8. What happens when the kidneys stop working? Flashcards
(24 cards)
What 4 things happen when the kidneys stop working?
Loss of excretory function (accumulation of waste)
Loss of homeostatic function (electrolyte balance, acid-base control, volume)
Loss of endocrine function (erythropoietin, 1-alpha-hydroxylase Vit D)
Abnormality of glucose homeostasis (Decreased gluconeogenesis)
What causes the symptoms of lethargy and anorexia?
Accumulation of nitrogenous waste products Acidosis Hyponatremia Volume depletion Anaemia
What could cause salt and water imbalance? (“Salt retentainers”)
Inability to excrete salt and water, leads to a tendency to retain Na+ (Causes Hypertension, Oedema and Pulmonary oedema)
What could cause salt and water imbalance? (“Salt losers”)
Tubulointerstitial disorders in which the conc. mechanisms have been damaged
Inability to decrease Na+ excretion (i.e. increase Na+ reabsorption) when Na+ depleted.
Causes osmotic diuresis (as high conc. small MW waste substances, e.g., urea)
What does an inappropriately high loss of salt result in?
Volume depletion
Low BP
Signs and symptoms of renal failure
“Very unwell” Pale, Hands cold Capillary refill decreased Poor skin turgor Low pulse rate Low BP Tachypnoeic Clear lungs on auscultation
What in a blood test may indicate renal failure?
High plasma creatinine and urea
Ultrasound findings in renal failure
Small, shrunken kidneys
What is acidosis caused by?
Decreased excretion of H+ ions and retention of acid bases
Why does acidosis tend to aggravate hyperkalaemia?
Excess H+ is buffered by taking it into cells in exchange for K+
So extracellular K+ concentration increases
How can serum and total body sodium levels vary?
Can have low Na+ in blood, but excess total body Na+ if oedematous
Can have high Na+ in blood, but low total body Na+
Conc. not always aligned to total body levels
What respiratory compensation mechanism is seen in response to metabolic acidosis?
Increasing CO2 loss through the lungs
Air hunger, rapid breathing
What is a serious consequence of hyperkalaemia?
Can cause CARDIAC ARRHYTHMIAS
initial loss of p waves, bradycardia, arrest
What can hyperkalaemia effect?
Neural and muscular activity
What effect does renal failure have on the production of erythropoietin? What is the result of this?
Decreases erythropoietin production
Results in anaemia
What effect does renal failure have on 1-25 Vitamin D levels? What is the result of this?
Decreases levels of 1-25 Vitamin D
Results in hypocalcaemia (short term) and hyperparathyroidism (long term)
A major predictor of end stage renal failure is chronic kidney disease, but what is a major outcome for patients with chronic kidney disease?
Cardiovascular Disease
What potential mechanisms cause CVD in patients with CKD?
Hypertension
Secondary cardia effects
Endothelial effects
Lipid abnormalities
State 5 similarities between acute and chronic kidney disease.
Anaemia Acidosis Tendency to hyperkalaemia Tendency to hyponatreamia Volume usually overloaded (Oedema)
State 2 differences between acute and chronic kidney disease.
Acute: renal size unchanged + previously normal creatinine
Chronic = renal size DECREASED, previously ABNORMAL creatinine, chronic uraemia symptoms
When might a patient with chronic kidney disease have normal sized kidneys?
Polycystic kidney disease
Diabetes
Myeloma
Amyloid
What is the initial management plan for someone suffering from kidney disease?
IV saline to correct fluid loss
IV sodium bicarbonate to correct acidosis
IV insulin and dextrose to lower plasma K+ (increase uptake of K+ into cells)
What are the methods of estimating GFR?
Urea (poor indicator: confounded by diet, drugs, liver function) Creatinine (affected by muscle mass, age, race, sex) Creatinine Clearance (difficult in elderly patients to collect an accurate sample) Inulin Clearance (laborious) Radionuclide Studies (EDTA clearance, expensive)
Estimated GFR (EGFR) equation
Equation accounts for creatinine, age and ethnicity
Still need to look at patient
