Serve me up a slice of KIDNEY pie - Renal Failure

A good dose of Steak and  Renal Pie

My third post is an overview of the subject I am asked most frequently to teach, renal medicine.  Students find this one of the most difficult areas of medicine to get their heads around, probably because to understand the pathology and how to investigate/treat it you really need to understand the complex physiology of the kidneys.

The most useful starting point is revising what the kidneys do and where they do it:

Bowmans Capsule/Glomerulus

 

Filtration/Retention - 

BP control  Produce humoral agents  (Juxtaglomerular apparatus/interstitium)

        Erythropoietin 

        Active metabolites of vitamin D    

        Renin   

Tubules  

Na+/H20 homeostasis
K+ Homeostasis
•H+ Homeostasis
Secretion of toxins  

Once this is clear in your head you can work out what will stop working and the complications of this.  

Glomerular disease will cause problems  due to filtration/retention failure with loss of normal blood products:

Protein - Oedema

WBC/Complement - Infection

Anticoagulant Factors -Thrombosis

Tubular disease will cause most of the dangerous complications of renal failure all of which are indications for dialysis

Na+/H20 homeostasis - Pulmonary oedema

K+ Homeostasis - Hyperkalaemia

•H+ Homeostasis- Metabolic Acidosis

Secretion of toxins - Uraemic Syndrome

The easy way to tell the difference between the causes clinically is to check the urine for protein.  Which will be present in large amounts in Glomerular disease

Looking at the functions again can tell you the complications of Chronic Kidney Disease - Anaemia, HTN Hypocalcaemia, Renal oestrodystrophy.

Acute Kidney Injury is defined as the rapid fall in glomerular filtration rate (GFR) The biochemical surrogate for this is the acute rise in Creatinine.  It can be split broadly into 3 categories: 

• Pre-renal
• –Blood supply 
• •Renal
• –Glomerulonephritis
• –Acute tubular necrosis 
• Toxic or Ischaemic
• –Interstitial nephritis
• Infection or Drug Allergy 
• •Post-renal
• –Ureteric obstruction 
• –Urethral obstruction 

In the PRESENTATION you can find more in depth coverage of Nephrotic syndrome (non proliferative) renal cause and the infective (proliferative) renal causes, the old word for which is nephritic.  The glomerulonephritis also get delved into in a good bit more depth.  

Stuff to look up for next time, the causes, physiology and treatment of the three main types of glomerulonephritis that come up in exams:

•Minimal change glomerulonephritis

•Focal segmental glomerulosclerosis

•Membranous glomerulonephritis