AkI Flashcards
Location of kidneys
T12 to L3
Lie in retroperitoneum of the abdomen
which kidney is lower
R
What is the renal corpuscle made of
Glomerulus (ball of capillaries) enclosed by the bowman’s capsule
Where does the glomerulus receive blood from and where does it drain
Afferent arteriole and is drained by efferent arteriole
What is GFR influenced by
COntractile tone of the arterioles
What do the renal tubules consist of
PCT
Loop of Henle
DCT
Collecting duct
Role of PCT
Reabsorb Na+
Regulate pH by secreting bicarbonate
Which part of LoH is impermeable to ions
descending limb
Which part of LOH is v permeable to water
Descending limb
What is the ascending limb permeable and impermeable to
Ascending- permeable to ions (Na+/K+ and Cl-)
Impermeable to water
How does the ascending limb reabsorb ions
Thin part- passive diffusion
Thick part- active transport
Role of Distal convoluted tubule
regulation of K+ sodium Ca+ and pH
Macula densa- involved paracrine function of kidney via RAAS. they do this by detecting NaCl and adjust GFR and renin excretion
Role of collection duct
Electrolye and fluid balance
Affected by ADH and Aldosterone
Function of kidney
Electrolyte balance Regulation of BP Calcium homeostasis Acid base homeostasis Nitrogenous waste excretion Drug excretion Red cell production (by secreting EPO) Fluid balance
RAAS system
1) Low bP
2) Renin turns angiotensin into angiotensin 1
3) ACE turns it into angiotensin 2
4) Causes vasoconstriction of arterioles which increases BP
5) OR causes adrenal cortex to release aldosterone which increases Na+ and water reabsorption in kidneys and increases secretion of K+ and H+ into urine. This increases blood volume and BP
What is AKI
rapid decline in kidney function. Measured by serum urea and creatinine
Results in failure to maintain fluid, electrolyte and acid-base homeostasis
Risk factors for AKI
>65yo Hypovolaemia Sepsis Diabetes Chronic liver disease cardiac failure CKD
What is a pre-renal cause of AKI
Reduced renal perfusion (blood flow) leads to a reduction in GFR
What is intrinsic renal cause of AKI
Injury or damage to renal parenchyma
What is post renal cause of AKI
Obstruction of the urinary tract to any point from the calyx to urethra
Examples of prerenal causes of AKI
Hypovolaemia (haemorrhage, dehydration, third space losses, increased urinary output, burns, GI losses)
Hypotension (distributive shock)
Fluid overload (cardiac failure, cirrhosis, nephrotic syndrome)
Reduced cardiac output (cariogenic shock, arrhythmias myocardial infarction, congestive HF)
Vascular (renal artery stenosis/occlusion, Drug induced e.g. NSAIDs, ACEI, Renal vein thrombosis, AAA
Examples of intrinsic causes of AKI
Glomerular (gmolerulonephritis, thrombosis, haemolytic uraemic syndrome, IgA nephropathy)
acute interstitial nephritis (Drugs e.g. NSAIDs, autoimmune nephritis, lymphoma)
Acute tubular necrosis (prolonged ischaemia, nephrotoxins e.g. ahminoglycosides, light chains in myeloma), rhabdomyolysis, radio contrast agents
Vascular (vasculitis, thrombosis/emboli from angiography)
Examples of post renal causes of AKI
Luminal- stones, clots, sloughed papillae
Mural- malignancy, BPH, strictures
Extrinsic compression- pelvic malignancy, retroperitoneal fibrosis
Symptoms of AKI
Reduced urinary output N&V Dehydration COnfusion fatigue
How to categorise patients with AKI
Serum creatinine and urine output
Diagnosis of AKI
Serum creatinine >26 micromol/L in 48h
50% or more rise in serum creatinine to have occurred within 7 days
fall in urinary output <0.5mL/kg/hour for more than 6 consecutive hours
Bedside tests
Urine dip and culture
OBS
ECG
Bloods
U&E, FBC, LFT, clotting, CRP
ABG for acid-base imbalance
Immunology if indicated
Creatinine kinase if indicated
Imaging
Renal US to rule out obstruction
CXR if pulmonary oedema
CT KUB if obstruction
Complications of AKI
Hyperkalaemia Volume overload Uraemia CkD Metabolic acidosis Electrolyte imbalances (hyperphosphatemia, hyponatraemia, hypermagnesaemia, hypocalcaemia)
Causes of flank pain
Renal colic Pyelonephritis AAA perforated peptic ulcer Biliary pathology BOwel obstruction Lower lobe pneumonia MSK
Ureteric obstruction causes
Stones, clots, severe constipation
Enlarged prostate, strictures, malignancy, pregnancy, congenital abnormalities
Ureteric obstruction signs and symptoms
Pain, N&V, frank haematuria, difficulty passing urine, recurrent UTIs
Frequency, oliguria, haematuria, hypertension, pyrexia, rigours
Risk factors for kidney stones
Males 30-50yo Anatomical abnormalities HTN Gout Hyperparathyroidism Immobilisation Dehydration Met disorders
3 sites of constriction in ureter
Pelviureteric junction (renal pelvis–> ureter)
Pelvic brim (where iliac vessels transverse the ureter at midureter point)
Vesicoureteric junction (ureter–> posterior aspect of bladder)
