What Happens When The Kidneys Stop Working What Happens When The Kidneys Stop Working Loss of excretory function – accumulation of waste products Loss of homeostatic function – disturbance of electrolyte balance, loss of acid-base control, inability to control volume homeostasis Loss of endocrine function Clinical features are determined by rate of deterioration What Causes The Symptoms Of Lethargy And Anorexia Patients with renal failure present with lethargy and anorexia Accumulation of nitrogenous waste products, hormones, peptides Acidosis Hyponatraemia Volume depletion (low BP) Anaemia Salt And Water Imbalance In Patients With Renal Problems Salt and water loss usually found in patients with tubulointerstitial disorders in which concentrating mechanisms damaged More usual for patients with renal dysfunction to have difficult excreting salt and water leading to sodium retension (resulting in hypertension, oedema and pulmonary oedema) Salt and water imbalance caused by – inability to decrease sodium excretion, osmotic diuresis due to high conc. of waste substances in urine High loss of salt and water results in volume depletion causing low blood pressure Implications Of Acidosis Caused by decreased excretion of H+ ions and retention of acid bases Buffered by H+ ions passing into cells in exchange for K+ ions (aggravating tendency to hyperkalaemia) Compensation mechanism – increasing CO2 loss through lungs – air hunger Exacerbates anorexia and increases muscle catabolism Implications Of Hyperkalaemia Caused by failure of distal tubule to secrete potassium Exacerbated by acidosis Can cause cardiac arrhythmias and arrest Clinical features of hyperkalaemia dependent on chronicity of hyperkalaemia Kidney As A Metabolic Organ Decreased erythropoietin production in renal failure results in anaemia Low 1-25 Vit. D levels result in poor intestinal calcium absorption, hypocalcaemia (short term) and hyperparathyroidism (longer term) Increased cardiovascular risk
Major predictor of end stage kidney disease is chronic kidney disease Major outcome for patient with chronic kidney disease is cardiovascular disease Acute Loss Of Kidney Function Anaemia Acidosis Tendency to hyperkalaemia Hypocalacemia Renal size unchanged Acute metabolic complications Tendency to hyponatraemia Volume usually overloaded – oedema, hyptertension Previously normal creatinine Chronic Loss Of Kidney Function Anaemia Acidosis Tendency to hyperkalaemia Renal osteodystrophy Renal size often reduced Chronic uraemic symptoms Tendency to hyponatraemia Volume usually overloaded – oedema, hypertension Previously abnormal creatinine Initial Management Of Patient Patient has renal failure – lethargy and anorexia, hypotension, hyperkalaemia, hyponatraemia, metabolic acidosis Intravenous normal saline to correct fluid depletion Intravenous sodium bicarbonate to correct acidosis Intravenous insulin and dextrose to lower plasma potassium (by driving K + back into cells) Transfer to hospital for dialysis Assessing GFR Urea – poor indicator, confounded by diet, catabolic state, GI bleeding, drugs, liver function Creatinine – affected by muscle mass, age, race, sex, need to look at patient when interpreting result Creatinine clearance – difficult for elderly patients to collect accurate sample Estimated GFR – equation which automatically calculates GFR from serum creatinine, easiest equation uses age and ethnicity, alternatives can include weight, albumin, generally unreliable once GFR >60 ml/min Inulin clearance – laborious, used for research purposes only Radionuclide studies – EDTA clearance, reliable but expensive Stages Of CKD Stage 1 – normal GFR (>90 ml/min/1.73m2), with other evidence of chronic kidney damage
Stage 2 – mild impairment, GFR 60-89 ml/min/1.73m2, with other evidence of chronic kidney damage Stage 3 – moderate impairment, GFR 30-59 ml/min/1.73m2 Stage 4 – severe impairment, GFR 15-29 ml/min/1.73m2 Stage 5 – established renal failure, GFR <15 ml/min/1.73m 2 or on dialysis Long Term Management Remains on regular haemodialysis for 4hrs 3 times/week Low potassium diet and fluid restriction Erythropoietin injections to correct anaemia 1.25 vitamin D supplements to prevent hyperparathyroid bone disease