Chronic Kidney Disease
Macroscopic appearance of chronic kidney disease
Chronic kidney disease (CKD) is the clinical syndrome of the metabolic and systemic consequences of a gradual, substantial, and irreversible reduction in the excretory and homeostatic functions of the kidneys. Chronic kidney disease is defined as either kidney damage or a decreased kidney glomerular filtration rate (GFR) of <60 mL/min/1.73 m2 for 3 or more months. Most common cause could be chronic glomerulonephritis. With ever increasing number of diabetes mellitus, diabetic nephropathy leading to chronic kidney disease becoming common.
Stage ---- GFR (ml /min)--- Descriptor
1 --- > 90---- Kidney disease with normal or increased GFR.
2 ----60 - 89-- Kidney disease with mildly reduced GFR.
3 ----30 - 59 --Moderately severe renal failure.
4 ----15 - 29 --Severe renal failure.
5 ----< 15 ----End – stage renal failure.
Established renal failure (also called end-stage renal failure, ESRF) is the situation in which dialysis is required to sustain life of any reasonable quality. Patients with chronic kidney disease stage 3 or lower (GFR >30 mL/min) generally are asymptomatic. Uremic manifestations in patients with chronic kidney disease stage 5 are believed to be secondary to an accumulation of toxins, the identity of which is generally not known.
Common causes of chronic kidney disease
- Diabetes Mellitus
- Glomerulonephritis ( chronic )
- Pyelonephritis (chronic)
- Polycystic kidney disease
- Renovascular disease
- Renal tumours
- Renal Tuberculosis
Various factors affecting the progression of chronic renal failure
- Age of onset
- Male gender
- Genetic factors
- Cigarette smoking
symptoms of chronic kidney disease
Patients with CRF can present with modest or no symptoms, or as a uremic emergency. In about one-third of cases, the need for dialysis is imminent by the time the patient is seen in a renal unit.
- Nocturia and polyuria
- Nausea, vomiting & diarrhoea
- Bone pain
- Symptoms of carpel tunnel syndrome
Signs of chronic kidney disease
- Short stature
- Brown discoloration of nails
- Scratch marks
- Purpura / bruising
- Hypertension and complications
- Signs of fluid overload
- Pericardial friction rub
- Mixed peripheral neuropathy
- Carpel tunnel syndrome
- Proximal myopathy
Assessment of glomerular filtration rate
- Diagnose CKD
- Assess the severity of CKD
Assessment of GFR with Creatinine clearance (CC)
CC = U V / P
U = Urinary creatinine,
V = Urinary volume,
P = Plasma creatinine
Calculation of Creatinine clearance
Cockcroft - Gault formula
K x [140 – age (years)] x weight (kg)
Plasma creatinine (µmol/l)
K - Women - 0.85
Men - 1.23
Limitation of creatinine clearance to assess glomerular filtration rate
With progressive renal failure tubular excretion of creatinine is increased. This will lead to overestimate of glomerular filtration rate. Certain drugs like Cimetidine, Spironolactone inhibit tubular excretion of creatinine.
The most accurate estimation of glomerular filtration rate involves measurement of clearance of radiolabelled EDTA or Iohexol, a non ionic contrast medium.
- Haematuria may indicate glomerulonephritis, but other sources must be excluded.
- Proteinuria, if heavy, is strongly suggestive of glomerular disease. Urinary infection may also cause proteinuria.
- Glycosuria with normal blood glucose is common in CRF.
- White cells in the urine usually indicate active bacterial urinary infection, but this is an uncommon cause of renal failure; sterile pyuria suggests papillary necrosis or renal tuberculosis.
- Eosinophiluria is strongly suggestive of allergic tubulointerstitial nephritis or cholesterol embolization.
- Granular casts are formed from abnormal cells within the tubular lumen, and indicate active renal disease.
- Red-cell casts are highly suggestive of glomerulonephritis.
- Urine osmolality is a measure of concentrating ability.
- A low urine osmolality is normal in the presence of a high fluid intake but indicates renal disease when the kidney should be concentrating urine, such as in hypovolaemia or hypotension.
- Urine electrophoresis and immunofixation is necessary for the detection of light chains, which can be present without a detectable serum paraprotein.
- This should always be performed.
- Early-morning urine samples should be cultured if tuberculosis is possible.
- Urea - disproportionately high level seen in percatabolism and dehydration.
- Creatinine - elevated in all cases of CKD.
- Potassium - high level seen in severe CKD. Indicates potential cardiotoxicity and response to angiotensin converting enzyme inhibitors.
- Bicarbonate - reduced level in metabolic acidosis.
- Calcium - reduced in renal osteodystrophy.
- Phosphate - increased in renal osteodystrophy.
- Parathyroid hormone - increased in renal osteodystrophy.
- Hemoglobin is to assess the need for erythropoietin.
- Eosinophilia suggests vasculitis, allergic tubulointerstitial nephritis, or cholesterol embolism.
- Markedly raised viscosity or ESR suggests myeloma or vasculitis.
- Fragmented red cells and/or thombocytopenia suggest intravascular haemolysis due to accelerated hypertension, hemolytic uremic syndrome or thrombotic thrombocytopenic purpura.
- Complement components may be low in active renal disease due to SLE, mesangiocapillary glomerulonephritis, post-streptococcal glomerulonephritis, and cryoglobulinaemia.
- Autoantibody screening is useful in detection of scleroderma Wegener's granulomatosis and microscopic polyangiitis and Goodpasture's syndrome.
- Cryoglobulins should be sought in patients with unexplained glomerular disease, particularly mesangiocapillary glomerulonephritis.
- Antibodies to streptococcal antigens (ASOT, anti-DNase B) should be sought if post-streptococcal glomerulonephritis is possible.
- Antibodies to hepatitis B and C may point to polyarteritis or membranous nephropathy (hepatitis B) or to cryoglobulinaemic renal disease (hepatitis C).
- Antibodies to HIV raise the possibility of HIV-associated renal disease.
- Electrophoresis and immunofixation should be performed for myeloma.
- Ultrasound - every patient should undergo ultrasonography (for renal size and to exclude hydronephrosis).
- Plain abdominal radiography and CT (without contrast) to exclude low-density renal stones or nephrocalcinosis, which may be missed on ultrasound.
- CT is also useful for the diagnosis of retroperitoneal fibrosis and some other causes of urinary obstruction, and may also demonstrate cortical scarring.
- MRI Magnetic resonance angiography in renovascular disease.
- This should be performed in every patient with unexplained renal failure and normal sized kidneys, unless there are strong contraindications.