nephro

• Alport's syndrome is a genetic disorder characterized by glomerulonephritis, end-stage kidney disease, and hearing loss. It can also affect the eyes, leading to abnormalities such as lenticonus. However, it does not cause anosmia or loss of smell.
• Vomiting hydrochloric acid will create a metabolic alkalosis from hydrogen ion loss and hypochloraemia from loss of chloride. Hypokalaemia is a consequence of the process: dehydration and sodium loss stimulates the production of aldosterone via the renin-angiotensin-aldosterone system and therefore sodium is reabsorbed at the collecting duct in exchange for potassium, which is lost in the urine.
• In calculating the anion gap the formula below is often used;([Na+] + [K+]) - ([Cl] + [HCO3])The anion gap is used to classify metabolic acidosis into either;

  • Raised anion gap seen in e.g. diabetic ketoacidosis or,
  • Normal anion gap seen in patients with diarrhoea due to gastrointestinal bicarbonate loss.
• Alport's syndrome is usually inherited in an X-linked dominant pattern*. It is due to a defect in the gene which codes for type IV collagenresulting in an abnormal glomerular-basement membrane (GBM). The disease usually presents in childhood is more severe in males with females rarely developing renal failure.
• A normal anion gap is 8-14 mmol/L
• Causes of a normal anion gap or hyperchloraemic metabolic acidosis

  • gastrointestinal bicarbonate loss: diarrhoea, ureterosigmoidostomy, fistula
  • renal tubular acidosis
  • drugs: e.g. acetazolamide
  • ammonium chloride injection
  • Addison's disease
• Causes of a raised anion gap metabolic acidosis

  • lactate: shock, hypoxia
  • ketones: diabetic ketoacidosis, alcohol
  • urate: renal failure
  • acid poisoning: salicylates, methanol
  • 5-oxoproline: chronic paracetamol use
• AKI

  Prerenal

  • hypovolaemia secondary to diarrhoea/vomiting
  • renal artery stenosis

  Intrinsic

  • glomerulonephritis
  • acute tubular necrosis (ATN)
  • acute interstitial nephritis (AIN), respectively
  • rhabdomyolysis
  • tumour lysis syndrome

  Postrenal

  • kidney stone in ureter or bladder
  • benign prostatic hyperplasia
  • external compression of the ureter
• Spironolactone is an aldosterone antagonist which acts in the cortical collecting duct.Indications

  • ascites: patients with cirrhosis develop a secondary hyperaldosteronism. Relatively large doses such as 100 or 200mg are often used
  • hypertension: used in some patients as a NICE 'step 4' treatment
  • heart failure (see RALES study below)
  • nephrotic syndrome
  • Conn's syndrome

  Adverse effects

  • hyperkalaemia
  • gynaecomastia: less common with eplerenone
• Normal anion gap ( = hyperchloraemic metabolic acidosis)

  • gastrointestinal bicarbonate loss: 
  • prolonged diarrhoea: may also result in hypokalaemia
  • ureterosigmoidostomy
  • fistula
  • renal tubular acidosis
  • drugs: e.g. acetazolamide
  • ammonium chloride injection
  • Addison's disease

  Raised anion gap

  • lactate: 
  • shock
  • sepsis
  • hypoxia
  • ketones:
  • diabetic ketoacidosis
  • alcohol
  • urate: renal failure
  • acid poisoning: salicylates, methanol
• Henoch-Schonlein purpura (HSP), an IgA-mediated vasculitis that is characterised by abdominal pain, arthralgia and a purpuric rash over the buttocks and lower limbs. A preceding viral illness, including a viral upper respiratory tract infection, may be seen before the onset of HSP. There is an overlap between HSP and IgA-nephropathy so patients should have regular monitoring of their blood pressure and urinalysis to monitor for the onset or progression of renal disease for 6-12 months, even if the initial readings are normal.
• classic triad of nephritic syndrome (haematuria, oliguria, and hypertension)
• ECG changes are associated with hypocalcaemia:

  • Common: Corrected QT interval prolongation
  • Rare: Atrial fibrillation or torsade de pointes

  (Note: In hypercalcaemia shortening of the QT interval may be observed, in severe cases Osborn (or J-waves) may be present)
• While nonsteroidal anti-inflammatory drugs (NSAIDs) typically worsen renal function and are usually withheld in AKI, aspirin represents an exception when used for cardioprotective purposes e.g. angina. Aspirin's role as an antiplatelet agent involves the inhibition of platelet activation and aggregation, which underpins its continued use despite AKI.
• Haemolytic uraemic syndrome is generally seen in young children and produces a triad of:

  • acute kidney injury
  • microangiopathic haemolytic anaemia
  • thrombocytopenia
• A good mnemonic to remember the key drugs to stop in AKI is CANADA:C - Contrast media. A - ACE inhibitors. N - NSAIDs - apart from cardioprotective aspirinA - Aminoglycosides. D - Diuretics. A - Angiotensin receptor blockers (ARBs).