B/ 68 End stage kidney and renal failure

Question 1

Functions of the kidney

Answer 1

Excretion of waste products from the metabolism
Regulation of body salt and water balance
Maintenance of appropriate acid balance
Secretion of hormones and autacoids (local factors which behave as hormones)

Question 2

Components of the kidney

Answer 2

Glomeruli, tubules, interstitium, blood vessels

Question 3

General information about kidney disease and damage to components

Answer 3

Some disorders affect more than one structure. Damage to one of the components of the kidney can lead to secondary damage to another components or multiple other components.
Chronic disease eventually leads to damage to all the components of the kidney. This is what culminates into chronic kindey failure and what is called end stage kidney.

Question 4

Two important terms regarding kidney damage

Answer 4

Azotemia and Uremia

Question 5

Azotemia

Answer 5

A biochemical abnormality associated with renal failure. Characterized by blood urea nitrogen (BUN) being above 9mmol/L, and creatinin being above 120micromol/L.
Largely related to a decreased GFR. Azotemia can be divided into two forms: pre-renal azotemia and post-renal azotemia.

Question 6

Pre-renal azotemia

Answer 6

Hypoperfusion of the kidney (such as in the case of shock) leads to a decreased GFR.

Question 7

Post-renal azotemia

Answer 7

Due to obstruction of urine outflow below the level of the kidney.

Question 8

Uremia

Answer 8

When azotemia progresses to include clinical manifestations and systemic biochemical abnormalities. Thus Uremia = azotemia + Clinical manifestations + biochemical abnormalities.

Question 9

Clinical manifestations of uremia

Answer 9

Fluid electrolyte disturbances
Calcium and phosphate disturbances
Cardiac alterations
Pulmonary alterations
Haematopoietic alterations
GI alterations
Skin alterations
Neuromuscular alterations

Question 10

Fluid electrolyte disturbances

Answer 10

Tubular disease leads to polyuria. Polyuria can lead to dehydration and a high electrolyte level.
Glomerular problems can lead to decreased filtration which leads to salt and water retention. This can lead to edema, cardiac failure due to increased blood volume and hyperaldosteronism (which further increases the salt and water retention). Patients with kidney failure usually have metabolic acidosis because they have a decreased ability to remove waste products.

Question 11

Calcium and phosphate disturbances

Answer 11

The kidney normally excretes phosphate. When the kidney is damaged, the concentration of phosphate increases. When phosphate increases, it binds calcium and decreases the concentration of calcium, which stimulates release of PTH. This all sums into renal osteodystrophy and hypermetastatitc calcifications.

Question 12

Cardiac alterations

Answer 12

Uremia has toxic effects on the vessels which leads to increased permeability of the vessels - allowing for fibrinogen to leak out into the pericardium. This form the fibrous “bread and butter” pericarditis.
Left ventricular hypertrophy and cardiac failure occurs.

Question 13

Pulmonary alterations

Answer 13

Pleuritis and hyaline membrane like disease as a consequence of the toxic effects (uremic pneumonitis).

Question 14

Haematopoietic alterations

Answer 14

Anemia, because the synthesis of EPO is decreased. Increased bleeding tendency due to decreased production of tissue factor.

Question 15

GI alterations

Answer 15

Gastroenteritis generated by the toxins.

Question 16

Skin alterations

Answer 16

Itching of the skin, yellowish skin color due to the precipitation of products in different organs.

Question 17

Neuromuscular abnormalities

Answer 17

Peripheral neuropathy.

Question 18

Cause of the symptoms

Answer 18

It is not BUN in itself which causes the symtoms, but rather end products of nucleic acid breakdown (called middle weight proteins) and PTH (when continuously high it leads to cell damage).

Question 19

Acute renal failure

Answer 19

Dominated by oliguria and anuria (little and no urine flow). It can result from glomerular, interstitial, or vascular injury for example from acute tubular necrosis.

Question 20

Chronic renal failure

Answer 20

Characterized by prolonged symptoms of uremia. The end result of all chronic renal diseases.

Question 21

End stage kidney

Answer 21

Complete or almost complete failure of the kidney to function.

Question 22

End stage kidney disease (ESRD)

Answer 22

Usually occurs at the point when a chronic kidney disease has worsened to a stage where the kidneys only have a 10% functionality. Patients who have reached this stage require transplant or dialysis. The most common causes are diabetes and hypertension.

Question 23

Morphology of end stage kidney disease

Answer 23

Kidneys are symmetrical and shrunken. Surface is red-brown and diffusely granular. Glomeruli are mostly obliterated, thus the diffusion barrier is lost which leads to leakage and trapping of proteins. This leads to compression of adjacent structures and eventually sclerosis.
There is interstitial fibrosis due to atrophy of tubules and of the peritubular capillary network. Lymphocytic infiltration of the interstitium.
At this stage of the disease it is difficult to determine which component(s) was the origin of the disease.