Module 10: Excretory System Disorders

urinary tract obstruction

• can occur at any site along the urinary tract

• obstruction impedes flow

• causes:

  • kidney stone

  • compression from a tumour

  • inflammation

  • congenital

obstructive uropathy

• anatomical changes in the urinary system caused by obstruction

hydronephrosis

• progressive dilation of the renal collecting ducts and tubules

• glomerular filtration continues, so pressure builds up, first in the renal pelvis and then in tubules

hydroureter

caused by obstruction within ureter

stasis of urine

• increases possibility of infection and stone formation

kidney stones

• most common cause of upper urinary tract infection

  • kidneys, ureters, and urinary bladder

• also known as urinary calculi

• age, fluid intake, diet

• crystals, proteins or other substances

• most common stones are composed of calcium oxalate or phosphate

• small stones have 50% chance of spontaneous passage, where larger stones have almost no chance of spontaneous passage

renal colic

• clinical manifestation of kidney stone

• excruciating pain in the flank and abdomen caused by a 1-5 mm stone moving into the ureter and stretching it

neurogenic bladder

• cause of lower urinary tract obstruction

• bladder dysfunction caused by neurologic disorders (CNS or peripheral nerve damage)

physical obstruction

• cause of lower urinary tract obstruction

• scarring of the urethra( infection, surgery), enlarged prostate

glomerulonephritis

• inflammation of glomerulus

• causes: hypertension, immunologic responses, infection, diabetes mellitus

• 2nd leading cause of kidney failure

nephritic syndrome

• manifestation of glomerular disease

• sudden excretion of blood cells, protein, diminished GFR, oliguria

• caused by: inflammation that blocks the glomerular capillary lumen and damages the capillary wall (typically associated with post infectious glomerulonephritis)

nephrotic syndrome

• manifestation of glomerular disease

• nephrosis

• massive proteinuria and lipidura

• edema (hallmark manifestation)

• group of manifestations resulting from loss of protein that includes thrombotic complications, increased risk of infection, etc

• caused by:

  • increase in glomerular permeability due to blood vessel damage from eg. diabetes mellitus, SLE

BUN

• blood urea nitrogen

• concentration of urea in blood

• shows degree of :

  • glomerular filtration, urine concentrating capacity

acute kidney injury (AKI)

• sudden (less than two days) decline in kidney function

  • decrease in glomerular filtration

  • accumulation of nitrogenous waste products in the blood (BUN and plasma creatinine)

• potentially reversible, if can correct the cause before the permanent kidney damage has occurred

• ranges from minimal changes in renal function to complete renal failure requiring renal replacement therapy:

  • spectrum is described by RIFLE criteria

RIFLE

• based on glomerular filtration rate and urine output

• Risk

• Injury

• Failure

• Loss

• End stage disease

pre-renal acute kidney injury

• cause of AKI (acute kidney injury)

• decrease in GFR is caused by renal hypo perfusion

• if pressure continues to be low, lack of oxygen delivery can cause cell injury and necrosis\

• high BUN:creatinine ratio

  • due to low filtration and slow flow in tubules, which allows more reabsorption of urea

post renal acute kidney injury

• cause of AKI

• urinary tract obstructive disorder

• occurs with urinary tract obstruction that affects both kidneys

• causes an increase in pressure upstream, resulting in decreased GFR

• normal BUN:creatinine ratio

  • kidney words fine initially; problem is after the kidney makes urine

intrarenal acute kidney injury

• usually results from tubular necrosis as a result of occurrences including:

  • ischemia associated with pre renal failure

  • sepsis

  • nephrotoxic effects of drugs

• lower BUN:creatinine ratio

  • due to poor reabsorption of urea in the tubules

treatment of AKI

• maintain life until renal function has been recovered

  1. correct fluid and electrolyte balance

  2. treat infections

  3. maintain nutrition

• continuous renal replacement therapy or hemodialysis may be required

chronic kidney disease

• defined by kidney damage or a GFR <60 ml/min for 3 months of longer (normal >=90ml/min)

• 5 stages

• risk factors:

  • hypertension, diabetes mellitus, chronic glomerulonephritis, obstructive uropathies

intact nephron hypothesis

• unaffected nephrons are capable of hypertrophy and hyper function

• puts stress on healthy nephrons, which hastens their failure

compensation

• what is done to maintain the pH in response to disturbances

partially compensated

• one of the systems is attempting to rectify the disturbance, but has not yet been successful, resulting in values for that system that are outside normal ranges

fully compensated

• pH levels are within normal limits, but values for both systems are outside of normal limits (in opposite directions)

corrected state

• all values are within normal limits

hypernatremia

• retention or therapeutic infusion of sodium

  • retention cam be caused by over secretion of aldosterone or ACTH

  • IV infusion - sodium bicarbonate to treat acidosis

• increased loss of fluids

  • sweating, watery diarrhea, excessive urination

• decreased water intake

hyponatremia

• decreased concentration of sodium ions in the blood

• water moves into the cells (osmosis), causing cells to swell

hyperkalemia

• excess potassium ions in the blood

• caused by:

  • renal disease

  • under secretion of aldosterone

  • increased intake

  • a shift from intracellular to extracellular: changed cell permeability caused by trauma, hypoxia, acidosis

  • insulin deficits

hypokalemia

• derceased concentration of potassium ions in the blood

• due to

  • excessive loss of potassium

  • inadequate intake

  • increased entry into cells

hypocalcemia

• due to decreased PTH, kidney disease, alkalosis

• leads to increased excitability of both muscles and nerves

• Trosseau’s sign and Chvostek’s sign

Magnesium

• cofactor in many intracellular enzymatic reactions

• nerve conduction

• smooth muscle contraction and relaxation

hypermagnesemia

• decreased excitability of both muscles and nerves

• hypoactive reflexes

• muscle weakness

• brachycardia, respiratory distress

• nausea, vomiting

hypomagnesemia

• increased excitability of both muscles and nerves

• increased reflexes

• muscle cramps and convulsions

• tachycardia

• behavioural changes, irritability

azotemia

• increased levels of serum urea and other nitrogenous compounds

uremic syndrome

• the systemic signs and symptoms associated with the accumulation of nitrogenous wastes and toxins in the plasma brought about through kidney failure.

anasarca

• general accumulation of fluid in body cavities and tissues

cardiovascular system

• effect on body system

• major cause od death in CKD (chronic kidney disease)

• excess sodium leads to hypertension

• excess LDL leads to increased atherosclerosis

pulmonary system

• effect on body system

• complications associated with fluid overload

• acidosis results in kussmal respirations

hematologic system

• effect on body system

• anemia (erythropoietin is produced by the kidneys), impaired platelet function (possibly due to uremia)

immune system

• effect on body system

• overall suppression by high levels of urea and metabolic eastes

neurologic system

• effect on body system

• numerous effects of uremic toxins, including both peripheral and central nervous system

  • restless leg syndrome, muscle atrophy, headache, impaired concentration 0 with later stages, seizures, coma

gastrointestinal system

• effects on body system

• anorexia, vomiting, possibly due to breakdown of urea by intestinal bacteria

endocrine and reproductive systems

• effects on body system

• decrease in levels of sex steroids bring symptoms, such as impotence and amenorrhea

• insulin resistance and alterations in thyroid hormone metabolism can occur