Chronic Kidney Failure Flashcards
Give examples of risk factors that could contribute to the development of CKD
Diabetes mellitus and hypertension are the two most common causes.
Vascular disease: Hypertension, renal artery atheroma, vasculitis.
Glomerular disease: Glomerulonephritis, diabetes, amyloid, SLE.
Tubulointerstitial disease: Pyelonephritis/interstitial nephritis, nephrocalcinosis, tuberculosis.
Obstruction and others: Myeloma, HIV nephropathy, scleroderma, gout, renal tumour, inborn errors of metabolism (e.g. Fabrys disease).
Congenital/inherited: Polycystic kidney disease, Alports syndrome, congenital hypoplasia.
Give an overview of the pathogenesis of chronic kidney disease.
After renal injury the kidneys will initially compensate by increasing filtration through remaining nephrons (=adaptive hyper filtration). Increased glomerular pressure contributes to progressive renal damage and glomerulosclerosis.
As renal failure progresses the kidneys lose ability to both excrete phosphate and produce 1,25-dihydroxycholecalciferol (active form of vit D).
Serum phosphate ⬆️ while calcium⬇️.
This stimulates increased parathormone causing 2° hyperthyroidism and eventually bone disease (renal osteodystrophy)
Anaemia develops because the kidneys stop producing erythropoietin which stimulates erythropoiesis.
Impaired excretion of potassium and hydrogen ions results in hyperkalaemia and metabolic acidosis.
Describe the epidemiology of chronic kidney disease.
Prevalence of CKD in general population is 5%.
The incidence of end stage renal failure caused by CKD has risen steadily particularly in those >65yrs.
Commonest causes are diabetes mellitus, glomerulonephritis, hypertension, and vascular disease.
What would a patient with CKD complain of in their history?
Anorexia, nausea, malaise, pruritus.
Later: diarrhoea, drowsiness, convulsions, coma.
Symptoms of the cause and other complications.
What would be found on examination of a patient with CKD?
Systemic: Kussmauls breathing (acidosis), signs of anaemia, oedema, pigmentation, scratch marks.
Hands: Leuconychia, brown line at distal end of nail. There may be an arteriovenous fistula (buzzing lump in wrist or forearm).
Signs of complications (e.g. neuropathy, renal bone disease).
What investigations would you perform if you suspected your patient had chronic kidney disease?
Blood: FBC (⬇️ Hb: normochromic, normocytic), U&E (⬇️ urea and creatinine), eGFR (can be derived from creatinine and age using the MDRD calculator), ⬇️Ca2+ , ⬆️ phosphate, AlkPhos, PTH.
Investigate for suspected aetiology: e.g. ANCA, ANA, glucose.
24-h urine collection: Protein, creatinine clearance (which is a rough estimate of GFR).
Imaging:
Signs of osteomalacia and hyperparathyroidism.
CXR may show pericardial effusion or pulmonary oedema.
Renal ultrasound: Measure size, exclude obstruction and visualize structure.
Renal biopsy: For changes specific to the underlying disease, contraindicated for small kidneys.
How would you manage a patient with CKD?
Treat the underlying cause: Control diabetes
Manage complications of chronic kidney disease:
•Anaemia: Correct iron stores. Regular IV or SC erythropoietin (usually monthly).
•BP control: ACE inhibitors and Angiotensin-II antagonists (caution with renal artery stenosis).
•Hypocalcaemia: Maintain serum levels with 1-hydroxylated vitamin D analogues, e.g. alfacalcidol. Consider bisphosphonates.
•Diet: High-energy intake, potassium intake restriction (in hyperkalaemia or acidosis, oral NaHCO3 may be required),
•restriction of protein and phosphate intake (using phosphate binders, e.g. calcium bicarbonate or aluminium hydroxide to ⬇️ phosphate absorption).
•Drugs: Avoid nephrotoxic drugs (e.g. NSAIDs). Dose adjustments for drugs excreted from kidneys.
•Oedema: Diuretics, e.g. furosemide (frusemide), metolazone.
Renal replacement therapy:
•Peritoneal dialysis (CAPD): Dialysate is introduced and exchanged through a Tenkoff catheter, inserted via a subcutaneous tunnel into the peritoneum.
•Haemodialysis: Blood is removed via an arteriovenous fistula surgically constructed in the wrist or forearm to provide high flow. Uraemic toxins are removed by diffusion across a semipermeable membrane in an extracorporeal circuit (this may activate coagulation so patients are heparinized).
•Renal transplantation: Requires long-term immunosuppressants to ⬇️ rejection (e.g. steroids, ciclosporin A, tacrolimus, azathioprine, daclizumab).
What complications are associated with CKD?
Haematological:
Anaemia (⬇️ erythropoietin production, ⬇️ marrow activity, ⬇️ RBC survival, ⬇️ dietary Fe/folate, ⬆️ blood loss: haemodialysis/sampling), abnormal platelet activity (bruising, epistaxis).
CVS: Accelerated atherosclerosis, ⬆️ BP, pericarditis.
Neuromuscular: Peripheral & autonomic neuropathy, myopathy.
Renal osteodystrophy: Osteoporosis, osteomalacia (⬇️ 1a-hydroxylation of vitamin D), secondary or tertiary hyperparathyroidism, adynamic bone disease (⬇️ bone turnover and fractures secondary to excessive suppression of the parathyroid gland with current therapies), osteosclerosis.
Endocrine: Amenorrhoea, erectile impotence, infertility.
Peritoneal dialysis: Peritonitis (e.g. staphylococcus epidermidis). Haemodialysis:
•Acute: Hypotension (excessive removal of extracellular fluid).
•Long-term:
—Atherosclerosis.
—Sepsis (secondary to peritonitis, Staph. aureus infection).
—Amyloidosis: Failure of removal of b2-microglobulin (component of HLA molecules) by dialysis membranes ➡️ periarticular deposition ➡️ arthralgia (e.g. shoulder) and carpal tunnel syndrome.
—Aluminum toxicity: Accumulation of aluminum from the dialysis fluid and phosphate binders ➡️ dementia, osteodystrophy, microcytic anaemia (rare).
Transplantation/immunosuppression: ⬆️ BP, opportunistic infections (e.g. CMV), malignancies (lymphomas and skin), recurrence of renal disease (e.g. Goodpastures syndrome), side-effects of drugs (e.g. steroids: features of iatrogenic Cushings syndrome; ciclosporin: gum hyperplasia).
What is the prognosis for a patient with CKD?
Depends on complications. Timely dialysis and transplantation ⬆️ survival.
Define chronic kidney failure
Chronic renal failure or chronic kidney disease (CKD) is defined as either kidney damage or GFR
