Renal Disease
Anatomy
Kidneys = paired organs; L 11-14cm x W5-6cm x D3-4cm; each weighs 150g.
Lie retroperitoneally, either side of vertebral column at level of T12 - L3. Right kidney lies 1.5cm lower than left (due to
liver). Move with respiration - downwards (3cm) with inspiration and upwards with expiration.
Renal parenchyma: outer cortex and inner medulla
Nephron - functional unit of the kidney; nephron = glomerulus + proximal tubule + loop of Henle + distal tubule +
collecting duct
Renal capsule and ureters innervated by T10-12 and L1 nerve roots.
Blood supply: renal arteries - branches of abdominal aorta. Multiple renal artery branches within the kidney: interlobar
arteries, arcuate arteries, interlobular arteries. Afferent glomerular arterioles arise from the interlobular arteries,
supplying the glomerular capillary bed, which drains via the efferent glomerular arterioles. These in turn drain into the
peritubular capillary network, which drain into the renal vein. Blood from the juxtamedullary glomeruli passes via the
vasa recta in the medulla. Venous blood ultimately drains into inferior vena cava. Left renal vein longer (therefore used
more commonly for live donor transplant nephrectomy).
Physiology
Renal Function
Excretory Elimination of waste products + drugs; final urine volume - 1-2L/day.
Urine concentration - countercurrent mecahnism
Regulation Regulation of body fluid volume + composition
Filtration and Free ultrafiltration of water and non-protein-bound low-MW compounds from plasma
Reabsorption 25% Cardiac output (1300mL/min) passes through the 2million glomeruli.
60-80% filtered water and sodium reabsorbed in the proximal tubule with essentially all K+, bicarbonate,
glucose and amino acids
Further water and sodium chloride reabsorbed more distally; fine tuning of NaCl and water balance in
distal and collecting tubules - regulated by ADH and aldosterone.
Calcium, phosphate and magnesium selectively reabsorbed - maintains electrolyte composition
Potassium: freely filtered at glomerulus; completely absorbed in proximal tubule and excreted in distal
tubules and collecting ducts.
Acid base-balance: filtered bicarbonate largely reabsorbed; H+ ions excreted (mainly buffered by
phosphate)
Endocrine renin-angiotensin system; production of EPO, renin, prostaglandins, endothelia's
Metabolic Metabolism of vitamin D and small molecular weight proteins
Glomerular Filtration Rate
Healthy individuals: GFR remains relatively constant - infrarenal regulatory mechanism.
Disease: GFR falls when reduced intrarenal blood flow/ damage to or loss of glomeruli/ obstruction along renal tubule;
this results in reduced ability to eliminate waste products and inability to regulate body fluid volume and composition.
This results clinically as: increased blood urea, increased plasma creatinine, reduced GFR.
GFR measurement: inulin clearance/ creatinine clearance.
Tubular Function and Tests
Tubular function: selective reabsorption/ excretion of water and electrolytes
Proximal tubular tests (x5): Hypokalaemia (PT failure of K+ reabsorption; thiazide diuretics; hyperaldosteronism);
Hypophosphataemia (PT abnormality; gut phosphorous binders; primary hyperparathyroidism); glycosuria in the
absence of hyperglycaemia; generalised aminoaciduria; proteins derived from tubular cells (B2-microglobulin)
Distal tubular tests (x2): measure urinary concentrating capacity in response to water deprivation, measure urinary
acidification.
RENAL DISEASE - 1
Anatomy
Kidneys = paired organs; L 11-14cm x W5-6cm x D3-4cm; each weighs 150g.
Lie retroperitoneally, either side of vertebral column at level of T12 - L3. Right kidney lies 1.5cm lower than left (due to
liver). Move with respiration - downwards (3cm) with inspiration and upwards with expiration.
Renal parenchyma: outer cortex and inner medulla
Nephron - functional unit of the kidney; nephron = glomerulus + proximal tubule + loop of Henle + distal tubule +
collecting duct
Renal capsule and ureters innervated by T10-12 and L1 nerve roots.
Blood supply: renal arteries - branches of abdominal aorta. Multiple renal artery branches within the kidney: interlobar
arteries, arcuate arteries, interlobular arteries. Afferent glomerular arterioles arise from the interlobular arteries,
supplying the glomerular capillary bed, which drains via the efferent glomerular arterioles. These in turn drain into the
peritubular capillary network, which drain into the renal vein. Blood from the juxtamedullary glomeruli passes via the
vasa recta in the medulla. Venous blood ultimately drains into inferior vena cava. Left renal vein longer (therefore used
more commonly for live donor transplant nephrectomy).
Physiology
Renal Function
Excretory Elimination of waste products + drugs; final urine volume - 1-2L/day.
Urine concentration - countercurrent mecahnism
Regulation Regulation of body fluid volume + composition
Filtration and Free ultrafiltration of water and non-protein-bound low-MW compounds from plasma
Reabsorption 25% Cardiac output (1300mL/min) passes through the 2million glomeruli.
60-80% filtered water and sodium reabsorbed in the proximal tubule with essentially all K+, bicarbonate,
glucose and amino acids
Further water and sodium chloride reabsorbed more distally; fine tuning of NaCl and water balance in
distal and collecting tubules - regulated by ADH and aldosterone.
Calcium, phosphate and magnesium selectively reabsorbed - maintains electrolyte composition
Potassium: freely filtered at glomerulus; completely absorbed in proximal tubule and excreted in distal
tubules and collecting ducts.
Acid base-balance: filtered bicarbonate largely reabsorbed; H+ ions excreted (mainly buffered by
phosphate)
Endocrine renin-angiotensin system; production of EPO, renin, prostaglandins, endothelia's
Metabolic Metabolism of vitamin D and small molecular weight proteins
Glomerular Filtration Rate
Healthy individuals: GFR remains relatively constant - infrarenal regulatory mechanism.
Disease: GFR falls when reduced intrarenal blood flow/ damage to or loss of glomeruli/ obstruction along renal tubule;
this results in reduced ability to eliminate waste products and inability to regulate body fluid volume and composition.
This results clinically as: increased blood urea, increased plasma creatinine, reduced GFR.
GFR measurement: inulin clearance/ creatinine clearance.
Tubular Function and Tests
Tubular function: selective reabsorption/ excretion of water and electrolytes
Proximal tubular tests (x5): Hypokalaemia (PT failure of K+ reabsorption; thiazide diuretics; hyperaldosteronism);
Hypophosphataemia (PT abnormality; gut phosphorous binders; primary hyperparathyroidism); glycosuria in the
absence of hyperglycaemia; generalised aminoaciduria; proteins derived from tubular cells (B2-microglobulin)
Distal tubular tests (x2): measure urinary concentrating capacity in response to water deprivation, measure urinary
acidification.
RENAL DISEASE - 1
