Interpreting U and Es Flashcards
What are the causes of increased urea?
Caused by increased protein breakdown so dehydration, GI bleeding, trauma, infection, malignancy, high protein intake
What investigations do all patients with AKI require?
Urine dipstick
Bloods - FBC, U and E, CRP, Calcium, Phosphate, PTH
VBG - look for low bicarb/metabolic acidosis and hyperkalaemia
Accurate fluid balance chart
Stopping renally excreeted and nephrotoxic drugs
What are the causes of pre-renal AKI?
Hypovolaemia/sepsis (most common cause), renovascular disease, cardiorenal failure (increased venous pressure reduces renal perfusion pressure)
What are the main investigations and treatment for pre-renal AKI?
Investigate with fluid assessment and renal artery doppler
Treat cause e.g. IV fluids in hypotension
What are the causes of intrinsic renal failure?
acute tubular necrosis (ischaemic or nephrotoxic)
Acute interstitial nephritis
Acute glomerulnephitis
What are the main investigations for intrinsic renal failure?
Urine dipstick for blood and protein in glomerulonephritis
Urine protein/creatinine ratio (<15mg/mmol = normal, >300mg/mmol = nephrotic)
Nephritic screen: ANA, ANCA, Anti-GBM, hepatitis
Myeloma - protein electrophoresis and serum free light chains
Creatine kinase if rhabdo suspected
Renal biopsy - if nephritic screen positive or glomerulonephritis suspected
What is the treatment for intrinsic renal failure?
Treat the cause
Stop causative agents for acute interstitial nephritis
Steroids, diuretics and ace inhibitor may be required for glomerulonephritis
What are the causes of post renal failure?
Ureters - stones, stricture, compression
Bladder - neurogenic, bladder calculi, tumour
Urethra - BPH, prostate cancer, stricture
What are the investigations for post renal failure?
Renal tract USS
Bladder scan
What is the treatment for post renal failure?
Relieve obstruction - catheter if urethral, nephrostomy if ureteric
What are the indications for dialysis in AKI?
AEIOU Acidosis Electrolyte abnormalities (Hyperkalaemia) Intoxicants - methanol etc Overload Ureamia - Urea >60 or encephalopathy
What are the common causes of chronic kidney disease?
Diabetes (secondary to glomerular disease)
Chronic hypertension
Chronic glomerulonephritis
Polycycstic kidney disease
What is the management of CKD?
General measures - fluid restriction, dietary protein restriction, ACE inhibitor Treat complications: -hypertension - antihypertensives -Anaemia - ESA + iron supplements -Oedema - fluid restriction -Secondary hyperparathyroidism: --Kidney unable to reabsorb calcium so causes hyperparathyroidism -- GIve active vit D therapy --Dietry phosphate restriction --If calcium low then give supplement tablets -Acidosis - give sodium bicarb -hyperlipidaemia - give statin -Hyperkalaemia - potassium restriction
How does aldosterone effect electrolyte levels?
It causes increased sodium reabsorption and increased pottasium excretion in the distal convoluted tubule
What are the symptoms of hyponatraemia?
Nausea/vomiting
headache
seizures
reduced consciousness
What are the causes of hyponatraemia?
Hypovalaemic - Na+ lost and water follows:
-Urinary sodium >30 - Diuretics, addisons disease (increased K+), kidney injury
-Urinary sodium <30 Na + lost from elsewhere- Dirrhoea/vomiting
Euvolaemic - H2O gained:
-Urinary Na+ >30 - SIADH, Hypothyroidism
-Urinary Na+ <30 - H2O intoxication
Oedematous - retention of water that is disproportionate to the retention of sodium - congestive cardiac failure, hypoalbuminaemia
What investigations should be done for hyponatraemia?
Plasma osmolality to confirm if true hyponatraemia:
-Low=true
-Normal =False (pseudohyponatraemia due to high lipids
-High = dilutional (due to high glucose)
Urine sodium concentration
Specific tests to confirm causes e.g. synacthen for addisons, TFTs for hypothyroidism
What is the management of hyponatraemia?
Treat cause
Correct sodium
-seizures consider 3% hypertonic saline with ICU input
-Hypovolaemia - replace lost fluid with 0.9% saline - slowly if chronic e.g. 1L over 12 hours
-Euvolaemic - correct cause
-If SIADH or oedematous then fluid restrict to 1L/day
What are the symptoms of hypernatraemia?
Thirst
Confusion
Muscle spasms
What are the causes of hypernatraemia?
Euvolaemic - iatrogenic e.g. too much IV sodium containing fluids
Hypovolaemic:
-Small volumes of concentrated urine - dehydration
-Normal urine - diabetes insipidus, osmotic diuresis e.g. DKA
What are the investigations for hypernatraemia?
Urine and serum osmolality
Fluid deprivation test to confirm diabetes indipidus
What is the management of hypernatraemia?
Treat ause
Sodium correction:
-Most patients - 5% dextrose, slowly if chronic
-Signs of volume depletion - replace lost fluid with 0.9% saline
How do insulin and catecholamine increase K+ cellular uptake?
They cause stimulation of the ATPase Na+/K+ pump
What are the symptoms of hypokalaemia?
Arrhythmias
Tremour
Muscle weakness/cramps
Constipation