Renal disease Flashcards
What are the major functions of the kidney?
Glomerular function
- Excretion of toxic end-products of metabolism
Tubular function
- Water, Acid-base and electrolyte balance
Endocrine function
1 Alpha Hydroxylase -> Vitamin D metabolism
Erythropoetin -> Haemoglobin synthesis
Renin -> Renin-Angiotensin-Aldosterone Axis
Prostaglandins and endothelins
Gluconeogenesis - the renal cortex contains glucose-6-phosphatase
Describe the functional unit of the kidney
Glomerulus
- Ultrafiltration
Proximal Convoluted Tubule:
- Reabsorption of water, glucose, amino acids, K+, HCO3, Na+
Loop of Henle:
- Concentration of ultrafiltrate
Distal Convoluted Tubule:
- Secretion of urate
Na+ -K+ via aldosterone; Na+ -K+/H+ exchange
Collecting duct:
- Water reabsorption under ADH control
What is the functional unit of the kidney?
The nephron
What is renal failure?
A failure of the kidneys to function adequately
Acute (ARF) that occurs in hours/days, and is life threatening and is usually reversible
Chronic (CRF) occurring over months/years and usually leads to End Stage Renal Failure (ESRF)
What are the causes of acute renal failure?
Sudden impairment of blood flow
Toxin build up:
- drugs
- bacterial
What are the causes of chronic renal failure?
Diabetes
Sustained Hypertension
Long term drug use
What is the purpose of the biochemistry investigations of renal failure?
Primarily try to assess glomerular filtration and the integrity of the nephron
Assess tubular function: tests tend to be associated with specific conditions often involving hormonal control
Measure circulating non-protein nitrogenous compounds
Urine concentrating ability
List the renal function tests
glomerular filtration rate=GFR plasma creatinine
urine creatinine plasma urea
urine volume urine urea
cystatin C in plasma? urine protein
urine albumin urine phosphate
amino acids urine glucose
haematuria osmolality
What is glomerular filtrate?
An ultrafiltrate of plasma i.e plasma without most of the large proteins
What does glomerular function depend on?
- Adequate renal blood flow and pressure
* Number of functioning nephrons
What is normal glomerular filtration rate?
120 mL/min. = 170 L/day
How is glomerular filtration rate determined?
In the laboratory by the ‘creatinine clearance’ test
