection.
• The blood pressure target is less than 130/80 in patients under 80 with CKD and an ACR above 70 mg/mmol.
• Other investigations are necessary to identify risk factors, including: Blood pressure (for hypertension), HbA1c (for diabetes), Lipid profile (for hypercholesterolaemia).
• Haematuria can indicate infection, malignancy (e.g., bladder cancer), glomerulonephritis or kidney stones.
• Accelerated progression is a sustained decline in the eGFR within one year of either 25% or 15 mL/min/1.73 m2.
• G Stage eGFR A Stage Albumin:Creatinine Ratio G1 Over 90 A1 Under 3 mg/mmol G2 60-89 A2 3-30 mg/mmol G3a 45-59 A3 Above 30 mg/mmol G3b 30-44 G4 15-29 G5 Under 15
• Reduced phosphate excretion by diseased kidneys results in high serum phosphate.
• Dapagliflozin is the SGLT-2 inhibitor licensed for CKD and is offered to patients with diabetes plus a urine ACR above 30 mg/mmol, considered for patients with diabetes plus a urine ACR or 3-30 mg/mmol, and non-diabetics with an ACR of 22.6 mg/mmol or above.
• Chronic kidney disease leads to less vitamin D activity and low serum calcium.
• Healthy kidneys metabolise vitamin D into its active form, which is essential in calcium absorption in the intestines and reabsorption in the kidneys.
• Iron deficiency is treated before using erythropoietin, and intravenous iron is usually given, particularly in dialysis patients.
• Osteomalacia occurs due to increased turnover of bones without adequate calcium supply.
• Anaemia in Chronic Kidney Disease is treated with erythropoiesis-stimulating agents, such as recombinant human erythropoietin, and blood transfusions can sensitise the immune system, increasing the risk of future transplant rejection.
• Exercise, maintaining a healthy weight and avoiding smoking are ways to reduce the risk of complications in CKD.
• Renal bone disease, also known as chronic kidney disease-mineral and bone disorder (CKD-MBD), involves high serum phosphate, low vitamin D activity, low serum calcium, and reduced phosphate excretion.
• Parathyroid hormone stimulates osteoclast activity, increasing calcium absorption from bone.
• Medications that help slow the disease progression in Chronic Kidney Disease (CKD) include ACE inhibitors and SGLT-2 inhibitors.
• Management of complications in CKD involves oral sodium bicarbonate to treat metabolic acidosis, iron and erythropoietin to treat anaemia, vitamin D, low phosphate diet and phosphate binders to treat renal bone disease, and dialysis or renal transplant for end-stage renal disease.
• Atorvastatin 20mg is recommended for primary prevention of cardiovascular disease in all patients with CKD.
• ACE inhibitors are offered to all patients with diabetes plus a urine ACR above 3 mg/mmol, hypertension plus a urine ACR above 30 mg/mmol, and all patients with a urine ACR above 70 mg/mmol.
• The parathyroid glands react to the low serum calcium and high serum phosphate by excreting more parathyroid hormone, causing secondary hyperparathyroidism.