Clinical Nephrology Flashcards Preview

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Flashcards in Clinical Nephrology Deck (30):

What is the endocrine role of the Kidney?

Produces erythropoietin in response to hypoxia and performs the hydroxylation of 1-(OH)D3 (hydroxycholecalciferol) to produce calcitriol


What happens after Kidney failure?

Loss of excretory functions (toxins)

Loss of homeostatic function (electrolytes, acid-base, volume state)

Loss of endocrine (erythropoietin production and VitD hydroxylation)

Abnormality of glucose homeostasis


What can happen to electrolyte levels during Kidney failure?

Hyponatraemia (leading to volume depletion) if problem with tubules, hypernatraemia if difficulty excreting sodium

Hyperkalaemia if excreting sodium (risk of arrhythmias - pointed T-waves)


How can renal failure cause lethargy?

Likely to have high plasma urea and creatinine (toxic so cause lethargy)


What are the endocrinological consequences of Renal failure?

Anaemia results due to reduced erythropoietin synthesis

Lower 1,25-(OH)2VitD3 and increased PTH because phosphate retention and low levels of calcitriol lead to hyperparathyroidism


What are the implications of Renal failure for the CV system?

Risk of MI increased (CKD greater predictor than smoking)


What happens to Salt and water levels during renal failure?

Renal dysfunction can lead to difficulty in salt and water excretion, causing hypertension, oedema and pulmonary oedema; osmotic diuresis occurs due to urea and inability to decrease sodium excretion when depleted leads to hypotension 


How does renal failure cause acidosis?

Decreased proton excretion and base retention; buffered by protons entering cells in exchange for potassium ions (increases hyperkalaemia); Kussmahl's respiration (air hunger), breathing rapidly and deeply to attempt to compensate for metabolic acidosis 


What are the risks of abnormal Potassium levels for the heart?

Hypokalaemia: risk of VF (sigmoid T-waves)

Hyperkalaemia: risk of asystole (pointed T waves, QRS broadening and loss of P waves)


What are the signs of Loss of Kidney function?

Anaemia, acidosis, hyperkalaemia, hyponatraemia tendency, oedema and hypertension


What are five tests for measuring GFR?

Creatinine clearance
Inulin Clearance
Radionuclide studies


Why is Urea not used to test GFR?

Poor indicator and confounded by diet, GI bleeding, drugs and liver function


What are the advantages and disadvantages of Creatinine testing?

Rapid and cheap

Affected by muscle mass (higher), age, race, sex (higher in men), diet


What are the disadvantages of a creatinine clearance test?

Difficult for elderly patients and overestimates low GFR


What are the advantages and disadvantages of Inulin clearance testing?

Laboratory gold standard

Laborious and not used in practice


What are the advantages and disadvantages of Radionuclide studies?

E.g. EDTA clearance - reliable
Expensive tho


What is eGFR?

Estimated GFR - uses equations to calculate GFR from serum creatinine and patient factors such as age, ethnicity and sex; unreliable when GFR > 60ml/min 


What is the general method of action of Diuretics?

Reduce sodium reuptake to retain water within the urine


Give an example of a loop diuretic and how it works:

e.g. Furosemide block the Na/K/Cl transporter of the ascending loop of Henle, leading to reduced movement of sodium into the lining and hence retention of electrolytes and water in the urine - most potent (can affect up to 25% load) 


What are Thiazides?

Block the Na+/Cl- transporter in the DCT, reducing sodium uptake, but also meaning that the Na+/Ca2+ exchanger on the basolateral surface becomes more active so more calcium is reabsorbed - (can affect 5-10% load)


What are osmotic diuretics?

Glucose/mannitol act as solutes to reduce the osmotic gradient and decrease water reabsorption (act on PCT/dLoH)


What are carbonic anhydrase inhibitors?

Inhibits carbonic anhydrase to reduce sodium reabsorption because fewer protons are available for the Na+/H+-ATPase pump


What are K+ Sparing diuretics?

Amiloride blocks sodium channels and spironolactone is an aldosterone antagonist (inhibits sodium channel and Na+/K+-ATPase) - small effect (can affect 3-5% load)


What do urine dipsticks test for?

Blood: indicates kidney/GU tract damage

Urobilinogen: liver disease

Bilirubin: biliary obstruction or liver disease

Protein: usually negative - protein indicates renal disease

Nitrite: produced by bacteria - indicate infection

Ketones: not usually present - can indicate disruption to carbohydrate metabolism

Glucose: should not normally be present - could indicate diabetes

pH: usually 5-9

Leukocytes: may indicate infection


What is renal replacement therapy?

Advanced CKD may necessitate haemo(dialysis) and/or transplant to replace the function of the kidneys


When is dialysis usually first started?

Usually started at GFR = 10ml/min or when indicated e.g. uraemia, severe hyperkalaemia, and uncontrolled acid-base disturbances


What is Haemodialysis?

Pumping blood via artificial kidneys where blood surrounded by electrolyte fluid to control solute, waste and water concentration of blood returned to body; can be done several times a week or daily, and at hospital or at home; risks of hypotension, infection and inflammation


What is peritoneal dialysis?

Dialysate fluid pumped into peritoneal cavity, with peritoneal capillaries acting as blood source; ultrafiltration controlled by altering osmolality of the dialysate; allows a more independent life; risk of back pain, infection, catheter problems and peritonitis 


What is renal transplantation, including where it is placed, and when it is contraindicated:

Provides best long term outcomes, and may come from living/cadaveric donors; new kidney placed extraperitoneally in the iliac fossa; requires immunosuppression so contraindicated in AIDS, infection and cancer 


What dietary modifications should be given in renal failure?

Avoidance of high salt food as sodium will not be removed
Low potassium foods
Consideration of phosphate intake (not usually a problem in early CKD)
Do not restrict protein
Fluid restriction in advanced CKD
VitD supplementation
Iron tablets if anaemic