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DISORDERS OF RENAL FUNCTION

Terms in this set (48)

The kidneys play an important role in the regulation of fluids and electrolytes, and when they malfunction it often leads to an electrolyte imbalance. Electrolytes are charged particles involved in the transmission of impulses in nerve and muscles. When imbalances occur, this can lead to serious complications and even death.
Potassium
The kidney is the primary organ responsible for potassium excretion. When potassium builds up in the bloodstream, it is called hyperkalemia. Hyperkalemia can cause abdominal cramping, tiredness, muscle weakness or paralysis.
Sodium
Sodium plays a major role in fluid balance, neuromuscular function and acid-base balance. The kidneys either conserve or excrete sodium depending on the body's needs. If the kidneys are not able to excrete sodium, hypernatremia will occur. Hypernatremia can lead to disorientation, muscle twitching, increased blood pressure and weakness.
Magnesium
An excess of magnesium affects the central nervous system, muscles and cardiac system: blood pressure drops, heart rate slows down, and in severe cases coma and cardiac arrest can occur.
Phosphorus and Calcium
Phosphorus and calcium levels are affected by renal failure. Because of the reciprocal relationship between phosphorus and calcium, the retention of phosphorus in renal failure causes a decrease in the level of calcium. Low levels of calcium cause muscle spasms, seizures and abnormal heart rhythms. The presence of high serum levels of phosphorus for extended periods of time may lead to additional complications. As calcium levels remain low, skeletal demineralization starts to occur and calcium deposits occur in vascular cells causing hardened arterial walls. This, in turn, can lead to enlargement of the left ventricle of the heart, high blood pressure and ultimately cardiac failure.
Renal size and volume decrease with age, accompanied by intrarenal vascular changes. The number of glomeruli decreases and the mass of the juxtamedullary nephrons falls. The result is a decrease in the filtration area of the glomerular basement membrane and decreased permeability. The glomerular filtration rate (GFR) is reduced with aging. The GFR is approximated by the endogenous creatinine clearance, which falls in parallel with the inulin clearance (the true measure of GFR) and is always greater because of tubular excretion of creatinine. Analytical methods for serum and urine creatinine overestimate its concentration and suffer, to varying degrees, from interferences, making the normal range method dependent. A further uncertainty arises from the use of a correction to standard surface area. Serum creatinine concentration is an insensitive indicator of renal function in the elderly. Deduction of creatinine clearance from serum creatinine concentration, weight and age using one of many formulae gives only approximate values, usually too high, and is unsuitable for debilitated and seriously ill patients. Tubular function, in general, is decreased in the elderly. The ability of the kidney to concentrate urine maximally after water deprivation decreases with age, as does the ability to excrete a water and salt load, particularly during the night. Nocturnal polyuria is common in the elderly. The aged kidney can maintain acid-base balance under normal conditions, but not when subjected to an acid load.
Stress Incontinence
Stress incontinence may happen when there is an increase in abdominal pressure -- such as when you exercise, laugh, sneeze, or cough. Urine leaks due to weakened pelvic floor muscles and tissues.

Causes of stress incontinence include pregnancy and childbirth, which cause stretching and weakening of the pelvic floor muscles. Other factors may also increase the risk for stress incontinence, such as being overweight, obesity, prostate surgery, and certain medications.

Urge Incontinence
Urge incontinence is often referred to as overactive bladder: You have an urgent need to go to the bathroom and may not get there in time, leaking urine.

Causes of overactive bladder include: Damage to the bladder's nerves; Damage to the nervous system; Damage to muscles

Conditions such as multiple sclerosis, Parkinson's disease, diabetes, and stroke can affect nerves, leading to urge incontinence. Other conditions such as bladder infections, bladder stones, and use of certain medications can also contribute to symptoms.

Overflow Incontinence
You may have overflow incontinence if you are not able to empty your bladder appropriately. As a result, you may have leakage once the bladder is already full. This is more common in men with symptoms of frequent dribbling of urine.

Causes of overflow incontinence include: Weak bladder muscles; Blockage of the urethra, such as by prostate enlargement; Medical conditions such as tumors causing obstruction of urine flow; Constipation

Functional Incontinence
With functional incontinence, physical problems such as arthritis, or cognitive problems such as dementia prevent you from getting to the bathroom in time.