Chronic Kidney Disease

» Nephrology

Overview

Overview CKD is responsible for a substantial burden of illness and premature death. The kidneys are basically not working as good.

Remember Always assume a ↓ eGFR represents acute kidney injury until proven otherwise

Definition
Acute Kidney Injury: Rapid reduction in kidney function over hours to days, as measured by serum urea and creatinine and leading to a failure to maintain fluid, electrolyte and acid-base homeostasis.
Acute Kidney Failure:
Chronic Kidney Disease: Impaired renal function >3months based on abnormal structure or function, or GFR <60 for >3months with evidence of kidney dysfunction

Kidney Physiology eGFR

More to come...

Limitations to eGFR

Accurate to +/- 30%

Not for use in children, pregnancy, dialysis

Extremes of body composition and size

Vegetarian diets

Rapidly changing renal function

Interferences with creatinine assays

Think If eGFR is < 60 mL/min/1.73 m2, consider clinical situations where eGFR results may be unreliable and/or misleading and retest within 14 days

GFR (mL/min) = GFR (mL/min/1.73m²) x BSA / 1.73

Risk Factors

Remember Proteinuria, which is a clinical marker for CKD, is also indicative of an increased risk of cardiovascular disease

Signs and Symptoms

Patients with CKD are often asymptomatic until the advanced stages

Fatigue (Anaemia)
Breathlessness (fluid overload/acidosis)
Pruritis (itching)
Restless legs
Bone pain
Leg swelling

Severe Chronic Kidney Disease (GFR <20mL/min)

Pericarditis
Serositis
Encephalopathy
Gastrointestinal bleeding
Uraemic neuropathy

Examination

Pallor
Lemon tinge skin (Uremia)
Scratch marks from pruritis
Pericardial rub (Uraemic complication)
Pleural effusions
Palpable kidneys (Polycystic Kidney Disease or hydronephrosis)
Peripheral Oedema

Differential Diagnosis

Common causes of Chronic Kidney Disease

Diabetes mellitus (Diabetic nephropathy)
Glomerulosclerosis
Reflux nephropathy
Obstructive nephropathy
Hypertension
Polycystic Kidney disease

Investigations

Determining Renal Function

GFR - creatinine clearance and plasma creatinine/urea level
Tubular function - glucosuria, EUC, CMP, plasma albumin
Urine analysis
CT scan - for renal artery stenosis or Urinary tract obstruction

Determine renal structure

Ultrasound - small kidneys suggest chronic disease
CT scan
Cystoscopy

Assess effects of Chronic Kidney Disease on body

FBC
Serum ferritin and iron
CMP
LFT
parathyroid hormone level
Nerve conduction studies
Arterial Doppler studies

Aetiology

Aetiology

Diabetic Nephropathy

Overview Type II diabetes Mellitus is the leading cause of Chronic Kidney Disease. It is classified as a secondary nephrotic syndrome. 20% of people with Type II diabetes will develop end stage kidney disease. Everyone with Diabetes should be screened yearly for microalbuminuria.

Clinical features - Nephrotic Syndrome with signs and symptoms of diabetes (hyperglycemia)

Pathological features Diabetic kidney disease is defined by characteristic structural and functional changes. The predominant structural changes include

Mesengial expansion
Glomerular basement membrane thickening
Glomerular sclerosis

Staging
Class I	Isolated glomerular basement membrane thickening. There is no evidence of mesangial expansion, increased mesangial matrix, or global glomerulosclerosis involving >50 percent of glomeruli.
Class II	Mild (class IIa) or severe (class IIb) mesangial expansion.
Class III	At least one Kimmelstiel-Wilson lesion (nodular intercapillary glomerulosclerosis) is observed on biopsy and there is <50 percent global glomerulosclerosis.
Class IV	Advanced diabetic sclerosis. There is >50 percent global glomerulosclerosis.

Pathogenesis

Management and Prognosis Microalbuminuria is reversible if caught early and managed vigorously.

Tight glycemic control
Right BP control with ACE/ARBs
Manage CV risk factors

More info on Long-Term Complications of Diabetes Type II

Pathophysiology

Video: Chronic Kidney Disease Pathophysiology

Staging

Staging according to GFR and albuminuria allows for a more complete description of risk for the major adverse outcomes of CKD

Stage	eGFR ml/min/1.73m²
Stage 1	>90 (Normal)
Stage 2	60-90 (Mild)
Stage 3a	45-60 (Moderate)
Stage 3b	30-44 (Moderate)
Stage 4	15-29 (Severe)
Stage 5	<16 (End-Stage)

The majority of patients with CKD stages 1–3 do not progress to kidney failure. The risk of death from CV disease is far higher than the risk of progression. Mild to moderate CKD is usually managed in general practice or by other physicians caring for the patient. Referral to nephrologist should be considered if:

Proteinuria with haematuria
Stage 4-5 CKD
Suspected rare cause of CKD
Poorly controlled BP
Rapidly falling eGFR

Remember Normal GFR is >90mL/min/1.73m² (130L/day)

Think Low eGFR and raised urine albumin are markers for death, CVD, End-Stage Kidney disease, Acute Kidney Injury

Management

General and limit progression/complication of CKD

Exclude Acute Kidney injury
Education
Stop Smoking
Weight reduction
Encourage exercise
Avoid alcohol
Vaccination
Fluid intake and diet
- Fluid and salt restriction are often important to prevent volume overload.
- A low-protein diet has been shown to slow the progression of renal failure in patients with CKD
- Phosphate restriction
- Potassium restriction
Cardiovascular risk reduction
- Hypertension - ACE inhibitors or ARBs
- Hypercholesterolaemia - Statins
- Aspirin prophylaxis if not contraindicated

Think CKD with hyperkalaemia be careful with using ACE inhibitors or K+ sparing diuretics.

Symptomatic treatment (usually associated with uraemia)

Anorexia
Taste disturbance
Dyspepsia
Constipation
Dyspnoea
Dry skin and pruritus
Anxiety and Depression
Confusion
Restless legs

Treat complications

Anaemia
- Erythopoesis stimulating agents
- Oral/intravenous iron
Acidosis
Phosphate/calcium/bones
- Hyperphosphataemia - Dietary restriction, phosphate binders (aluminium hydroxide)
- Vitamin D
- Hypocalcaemia - calcimimetics
- Secondart/Tertiary hyperparathyroidism - Parathyroidectomy